SSHServer Component

Properties   Methods   Events   Config Settings   Errors  

The SSHServer component is used to create Secure Shell (SSH) servers. The component handles multiple simultaneous connections on the same Transmission Control Protocol (TCP)/IP port (service port). It is designed to balance the load between connections for a fast, powerful server.

Syntax

nsoftware.IPWorksSSH.SSHServer

Remarks

The SSHServer component is the Secure Shell (SSH)-enabled equivalent of the IPWorks TCPServer component, extended by a set of new properties and events that deal with SSH security. The SSHCompressionAlgorithms and SSHEncryptionAlgorithms properties determine which protocols are enabled for the SSH handshake. The SSHCert property is used to select a certificate for the server (note that a valid certificate must be selected before the server can function). The SSHUserAuthRequest event will allow you to use authenticate clients using digital certificates or passwords. Finally, the SSHStatus event provides information about the SSH handshake and underlying protocol notifications.

By default, each instance of SSHServer can handle up to 1000 simultaneous incoming connections (this number may be increased up to 100,000, or decreased to a lower value by using the MaxConnections configuration setting).

SSH connections are identified by a ConnectionId. Events relating to these connections as a whole will use the ConnectionId to identify the specific connection. Connections may also contain one or more multiplexed channels, which are identified by a ChannelId. Channel-level events will specify the ChannelId to which they relate.

SSHServer can start to listen on a port by setting the Listening property to True. When a remote host asks for a connection, the ConnectionRequest event is fired. At that point, the connection can either be accepted or rejected. If the connection is accepted, a ConnectionId is assigned, and communication can start. From this point on, the operation is similar to SSHClient. Data can be sent to an individual SSHChannel using SendChannelData. The address and port of the incoming connection can be found by querying the RemoteHost and RemotePort properties.

Threading in Server Applications

In .NET, all socket-based components perform all Socket.IO through asynchronous methods. Each call consumes a thread from the system's thread pool, and thus the number of concurrent calls is limited to the number of worker threads returned by System.Threading.ThreadPool.GetMaxThreads. When using several components that can each create a socket connection or a single component that can create multiple socket connections, the application may enter a state in which all of the pool threads are in use for receiving. In a scenario such as this, the remote hosts may be waiting for data from the application before sending, but the application cannot send that data because all the threads are tied up waiting for inbound data. This is particularly important for server applications that use a daemon component.

For example, say a server application 'S' has a max thread pool size of three, and clients 'A' and 'B' connect to it and each client uploads a large file. After all uploads are complete, 'S' enqueues an asynchronous read request in the thread pool for each client. Because no work is being done, the thread pool immediately consumes two threads that wait for any further data from 'A' and 'B'. While 'S' is still processing the first two files it has received, client 'C' connects and uploads a relatively small file. Similarly, once that upload has completed 'S' enqueues a third read request, and the thread pool immediately consumes the third and final thread to wait for further data from 'C'. Once 'S' completes processing any of the files, it will enqueue a send request. However, because all three threads are in use and waiting for data from the clients, the send operation cannot be completed. The entire system becomes deadlocked because each of the clients is waiting for data from the server, which cannot send that data because all of its pool threads are in turn waiting for data from the clients.

To avoid a deadlock situation such as this, it is necessary to ensure that the maximum number of socket connections an application can make is always at least one less than the number of available worker threads. One method to achieve this is to call System.Threading.ThreadPool.SetMaxThreads during the application's startup to set the maximum number of threads to a value high enough to support the application for the duration of its execution. Another option is to trap an event such as ConnectionRequest and Disconnected from each component instance with logic to manage the maximum thread pool size according to the application's current needs.

Note: Server components are designed to process events as they occur. To ensure that events are processed in a timely manner, DoEvents should be called in a loop after the server is started.

Property List


The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

ChannelsThe collection of currently open channels.
ConnectionBacklogThis property includes the maximum number of pending connections maintained by the Transmission Control Protocol (TCP)/IP subsystem.
ConnectionsA collection of currently connected Secure Shell (SSH) clients.
DefaultAuthMethodsThe supported authentication methods.
DefaultIdleTimeoutThis property includes the default idle timeout for inactive clients.
DefaultTimeoutAn initial timeout value to be used by incoming connections.
KeyboardInteractiveMessageThe instructions to send to the client during keyboard-interactive authentication.
KeyboardInteractivePromptsA collection of prompts to present to the user for keyboard-interactive authentication.
ListeningThis property indicates whether the component is listening for incoming connections on LocalPort.
LocalHostThe name of the local host or user-assigned IP interface through which connections are initiated or accepted.
LocalPortThe Transmission Control Protocol (TCP) port in the local host where the component listens.
SSHCertA certificate to be used during Secure Shell (SSH) negotiation.
SSHCompressionAlgorithmsThe comma-separated list containing all allowable compression algorithms.
SSHEncryptionAlgorithmsThe comma-separated list containing all allowable encryption algorithms.

Method List


The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

ChangeRecordLengthChanges the length of received data records.
CloseChannelCloses an existing SSHChannel .
ConfigSets or retrieves a configuration setting.
DisconnectThis method disconnects the specified client.
DoEventsThis method processes events from the internal message queue.
ExchangeKeysCauses the component to exchange a new set of session keys on the specified connection.
GetSSHParamReads a field from a Secure Shell (SSH) packet's payload.
GetSSHParamBytesReads a field from a Secure Shell (SSH) packet's payload.
OpenChannelOpens a new SSHChannel .
ResetThis method will reset the component.
SendBytesSends binary data to the specified channel.
SendChannelDataSends data over a Secure Shell (SSH) channel.
SendSSHPacketSends an encoded Secure Shell (SSH) packet to the server.
SendTextSends text to the specified channel.
SetSSHParamWrites a field to the end of a payload.
ShutdownThis method shuts down the server.
StartListeningThis method starts listening for incoming connections.
StopListeningThis method stops listening for new connections.

Event List


The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

ConnectedFired immediately after a connection completes (or fails).
ConnectionRequestThis event is fired when a request for connection comes from a remote host.
DisconnectedThis event is fired when a connection is closed.
ErrorFired when errors occur during data delivery.
LogFired once for each log message.
SSHChannelClosedFired when a channel is closed.
SSHChannelDataInFired when data are received on a Secure Shell (SSH) channel.
SSHChannelEOFFired when the remote peer signals the end of the data stream for the channel.
SSHChannelOpenedFired when a channel is successfully opened.
SSHChannelOpenRequestFired when a client attempts to open a new channel.
SSHChannelReadyToSendFired when the component is ready to send data.
SSHChannelRequestFired when the SSHHost sends a channel request to the client.
SSHChannelRequestedFired if the SSHChannelRequest was successful, any further processing for the channel request should be done here.
SSHServiceRequestFired when a client requests a service to be started.
SSHStatusFired to show the progress of the secure connection.
SSHTunnelClosedFired when a connected client attempts to close a tunnel.
SSHTunnelRequestedFired when a connected client attempts to establish a forward or reverse tunnel.
SSHUserAuthRequestFired when a client attempts to authenticate a connection.

Config Settings


The following is a list of config settings for the component with short descriptions. Click on the links for further details.

AltSSHCertCountThe number of records in the AltSSHCert configuration settings.
AltSSHCertStore[i]The name of the certificate store.
AltSSHCertStorePassword[i]The password used to open the certificate store.
AltSSHCertStoreType[i]The type of certificate store.
AltSSHCertSubject[i]The alternative certificate subject.
ClientSSHVersionString[ConnectionId]The client's version string.
FireAuthRequestAfterSigWhether to fire an informational event after the public key signature has been verified.
KeyboardInteractivePrompts[ConnectionId]Specifies custom keyboard-interactive prompts for particular connections.
KeyRenegotiationThresholdSets the threshold for the SSH Key Renegotiation.
LogLevelSpecifies the level of detail that is logged.
MaxAuthAttemptsThe maximum authentication attempts allowed before forcing a disconnect.
NegotiatedStrictKex[ConnectionId]Returns whether strict key exchange was negotiated to be used.
ServerSSHVersionStringThe SSH version string sent to connecting clients.
SSHKeepAliveCountMaxThe maximum number of keep alive packets to send without a response.
SSHKeepAliveIntervalThe interval between keep alive packets.
SSHKeyExchangeAlgorithmsSpecifies the supported key exchange algorithms.
SSHMacAlgorithmsSpecifies the supported Mac algorithms.
SSHPubKeyAuthSigAlgorithmsSpecifies the allowed signature algorithms used by a client performing public key authentication.
SSHPublicKeyAlgorithmsSpecifies the supported public key algorithms for the server's public key.
SSHVersionPatternThe pattern used to match the remote host's version string.
UserAuthBanner[ConnectionId]A custom user authentication banner.
UseStrictKeyExchangeSpecifies how strict key exchange is supported.
AllowedClientsA comma-separated list of host names or IP addresses that can access the component.
BindExclusivelyWhether or not the component considers a local port reserved for exclusive use.
BlockedClientsA comma-separated list of host names or IP addresses that cannot access the component.
CloseStreamAfterTransferIf true, the component will close the upload or download stream after the transfer.
DefaultConnectionTimeoutThe inactivity timeout applied to the SSL handshake.
InBufferSizeThe size in bytes of the incoming queue of the socket.
KeepAliveIntervalThe retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.
KeepAliveTimeThe inactivity time in milliseconds before a TCP keep-alive packet is sent.
MaxConnectionsThe maximum number of connections available.
OutBufferSizeThe size in bytes of the outgoing queue of the socket.
PreferredDHGroupBitsSize of the Diffie-Hellman group, in bits.
TcpNoDelayWhether or not to delay when sending packets.
UseBackgroundThreadWhether threads created by the component are background threads.
UseIPv6Whether to use IPv6.
BuildInfoInformation about the product's build.
GUIAvailableWhether or not a message loop is available for processing events.
LicenseInfoInformation about the current license.
MaskSensitiveDataWhether sensitive data is masked in log messages.
UseFIPSCompliantAPITells the component whether or not to use FIPS certified APIs.
UseInternalSecurityAPIWhether or not to use the system security libraries or an internal implementation.

Channels Property (SSHServer Component)

The collection of currently open channels.

Syntax

public SSHChannelMap Channels { get; }
Public ReadOnly Property Channels As SSHChannelMap

Remarks

The Secure Shell (SSH) 2.0 specification allows for multiple channels to be opened over a single Transmission Control Protocol (TCP)/IP connection. The Channels property represents the channels that are currently open. A new SSHChannel can be opened with OpenChannel, and data can be sent over it with SendChannelData.

This collection is a hashtable where the channel's Id string is used as the key to the desired Secure Shell (SSH) channel object.

This property is read-only.

Please refer to the SSHChannel type for a complete list of fields.

ConnectionBacklog Property (SSHServer Component)

This property includes the maximum number of pending connections maintained by the Transmission Control Protocol (TCP)/IP subsystem.

Syntax

public int ConnectionBacklog { get; set; }
Public Property ConnectionBacklog As Integer

Default Value

5

Remarks

This property contains the maximum number of pending connections maintained by the TCP/IP subsystem. This value reflects the SOMAXCONN option for the main listening socket. The default value for most systems is 5. You may set this property to a larger value if the server is expected to receive a large number of connections, and queuing them is desirable.

This property is not available at design time.

Connections Property (SSHServer Component)

A collection of currently connected Secure Shell (SSH) clients.

Syntax

public SSHConnectionMap Connections { get; }
Public ReadOnly Property Connections As SSHConnectionMap

Remarks

This property is a collection of currently connected clients. All of the connections may be managed using this property. Each connection is described by the different fields of the SSHConnection type.

This collection is a hashtable type of collection, in which the connection Id string is used as the key to the desired connection. You may acquire the key for a given connection through the Connected event.

This property is read-only.

Please refer to the SSHConnection type for a complete list of fields.

DefaultAuthMethods Property (SSHServer Component)

The supported authentication methods.

Syntax

public string DefaultAuthMethods { get; set; }
Public Property DefaultAuthMethods As String

Default Value

"password,publickey"

Remarks

This property specifies the supported authentication methods. The client will choose one of the supported mechanisms when authenticating to the component.

This must be a comma-separated list of values. For more information on authenticating clients, see the SSHUserAuthRequest event.

The following is a list of methods implemented by the component:

noneThis authentication method is used by most Secure Shell (SSH) clients to obtain the list of authentication methods available for the user's account. In most cases, you should not accept a request using this authentication method.
passwordAuthParam will contain the user-supplied password. If the password is correct, set Accept to True.
publickeyAuthParam will contain an SSH2 public key blob. If the user's public key is acceptable, set Accept or PartialSuccess to true. The component will then handle verifying the digital signature and will respond to the client accordingly.
keyboard-interactiveSSHUserAuthRequest will fire multiple times for keyboard-interactive authentication: It will fire once for each response sent by the client in the SSH_MSG_USERAUTH_INFO_RESPONSE packet (one time for each prompt specified by the daemon). The index of each response will be specified as a suffix in AuthMethod, with AuthParam containing the response to the corresponding prompt (e.g., keyboard-interactive-1, keyboard-interactive-2, and so on). Finally, SSHUserAuthRequest will fire one last time with AuthMethod set to "keyboard-interactive" and AuthParam set to an empty string. The daemon must set Accept to True every time to allow the authentication process to succeed.

DefaultIdleTimeout Property (SSHServer Component)

This property includes the default idle timeout for inactive clients.

Syntax

public int DefaultIdleTimeout { get; set; }
Public Property DefaultIdleTimeout As Integer

Default Value

0

Remarks

This property specifies the idle timeout (in seconds) for clients. When set to a positive value, the component will disconnect idle clients after the specified timeout.

This applies only to clients that have not sent or received data within DefaultIdleTimeout seconds.

If set to 0 (default), no idle timeout is applied.

Note: DoEvents must be called for the component to check existing connections.

DefaultTimeout Property (SSHServer Component)

An initial timeout value to be used by incoming connections.

Syntax

public int DefaultTimeout { get; set; }
Public Property DefaultTimeout As Integer

Default Value

60

Remarks

If the DefaultTimeout property is set to 0, all operations will run uninterrupted until successful completion or an error condition is encountered.

If DefaultTimeout is set to a positive value, the component will wait for the operation to complete before returning control.

The component will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not freeze and remains responsive.

If Timeout expires, and the operation is not yet complete, the component throws an exception.

Note: By default, all timeouts are inactivity timeouts, that is, the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for the DefaultTimeout property is 60 (seconds).

KeyboardInteractiveMessage Property (SSHServer Component)

The instructions to send to the client during keyboard-interactive authentication.

Syntax

public string KeyboardInteractiveMessage { get; set; }
Public Property KeyboardInteractiveMessage As String

Default Value

""

Remarks

This property should be set to the main instructions to send to the client during keyboard-interactive authentication.

KeyboardInteractivePrompts Property (SSHServer Component)

A collection of prompts to present to the user for keyboard-interactive authentication.

Syntax

public SSHPromptList KeyboardInteractivePrompts { get; }
Public Property KeyboardInteractivePrompts As SSHPromptList

Remarks

This property is a collection of prompts to present to the user during keyboard-authentication. It is used together with the KeyboardInteractiveMessage property.

Please refer to the SSHPrompt type for a complete list of fields.

Listening Property (SSHServer Component)

This property indicates whether the component is listening for incoming connections on LocalPort.

Syntax

public bool Listening { get; }
Public ReadOnly Property Listening As Boolean

Default Value

False

Remarks

This property indicates whether the component is listening for connections on the port specified by the LocalPort property. Use the StartListening and StopListening methods to control whether the component is listening.

This property is read-only and not available at design time.

LocalHost Property (SSHServer Component)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

public string LocalHost { get; set; }
Public Property LocalHost As String

Default Value

""

Remarks

This property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the component initiate connections (or accept in the case of server components) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

If the component is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).

Note: LocalHost is not persistent. You must always set it in code, and never in the property window.

LocalPort Property (SSHServer Component)

The Transmission Control Protocol (TCP) port in the local host where the component listens.

Syntax

public int LocalPort { get; set; }
Public Property LocalPort As Integer

Default Value

22

Remarks

The LocalPort property must be set before TCPServer starts listening. If its value is 0, then the TCP/IP subsystem picks a port number at random. The port number can be found by checking the value of the LocalPort property after TCPServer is in listening mode (after successfully assigning True to the Listening property).

The service port is not shared among servers (i.e., only one TCPServer can be 'listening' on a particular port at one time).

SSHCert Property (SSHServer Component)

A certificate to be used during Secure Shell (SSH) negotiation.

Syntax

public Certificate SSHCert { get; set; }
Public Property SSHCert As Certificate

Remarks

The digital certificate that the server will use during SSH negotiation. A certificate with a private key is required for session authentication and encryption.

This is the server's certificate, and must be set before setting Listening to True.

Please refer to the Certificate type for a complete list of fields.

SSHCompressionAlgorithms Property (SSHServer Component)

The comma-separated list containing all allowable compression algorithms.

Syntax

public string SSHCompressionAlgorithms { get; set; }
Public Property SSHCompressionAlgorithms As String

Default Value

"none,zlib"

Remarks

During the Secure Shell (SSH) handshake, this list will be used to negotiate the compression algorithm to be used between the client and server. This list is used for both directions: client to server and server to client. When negotiating algorithms, each side sends a list of all algorithms it supports or allows. The algorithm chosen for each direction is the first algorithm to appear in the sender's list that the receiver supports. Therefore, it is important to list multiple algorithms in preferential order. If no algorithm can be agreed on, the component will raise an error and the connection will be aborted.

At least one supported algorithm must appear in this list. The following compression algorithms are supported by the component:

  • zlib
  • zlib@openssh.com
  • none

SSHEncryptionAlgorithms Property (SSHServer Component)

The comma-separated list containing all allowable encryption algorithms.

Syntax

public string SSHEncryptionAlgorithms { get; set; }
Public Property SSHEncryptionAlgorithms As String

Default Value

"aes256-ctr,aes192-ctr,aes128-ctr,3des-ctr,arcfour256,arcfour128,arcfour,aes256-gcm@openssh.com,aes128-gcm@openssh.com,chacha20-poly1305@openssh.com"

Remarks

During the Secure Shell (SSH) handshake, this list will be used to negotiate the encryption algorithm to be used between the client and server. This list is used for both directions: client to server and server to client. When negotiating algorithms, each side sends a list of all algorithms it supports or allows. The algorithm chosen for each direction is the first algorithm to appear in the sender's list that the receiver supports. Therefore, it is important to list multiple algorithms in preferential order. If no algorithm can be agreed on, the component will raise an error and the connection will be aborted.

At least one supported algorithm must appear in this list. The following encryption algorithms are supported by the component:

aes256-ctr256-bit AES encryption in CTR mode.
aes256-cbc256-bit AES encryption in CBC mode.
aes192-ctr192-bit AES encryption in CTR mode.
aes192-cbc192-bit AES encryption in CBC mode.
aes128-ctr128-bit AES encryption in CTR mode.
aes128-cbc128-bit AES encryption in CBC mode.
3des-ctr192-bit (3-key) triple DES encryption in CTR mode.
3des-cbc192-bit (3-key) triple DES encryption in CBC mode.
cast128-cbcCAST-128 encryption.
blowfish-cbcBlowfish encryption.
arcfourARC4 encryption.
arcfour128128-bit ARC4 encryption.
arcfour256256-bit ARC4 encryption.
aes256-gcm@openssh.com256-bit AES encryption in GCM mode.
aes128-gcm@openssh.com128-bit AES encryption in GCM mode.
chacha20-poly1305@openssh.comChaCha20 with Poly1305-AES encryption.

ChangeRecordLength Method (SSHServer Component)

Changes the length of received data records.

Syntax

public void ChangeRecordLength(string channelId, int recordLength);

Async Version
public async Task ChangeRecordLength(string channelId, int recordLength);
public async Task ChangeRecordLength(string channelId, int recordLength, CancellationToken cancellationToken);
Public Sub ChangeRecordLength(ByVal ChannelId As String, ByVal RecordLength As Integer)

Async Version
Public Sub ChangeRecordLength(ByVal ChannelId As String, ByVal RecordLength As Integer) As Task
Public Sub ChangeRecordLength(ByVal ChannelId As String, ByVal RecordLength As Integer, cancellationToken As CancellationToken) As Task

Remarks

This method defines the length of data records to be received (in bytes) for the specified ChannelId.

If RecordLength is set to a positive value, the component will accumulate data until RecordLength bytes of data is received and only then will it fire the SSHChannelDataIn event with data of length RecordLength. This allows data to be received as records of known length. This method can be called at any time to change the record length, including within the DataIn event.

A value of 0 (default) means this functionality is not used.

CloseChannel Method (SSHServer Component)

Closes an existing SSHChannel .

Syntax

public void CloseChannel(string channelId);

Async Version
public async Task CloseChannel(string channelId);
public async Task CloseChannel(string channelId, CancellationToken cancellationToken);
Public Sub CloseChannel(ByVal ChannelId As String)

Async Version
Public Sub CloseChannel(ByVal ChannelId As String) As Task
Public Sub CloseChannel(ByVal ChannelId As String, cancellationToken As CancellationToken) As Task

Remarks

ChannelId is the identifier for the Secure Shell (SSH) channel to be closed.

Config Method (SSHServer Component)

Sets or retrieves a configuration setting.

Syntax

public string Config(string configurationString);

Async Version
public async Task<string> Config(string configurationString);
public async Task<string> Config(string configurationString, CancellationToken cancellationToken);
Public Function Config(ByVal ConfigurationString As String) As String

Async Version
Public Function Config(ByVal ConfigurationString As String) As Task(Of String)
Public Function Config(ByVal ConfigurationString As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Disconnect Method (SSHServer Component)

This method disconnects the specified client.

Syntax

public void Disconnect(string connectionId);

Async Version
public async Task Disconnect(string connectionId);
public async Task Disconnect(string connectionId, CancellationToken cancellationToken);
Public Sub Disconnect(ByVal ConnectionId As String)

Async Version
Public Sub Disconnect(ByVal ConnectionId As String) As Task
Public Sub Disconnect(ByVal ConnectionId As String, cancellationToken As CancellationToken) As Task

Remarks

Calling this method will disconnect the client specified by the ConnectionId parameter.

DoEvents Method (SSHServer Component)

This method processes events from the internal message queue.

Syntax

public void DoEvents();

Async Version
public async Task DoEvents();
public async Task DoEvents(CancellationToken cancellationToken);
Public Sub DoEvents()

Async Version
Public Sub DoEvents() As Task
Public Sub DoEvents(cancellationToken As CancellationToken) As Task

Remarks

When DoEvents is called, the component processes any available events. If no events are available, it waits for a preset period of time, and then returns.

ExchangeKeys Method (SSHServer Component)

Causes the component to exchange a new set of session keys on the specified connection.

Syntax

public void ExchangeKeys(string connectionId);

Async Version
public async Task ExchangeKeys(string connectionId);
public async Task ExchangeKeys(string connectionId, CancellationToken cancellationToken);
Public Sub ExchangeKeys(ByVal ConnectionId As String)

Async Version
Public Sub ExchangeKeys(ByVal ConnectionId As String) As Task
Public Sub ExchangeKeys(ByVal ConnectionId As String, cancellationToken As CancellationToken) As Task

Remarks

Secure Shell (SSH) key renegotiation can be initiated by either end of an established SSH connection. ExchangeKeys allows the server to start such a renegotiation with the client. During this process, SSHStatus events will fire containing updates regarding the key negotiation process.

The SSH 2.0 specification recommends that key renegotiation be done once for 2 gigabytes (GB) of data processed by the connection, or once every day. This makes it more difficult to break the security of data-intensive or long-lived connections.

GetSSHParam Method (SSHServer Component)

Reads a field from a Secure Shell (SSH) packet's payload.

Syntax

public string GetSSHParam(byte[] payload, string field);

Async Version
public async Task<string> GetSSHParam(byte[] payload, string field);
public async Task<string> GetSSHParam(byte[] payload, string field, CancellationToken cancellationToken);
Public Function GetSSHParam(ByVal Payload As String, ByVal Field As String) As String

Async Version
Public Function GetSSHParam(ByVal Payload As String, ByVal Field As String) As Task(Of String)
Public Function GetSSHParam(ByVal Payload As String, ByVal Field As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

This method is used to read the value of a particular field from an SSH packet's payload. Payload should contain the full payload of a packet received by an event such as SSHChannelRequest. Field is the name of a field to be read out of the packet.

The following is a list of the names of well-known channel request field names and their encodings:

ChannelId (int32)The Id of the channel that received the packet.
RequestType (string)The type of channel requested.
WantsReply (boolean)Whether or not the client wants a reply to the request.

The remaining fields that are available in the payload are dependent on the value of RequestType.

pty-req

Pty-req is a request to open a pseudo terminal on the specified channel. The following fields are available:

TerminalType (string)The type of terminal being requested (e.g., "vt100").
TerminalWidthCharacters (int32)The width, in characters, of the terminal to be opened.
TerminalHeightRows (int32)The height, in rows, of the terminal to be opened.
TerminalWidthPixels (int32)The width, in pixels, of the terminal to be opened.
TerminalHeightPixels (int32)The height, in pixels, of the terminal to be opened.
TerminalModes (string)A list of op-val (int32-byte) encoded modes to be used by the terminal.

x11-req

X11-req is a request to forward x11 sessions over a channel. The following fields are available:

SingleConnection (boolean)Disallows more than one connection to be forwarded by the channel.
X11AuthProtocol (string)The authentication protocol to be used (e.g., "MIT-MAGIC-COOKIE-1").
X11AuthCookie (string)A hexadecimal-encoded cookie to be used for authentication.
X11ScreenNumber (int32)The x11 screen number to be used.

env

Env is a request to set an environment variable to be passed into a shell that may be started later. The following fields are available:

VariableName (string)The name of the variable to be set.
VariableValue (string)The value of the variable to be set.

exec

Exec is a request to execute a command on the channel using the authenticated user's shell. The following field is available:

Command (string)The command to be executed.

subsystem

Subsystem is a request to start a subsystem on the specified channel. The following field is available:

Subsystem (string)The name of the subsystem to be started (e.g., "sftp").

xon-xoff

Xon-xoff instructs the server to allow or disallow control-S/control-Q style flow control. The following field is available:

ClientCanDo (boolean)Whether or not the server should enable flow control.

signal

Sends a signal to the remote process/service. The following field is available:

SignalName (string)The name of the signal to be sent.

If the packet type is not well known, Field should start with the special character "%" and contain a comma-separated list of field types as defined in SetSSHParam. For example, reading out the X11AuthProtocol of an x11-req payload, you can use "%s,f".

Note: The return value is a string encoded the same way as the FieldValue param in SetSSHParam.

GetSSHParamBytes Method (SSHServer Component)

Reads a field from a Secure Shell (SSH) packet's payload.

Syntax

public byte[] GetSSHParamBytes(byte[] payload, string field);

Async Version
public async Task<byte[]> GetSSHParamBytes(byte[] payload, string field);
public async Task<byte[]> GetSSHParamBytes(byte[] payload, string field, CancellationToken cancellationToken);
Public Function GetSSHParamBytes(ByVal Payload As String, ByVal Field As String) As String

Async Version
Public Function GetSSHParamBytes(ByVal Payload As String, ByVal Field As String) As Task(Of String)
Public Function GetSSHParamBytes(ByVal Payload As String, ByVal Field As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

This method is the same as calling GetSSHParam, but it returns raw bytes instead of strings.

OpenChannel Method (SSHServer Component)

Opens a new SSHChannel .

Syntax

public string OpenChannel(string connectionId, string channelType);

Async Version
public async Task<string> OpenChannel(string connectionId, string channelType);
public async Task<string> OpenChannel(string connectionId, string channelType, CancellationToken cancellationToken);
Public Function OpenChannel(ByVal ConnectionId As String, ByVal ChannelType As String) As String

Async Version
Public Function OpenChannel(ByVal ConnectionId As String, ByVal ChannelType As String) As Task(Of String)
Public Function OpenChannel(ByVal ConnectionId As String, ByVal ChannelType As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

The Secure Shell (SSH) 2.0 specification allows for multiple channels to be opened over a single Transmission Control Protocol (TCP)/IP connection. The Channels property represents the channels that are currently open. A new SSHChannel can be opened with OpenChannel, and data can be sent over it with SendChannelData.

ChannelType represents the type of Secure Shell (SSH) channel to be opened. The most common type of channel is "session".

If the call to OpenChannel succeeds, an SSHChannel will be created and added to the Channels collection.

Reset Method (SSHServer Component)

This method will reset the component.

Syntax

public void Reset();

Async Version
public async Task Reset();
public async Task Reset(CancellationToken cancellationToken);
Public Sub Reset()

Async Version
Public Sub Reset() As Task
Public Sub Reset(cancellationToken As CancellationToken) As Task

Remarks

This method will reset the component's properties to their default values.

SendBytes Method (SSHServer Component)

Sends binary data to the specified channel.

Syntax

public void SendBytes(string channelId, byte[] data);

Async Version
public async Task SendBytes(string channelId, byte[] data);
public async Task SendBytes(string channelId, byte[] data, CancellationToken cancellationToken);
Public Sub SendBytes(ByVal ChannelId As String, ByVal Data As String)

Async Version
Public Sub SendBytes(ByVal ChannelId As String, ByVal Data As String) As Task
Public Sub SendBytes(ByVal ChannelId As String, ByVal Data As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends binary data to the channel identified by ChannelId. To send text, use the SendText method instead.

SendChannelData Method (SSHServer Component)

Sends data over a Secure Shell (SSH) channel.

Syntax

public void SendChannelData(string channelId, byte[] data);

Async Version
public async Task SendChannelData(string channelId, byte[] data);
public async Task SendChannelData(string channelId, byte[] data, CancellationToken cancellationToken);
Public Sub SendChannelData(ByVal ChannelId As String, ByVal Data As String)

Async Version
Public Sub SendChannelData(ByVal ChannelId As String, ByVal Data As String) As Task
Public Sub SendChannelData(ByVal ChannelId As String, ByVal Data As String, cancellationToken As CancellationToken) As Task

Remarks

This method can be used to send arbitrary data to the channel with the specified ChannelId.

SendSSHPacket Method (SSHServer Component)

Sends an encoded Secure Shell (SSH) packet to the server.

Syntax

public void SendSSHPacket(string channelId, int packetType, byte[] payload);

Async Version
public async Task SendSSHPacket(string channelId, int packetType, byte[] payload);
public async Task SendSSHPacket(string channelId, int packetType, byte[] payload, CancellationToken cancellationToken);
Public Sub SendSSHPacket(ByVal ChannelId As String, ByVal PacketType As Integer, ByVal Payload As String)

Async Version
Public Sub SendSSHPacket(ByVal ChannelId As String, ByVal PacketType As Integer, ByVal Payload As String) As Task
Public Sub SendSSHPacket(ByVal ChannelId As String, ByVal PacketType As Integer, ByVal Payload As String, cancellationToken As CancellationToken) As Task

Remarks

This method can be used to send a previously built SSH payload to the server. ChannelId identifies the channel that will receive the packet.

PacketType identifies what kind of packet is to be sent. Payload should contain the payload of the packet, which can be built by successive calls to SetSSHParam.

When SendSSHPacket is called, the component will finish building the packet, encrypt it for transport, and send it to the server.

SendText Method (SSHServer Component)

Sends text to the specified channel.

Syntax

public void SendText(string channelId, string text);

Async Version
public async Task SendText(string channelId, string text);
public async Task SendText(string channelId, string text, CancellationToken cancellationToken);
Public Sub SendText(ByVal ChannelId As String, ByVal Text As String)

Async Version
Public Sub SendText(ByVal ChannelId As String, ByVal Text As String) As Task
Public Sub SendText(ByVal ChannelId As String, ByVal Text As String, cancellationToken As CancellationToken) As Task

Remarks

This method sends text to the client identified by ChannelId. To send binary data, use the SendBytes method instead.

SetSSHParam Method (SSHServer Component)

Writes a field to the end of a payload.

Syntax

public byte[] SetSSHParam(byte[] payload, string fieldType, string fieldValue);

Async Version
public async Task<byte[]> SetSSHParam(byte[] payload, string fieldType, string fieldValue);
public async Task<byte[]> SetSSHParam(byte[] payload, string fieldType, string fieldValue, CancellationToken cancellationToken);
Public Function SetSSHParam(ByVal Payload As String, ByVal FieldType As String, ByVal FieldValue As String) As String

Async Version
Public Function SetSSHParam(ByVal Payload As String, ByVal FieldType As String, ByVal FieldValue As String) As Task(Of String)
Public Function SetSSHParam(ByVal Payload As String, ByVal FieldType As String, ByVal FieldValue As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

This method is used to build the payload portion of a Secure Shell (SSH) packet to be sent later by a call to SendSSHPacket. Payload should contain the result of a previous call to SetSSHParam. FieldType is a string defining the type of field to be written to the packet. FieldValue should be the string representation of the field to be written.

The following is a list of supported field types and a description of how FieldValue should be encoded:

sA plaintext string containing the default system encoding of the data.
sbA string containing the hex-encoded data (e.g., "A1B23C")
mA variable-length large integer, encoded as a textual representation of the value (e.g., "1234").
iA 32-bit integer, encoded as a textual representation of the value (e.g., "1234").
lA 64-bit integer, encoded as a textual representation of the value (e.g., "1234").
bA single byte, encoded as a textual representation of the value (e.g., "123").
fA boolean flag, encoded as a textual representation of the value (e.g., 'True' or 'False')

Note: Integer values may be hexadecimal encoded by prefixing "0x" to the beginning of the string; otherwise, the value is assumed to be Base10.

Shutdown Method (SSHServer Component)

This method shuts down the server.

Syntax

public void Shutdown();

Async Version
public async Task Shutdown();
public async Task Shutdown(CancellationToken cancellationToken);
Public Sub Shutdown()

Async Version
Public Sub Shutdown() As Task
Public Sub Shutdown(cancellationToken As CancellationToken) As Task

Remarks

This method shuts down the server. Calling this method is equivalent to calling StopListening and then breaking every client connection by calling Disconnect.

StartListening Method (SSHServer Component)

This method starts listening for incoming connections.

Syntax

public void StartListening();

Async Version
public async Task StartListening();
public async Task StartListening(CancellationToken cancellationToken);
Public Sub StartListening()

Async Version
Public Sub StartListening() As Task
Public Sub StartListening(cancellationToken As CancellationToken) As Task

Remarks

This method begins listening for incoming connections on the port specified by LocalPort. Once listening, events will fire as new clients connect and data are transferred.

To stop listening for new connections, call StopListening. To stop listening for new connections and to disconnect all existing clients, call Shutdown.

StopListening Method (SSHServer Component)

This method stops listening for new connections.

Syntax

public void StopListening();

Async Version
public async Task StopListening();
public async Task StopListening(CancellationToken cancellationToken);
Public Sub StopListening()

Async Version
Public Sub StopListening() As Task
Public Sub StopListening(cancellationToken As CancellationToken) As Task

Remarks

This method stops listening for new connections. After being called, any new connection attempts will be rejected. Calling this method does not disconnect existing connections.

To stop listening and to disconnect all existing clients, call Shutdown instead.

Connected Event (SSHServer Component)

Fired immediately after a connection completes (or fails).

Syntax

public event OnConnectedHandler OnConnected;

public delegate void OnConnectedHandler(object sender, SSHServerConnectedEventArgs e);

public class SSHServerConnectedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int StatusCode { get; }
  public string Description { get; }
  public int CertStoreType { get; set; }
  public string CertStore { get; set; }
  public string CertPassword { get; set; }
  public string CertSubject { get; set; }
}
Public Event OnConnected As OnConnectedHandler

Public Delegate Sub OnConnectedHandler(sender As Object, e As SSHServerConnectedEventArgs)

Public Class SSHServerConnectedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
  Public Property CertStoreType As Integer
  Public Property CertStore As String
  Public Property CertPassword As String
  Public Property CertSubject As String
End Class

Remarks

If the connection is made normally, StatusCode is 0, and Description is "OK".

If the connection fails, StatusCode has the error code returned by the system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

ConnectionId is the connection Id of the client requesting the connection.

CertStoreType is the store type of the alternate certificate to use for this connection. The component supports both public and private keys in a variety of formats. When the cstAuto value is used, the component will automatically determine the type. This field can take one of the following values:

0 (cstUser - default)For Windows, this specifies that the certificate store is a certificate store owned by the current user.

Note: This store type is not available in Java.

1 (cstMachine)For Windows, this specifies that the certificate store is a machine store.

Note: This store type is not available in Java.

2 (cstPFXFile)The certificate store is the name of a PFX (PKCS#12) file containing certificates.
3 (cstPFXBlob)The certificate store is a string (binary or Base64-encoded) representing a certificate store in PFX (PKCS#12) format.
4 (cstJKSFile)The certificate store is the name of a Java Key Store (JKS) file containing certificates.

Note: This store type is only available in Java.

5 (cstJKSBlob)The certificate store is a string (binary or Base64-encoded) representing a certificate store in Java Key Store (JKS) format.

Note: This store type is only available in Java.

6 (cstPEMKeyFile)The certificate store is the name of a PEM-encoded file that contains a private key and an optional certificate.
7 (cstPEMKeyBlob)The certificate store is a string (binary or Base64-encoded) that contains a private key and an optional certificate.
8 (cstPublicKeyFile)The certificate store is the name of a file that contains a PEM- or DER-encoded public key certificate.
9 (cstPublicKeyBlob)The certificate store is a string (binary or Base64-encoded) that contains a PEM- or DER-encoded public key certificate.
10 (cstSSHPublicKeyBlob)The certificate store is a string (binary or Base64-encoded) that contains an SSH-style public key.
11 (cstP7BFile)The certificate store is the name of a PKCS#7 file containing certificates.
12 (cstP7BBlob)The certificate store is a string (binary) representing a certificate store in PKCS#7 format.
13 (cstSSHPublicKeyFile)The certificate store is the name of a file that contains an SSH-style public key.
14 (cstPPKFile)The certificate store is the name of a file that contains a PPK (PuTTY Private Key).
15 (cstPPKBlob)The certificate store is a string (binary) that contains a PPK (PuTTY Private Key).
16 (cstXMLFile)The certificate store is the name of a file that contains a certificate in XML format.
17 (cstXMLBlob)The certificate store is a string that contains a certificate in XML format.
18 (cstJWKFile)The certificate store is the name of a file that contains a JWK (JSON Web Key).
19 (cstJWKBlob)The certificate store is a string that contains a JWK (JSON Web Key).
21 (cstBCFKSFile)The certificate store is the name of a file that contains a BCFKS (Bouncy Castle FIPS Key Store).

Note: This store type is only available in Java and .NET.

22 (cstBCFKSBlob)The certificate store is a string (binary or Base64-encoded) representing a certificate store in BCFKS (Bouncy Castle FIPS Key Store) format.

Note: This store type is only available in Java and .NET.

23 (cstPKCS11)The certificate is present on a physical security key accessible via a PKCS#11 interface.

To use a security key, the necessary data must first be collected using the CertMgr component. The ListStoreCertificates method may be called after setting CertStoreType to cstPKCS11, CertStorePassword to the PIN, and CertStore to the full path of the PKCS#11 DLL. The certificate information returned in the CertList event's CertEncoded parameter may be saved for later use.

When using a certificate, pass the previously saved security key information as the Store and set StorePassword to the PIN.

Code Example. SSH Authentication with Security Key: certmgr.CertStoreType = CertStoreTypes.cstPKCS11; certmgr.OnCertList += (s, e) => { secKeyBlob = e.CertEncoded; }; certmgr.CertStore = @"C:\Program Files\OpenSC Project\OpenSC\pkcs11\opensc-pkcs11.dll"; certmgr.CertStorePassword = "123456"; //PIN certmgr.ListStoreCertificates(); sftp.SSHCert = new Certificate(CertStoreTypes.cstPKCS11, secKeyBlob, "123456", "*"); sftp.SSHUser = "test"; sftp.SSHLogon("myhost", 22);

99 (cstAuto)The store type is automatically detected from the input data. This setting may be used with both public and private keys and can detect any of the supported formats automatically.

CertStore is the store name or location of the alternate certificate to use for this connection.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

MYA certificate store holding personal certificates with their associated private keys.
CACertifying authority certificates.
ROOTRoot certificates.

When the certificate store type is cstPFXFile, this property must be set to the name of the file. When the type is cstPFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

CertPassword is the password of the certificate store containing the alternate certificate to use for this connection.

CertSubject is the subject of the alternate certificate to use for this connection.

The special value * matches any subject and will select the first certificate in the store. The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:

FieldMeaning
CNCommon Name. This is commonly a hostname like www.server.com.
OOrganization
OUOrganizational Unit
LLocality
SState
CCountry
EEmail Address

If a field value contains a comma, it must be quoted.

ConnectionRequest Event (SSHServer Component)

This event is fired when a request for connection comes from a remote host.

Syntax

public event OnConnectionRequestHandler OnConnectionRequest;

public delegate void OnConnectionRequestHandler(object sender, SSHServerConnectionRequestEventArgs e);

public class SSHServerConnectionRequestEventArgs : EventArgs {
  public string Address { get; }
  public int Port { get; }
  public bool Accept { get; set; }
}
Public Event OnConnectionRequest As OnConnectionRequestHandler

Public Delegate Sub OnConnectionRequestHandler(sender As Object, e As SSHServerConnectionRequestEventArgs)

Public Class SSHServerConnectionRequestEventArgs Inherits EventArgs
  Public ReadOnly Property Address As String
  Public ReadOnly Property Port As Integer
  Public Property Accept As Boolean
End Class

Remarks

This event indicates an incoming connection. The connection is accepted by default. Address and Port will contain information about the remote host requesting the inbound connection. If you want to refuse it, you can set the Accept parameter to False.

Disconnected Event (SSHServer Component)

This event is fired when a connection is closed.

Syntax

public event OnDisconnectedHandler OnDisconnected;

public delegate void OnDisconnectedHandler(object sender, SSHServerDisconnectedEventArgs e);

public class SSHServerDisconnectedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int StatusCode { get; }
  public string Description { get; }
}
Public Event OnDisconnected As OnDisconnectedHandler

Public Delegate Sub OnDisconnectedHandler(sender As Object, e As SSHServerDisconnectedEventArgs)

Public Class SSHServerDisconnectedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class

Remarks

If the connection is broken normally, StatusCode is 0, and Description is "OK".

If the connection is broken for any other reason, StatusCode has the error code returned by the system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

Error Event (SSHServer Component)

Fired when errors occur during data delivery.

Syntax

public event OnErrorHandler OnError;

public delegate void OnErrorHandler(object sender, SSHServerErrorEventArgs e);

public class SSHServerErrorEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int ErrorCode { get; }
  public string Description { get; }
}
Public Event OnError As OnErrorHandler

Public Delegate Sub OnErrorHandler(sender As Object, e As SSHServerErrorEventArgs)

Public Class SSHServerErrorEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ErrorCode As Integer
  Public ReadOnly Property Description As String
End Class

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component throws an exception.

ConnectionId contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

ErrorCode contains an error code and Description contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Log Event (SSHServer Component)

Fired once for each log message.

Syntax

public event OnLogHandler OnLog;

public delegate void OnLogHandler(object sender, SSHServerLogEventArgs e);

public class SSHServerLogEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int LogLevel { get; }
  public string Message { get; }
  public string LogType { get; }
}
Public Event OnLog As OnLogHandler

Public Delegate Sub OnLogHandler(sender As Object, e As SSHServerLogEventArgs)

Public Class SSHServerLogEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property LogLevel As Integer
  Public ReadOnly Property Message As String
  Public ReadOnly Property LogType As String
End Class

Remarks

Fired once for each log message generated by the component. The verbosity is controlled by the LogLevel setting.

LogLevel indicates the detail level of the message. Possible values are as follows:

0 (None) No messages are logged.
1 (Info - Default) Informational events such as Secure Shell (SSH) handshake messages are logged.
2 (Verbose) Detailed data such as individual packet information are logged.
3 (Debug) Debug data including all relevant sent and received bytes are logged.

Message is the log message.

LogType is reserved for future use.

ConnectionId specifies the connection to which the log message is applicable.

SSHChannelClosed Event (SSHServer Component)

Fired when a channel is closed.

Syntax

public event OnSSHChannelClosedHandler OnSSHChannelClosed;

public delegate void OnSSHChannelClosedHandler(object sender, SSHServerSSHChannelClosedEventArgs e);

public class SSHServerSSHChannelClosedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ChannelId { get; }
}
Public Event OnSSHChannelClosed As OnSSHChannelClosedHandler

Public Delegate Sub OnSSHChannelClosedHandler(sender As Object, e As SSHServerSSHChannelClosedEventArgs)

Public Class SSHServerSSHChannelClosedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ChannelId As String
End Class

Remarks

The SSHChannelClosed event is fired when a channel is closed on a Secure Shell (SSH) connection.

ConnectionId identifies the connection. ChannelId identifies the channel.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHChannelDataIn Event (SSHServer Component)

Fired when data are received on a Secure Shell (SSH) channel.

Syntax

public event OnSSHChannelDataInHandler OnSSHChannelDataIn;

public delegate void OnSSHChannelDataInHandler(object sender, SSHServerSSHChannelDataInEventArgs e);

public class SSHServerSSHChannelDataInEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ChannelId { get; }
  public string Data { get; }
public byte[] DataB { get; } }
Public Event OnSSHChannelDataIn As OnSSHChannelDataInHandler

Public Delegate Sub OnSSHChannelDataInHandler(sender As Object, e As SSHServerSSHChannelDataInEventArgs)

Public Class SSHServerSSHChannelDataInEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ChannelId As String
  Public ReadOnly Property Data As String
Public ReadOnly Property DataB As Byte() End Class

Remarks

Whenever a client sends data to an SSH channel, the SSHChannelDataIn event will fire. ChannelId will identify the channel receiving data. Data will contain the raw data being received.

ConnectionId identifies the connection. ChannelId identifies the channel.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHChannelEOF Event (SSHServer Component)

Fired when the remote peer signals the end of the data stream for the channel.

Syntax

public event OnSSHChannelEOFHandler OnSSHChannelEOF;

public delegate void OnSSHChannelEOFHandler(object sender, SSHServerSSHChannelEOFEventArgs e);

public class SSHServerSSHChannelEOFEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ChannelId { get; }
}
Public Event OnSSHChannelEOF As OnSSHChannelEOFHandler

Public Delegate Sub OnSSHChannelEOFHandler(sender As Object, e As SSHServerSSHChannelEOFEventArgs)

Public Class SSHServerSSHChannelEOFEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ChannelId As String
End Class

Remarks

The SSHChannelEOF event is fired when the end of the data stream for a channel on a Sescure Shell (SSH) connection is reached.

ConnectionId identifies the connection. ChannelId identifies the channel.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHChannelOpened Event (SSHServer Component)

Fired when a channel is successfully opened.

Syntax

public event OnSSHChannelOpenedHandler OnSSHChannelOpened;

public delegate void OnSSHChannelOpenedHandler(object sender, SSHServerSSHChannelOpenedEventArgs e);

public class SSHServerSSHChannelOpenedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ChannelId { get; }
}
Public Event OnSSHChannelOpened As OnSSHChannelOpenedHandler

Public Delegate Sub OnSSHChannelOpenedHandler(sender As Object, e As SSHServerSSHChannelOpenedEventArgs)

Public Class SSHServerSSHChannelOpenedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ChannelId As String
End Class

Remarks

The SSHChannelOpened event is fired when a channel is successfully opened on a Secure Shell (SSH) connection.

ConnectionId identifies the connection. ChannelId identifies the channel.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHChannelOpenRequest Event (SSHServer Component)

Fired when a client attempts to open a new channel.

Syntax

public event OnSSHChannelOpenRequestHandler OnSSHChannelOpenRequest;

public delegate void OnSSHChannelOpenRequestHandler(object sender, SSHServerSSHChannelOpenRequestEventArgs e);

public class SSHServerSSHChannelOpenRequestEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ChannelId { get; }
  public string Service { get; }
  public string Parameters { get; }
public byte[] ParametersB { get; } public bool Accept { get; set; } }
Public Event OnSSHChannelOpenRequest As OnSSHChannelOpenRequestHandler

Public Delegate Sub OnSSHChannelOpenRequestHandler(sender As Object, e As SSHServerSSHChannelOpenRequestEventArgs)

Public Class SSHServerSSHChannelOpenRequestEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ChannelId As String
  Public ReadOnly Property Service As String
  Public ReadOnly Property Parameters As String
Public ReadOnly Property ParametersB As Byte() Public Property Accept As Boolean End Class

Remarks

This event is fired whenever a client attempts to open a new channel for a given connection. ChannelId will contain the Id of the channel to be created. Service will identify the type of channel that is being requested (e.g., "session"). Set Accept to True to accept the channel open request.

ConnectionId identifies the connection. ChannelId identifies the channel.

If the channel open request contains extra information, it will be contained in Parameters; you can extract data from it using GetSSHParam and GetSSHParamBytes. The most common example of a request with parameters would be a request with Service set to "direct-tcpip" (for Secure Shell (SSH) tunneling); in that case Parameters will contain the host to connect (string), the port to connect (int), the originator IP address (string), and the originator Transmission Control Protocol (TCP) port (int).

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHChannelReadyToSend Event (SSHServer Component)

Fired when the component is ready to send data.

Syntax

public event OnSSHChannelReadyToSendHandler OnSSHChannelReadyToSend;

public delegate void OnSSHChannelReadyToSendHandler(object sender, SSHServerSSHChannelReadyToSendEventArgs e);

public class SSHServerSSHChannelReadyToSendEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ChannelId { get; }
}
Public Event OnSSHChannelReadyToSend As OnSSHChannelReadyToSendHandler

Public Delegate Sub OnSSHChannelReadyToSendHandler(sender As Object, e As SSHServerSSHChannelReadyToSendEventArgs)

Public Class SSHServerSSHChannelReadyToSendEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ChannelId As String
End Class

Remarks

This event fires when data can be sent over the Secure Shell (SSH) Channel specified by ChannelId for the connection specified by ConnectionId.

When a channel is opened, this event will fire once the channel is ready and data can be sent.

When Timeout is set to 0 (asynchronous) sending data may result in an error if the channel or underlying socket cannot accept more data to send. Monitor SSHChannelReadyToSend or ReadyToSend to determine when data can be sent again.

When Timeout is set to a positive value, the component will block when sending data until the data can be successfully sent and SSHChannelReadyToSend and ReadyToSend do not need to be monitored.

SSHChannelRequest Event (SSHServer Component)

Fired when the SSHHost sends a channel request to the client.

Syntax

public event OnSSHChannelRequestHandler OnSSHChannelRequest;

public delegate void OnSSHChannelRequestHandler(object sender, SSHServerSSHChannelRequestEventArgs e);

public class SSHServerSSHChannelRequestEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ChannelId { get; }
  public string RequestType { get; }
  public string Packet { get; }
public byte[] PacketB { get; } public bool Success { get; set; } }
Public Event OnSSHChannelRequest As OnSSHChannelRequestHandler

Public Delegate Sub OnSSHChannelRequestHandler(sender As Object, e As SSHServerSSHChannelRequestEventArgs)

Public Class SSHServerSSHChannelRequestEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ChannelId As String
  Public ReadOnly Property RequestType As String
  Public ReadOnly Property Packet As String
Public ReadOnly Property PacketB As Byte() Public Property Success As Boolean End Class

Remarks

The SSHHost may send requests that affect the status of a particular SSHChannel. Some requests will be automatically handled by the component. Others, however, may need the attention of the user to be dealt with properly within the scope of the application.

ConnectionId identifies the connection.

ChannelId identifies the channel receiving the request.

Type will contain the type of the request. These types depend on the type of the channel. For example, a "session" channel executing a command on the remote shell may receive an "exit-status" request containing the return code of that command.

RequestData contains the remainder of the original Secure Shell (SSH) packet. If the request type has specific parameters, they can be parsed out of this data.

Success should be used to instruct the component to respond to the request with either a success or failure notification. If the request is successful, SSHChannelRequested will fire with the same information in case the request requires further processing.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHChannelRequested Event (SSHServer Component)

Fired if the SSHChannelRequest was successful, any further processing for the channel request should be done here.

Syntax

public event OnSSHChannelRequestedHandler OnSSHChannelRequested;

public delegate void OnSSHChannelRequestedHandler(object sender, SSHServerSSHChannelRequestedEventArgs e);

public class SSHServerSSHChannelRequestedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string ChannelId { get; }
  public string RequestType { get; }
  public string Packet { get; }
public byte[] PacketB { get; } }
Public Event OnSSHChannelRequested As OnSSHChannelRequestedHandler

Public Delegate Sub OnSSHChannelRequestedHandler(sender As Object, e As SSHServerSSHChannelRequestedEventArgs)

Public Class SSHServerSSHChannelRequestedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property ChannelId As String
  Public ReadOnly Property RequestType As String
  Public ReadOnly Property Packet As String
Public ReadOnly Property PacketB As Byte() End Class

Remarks

The SSHHost may send requests that affect the status of a particular SSHChannel. Some requests will be automatically handled by the component. Others, however, may need the attention of the user to be dealt with properly within the scope of the application.

ConnectionId identifies the connection.

ChannelId identifies the channel receiving the request.

Type will contain the type of the request. These types depend on the type of the channel. For example, a "session" channel executing a command on the remote shell may receive an "exit-status" request containing the return code of that command.

RequestData contains the remainder of the original Secure Shell (SSH) packet. If the request type has specific parameters, they can be parsed out of this data.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHServiceRequest Event (SSHServer Component)

Fired when a client requests a service to be started.

Syntax

public event OnSSHServiceRequestHandler OnSSHServiceRequest;

public delegate void OnSSHServiceRequestHandler(object sender, SSHServerSSHServiceRequestEventArgs e);

public class SSHServerSSHServiceRequestEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string Service { get; }
  public bool Accept { get; set; }
}
Public Event OnSSHServiceRequest As OnSSHServiceRequestHandler

Public Delegate Sub OnSSHServiceRequestHandler(sender As Object, e As SSHServerSSHServiceRequestEventArgs)

Public Class SSHServerSSHServiceRequestEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property Service As String
  Public Property Accept As Boolean
End Class

Remarks

The SSHServiceRequest event is fired when a client requests that a service be started for a particular connection, identified by ConnectionId. Service will be the name of the service the client wishes to start. If the connection is authenticated and the user has access to the service, set Accept to True to allow the SSHServer to accept the request.

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHStatus Event (SSHServer Component)

Fired to show the progress of the secure connection.

Syntax

public event OnSSHStatusHandler OnSSHStatus;

public delegate void OnSSHStatusHandler(object sender, SSHServerSSHStatusEventArgs e);

public class SSHServerSSHStatusEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string Message { get; }
}
Public Event OnSSHStatus As OnSSHStatusHandler

Public Delegate Sub OnSSHStatusHandler(sender As Object, e As SSHServerSSHStatusEventArgs)

Public Class SSHServerSSHStatusEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property Message As String
End Class

Remarks

This event is fired for informational and logging purposes only. It is used to track the progress of the connection.

SSHTunnelClosed Event (SSHServer Component)

Fired when a connected client attempts to close a tunnel.

Syntax

public event OnSSHTunnelClosedHandler OnSSHTunnelClosed;

public delegate void OnSSHTunnelClosedHandler(object sender, SSHServerSSHTunnelClosedEventArgs e);

public class SSHServerSSHTunnelClosedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string Address { get; }
  public int Port { get; }
}
Public Event OnSSHTunnelClosed As OnSSHTunnelClosedHandler

Public Delegate Sub OnSSHTunnelClosedHandler(sender As Object, e As SSHServerSSHTunnelClosedEventArgs)

Public Class SSHServerSSHTunnelClosedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property Address As String
  Public ReadOnly Property Port As Integer
End Class

Remarks

This event fires when the connected client attempts to close a forward or reverse tunnel.

SSHTunnelRequested Event (SSHServer Component)

Fired when a connected client attempts to establish a forward or reverse tunnel.

Syntax

public event OnSSHTunnelRequestedHandler OnSSHTunnelRequested;

public delegate void OnSSHTunnelRequestedHandler(object sender, SSHServerSSHTunnelRequestedEventArgs e);

public class SSHServerSSHTunnelRequestedEventArgs : EventArgs {
  public string ConnectionId { get; }
  public int Direction { get; }
  public string Address { get; }
  public int Port { get; set; }
  public bool Accept { get; set; }
}
Public Event OnSSHTunnelRequested As OnSSHTunnelRequestedHandler

Public Delegate Sub OnSSHTunnelRequestedHandler(sender As Object, e As SSHServerSSHTunnelRequestedEventArgs)

Public Class SSHServerSSHTunnelRequestedEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property Direction As Integer
  Public ReadOnly Property Address As String
  Public Property Port As Integer
  Public Property Accept As Boolean
End Class

Remarks

This event fires when the connected client attempts to establish a forward or reverse tunnel. A forward tunnel, after being established, will forward all traffic from the client to a specified hostname and port. A reverse tunnel, after being established, will listen for incoming traffic on the same machine where SSHServer is running and any data received on that port will be forwarded to the client who requested the reverse tunnel.

SSHUserAuthRequest Event (SSHServer Component)

Fired when a client attempts to authenticate a connection.

Syntax

public event OnSSHUserAuthRequestHandler OnSSHUserAuthRequest;

public delegate void OnSSHUserAuthRequestHandler(object sender, SSHServerSSHUserAuthRequestEventArgs e);

public class SSHServerSSHUserAuthRequestEventArgs : EventArgs {
  public string ConnectionId { get; }
  public string User { get; }
  public string Service { get; }
  public string AuthMethod { get; }
  public string AuthParam { get; }
  public bool Accept { get; set; }
  public bool PartialSuccess { get; set; }
  public string AvailableMethods { get; set; }
  public string KeyAlgorithm { get; }
}
Public Event OnSSHUserAuthRequest As OnSSHUserAuthRequestHandler

Public Delegate Sub OnSSHUserAuthRequestHandler(sender As Object, e As SSHServerSSHUserAuthRequestEventArgs)

Public Class SSHServerSSHUserAuthRequestEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionId As String
  Public ReadOnly Property User As String
  Public ReadOnly Property Service As String
  Public ReadOnly Property AuthMethod As String
  Public ReadOnly Property AuthParam As String
  Public Property Accept As Boolean
  Public Property PartialSuccess As Boolean
  Public Property AvailableMethods As String
  Public ReadOnly Property KeyAlgorithm As String
End Class

Remarks

The SSHUserAuthRequest event fires when a Secure Shell (SSH) client attempts to authenticate itself on a particular connection. ConnectionId will identify the connection being authenticated. User will be the name of the account requesting authentication, and Service will contain the name of the service the client is wishing to access.

AuthMethod will denote which method the client is attempting to use to authenticate itself. AuthParam will contain the value of the authentication token used by the client. If the token is acceptable, you may set Accept to True to allow the component to authenticate the client. If it is not, set Accept to False.

Connecting clients will initially attempt authentication with an AuthMethod of "none". This is done with the expectation that the request will fail and the server will send a list of supported methods back to the client. In your implementation, check the AuthMethod parameter; if it is "none", you should set AvailableMethods and reject the request. The client will select one of the available methods and reauthenticate.

You may set AvailableMethods to a comma-delimited string of authentication methods that are available for the user. This list will be sent back to the client so that it may perform further authentication attempts.

The following is a list of methods implemented by the component:

noneThis authentication method is used by most Secure Shell (SSH) clients to obtain the list of authentication methods available for the user's account. In most cases, you should not accept a request using this authentication method.
passwordAuthParam will contain the user-supplied password. If the password is correct, set Accept to True.
publickeyAuthParam will contain an SSH2 public key blob. If the user's public key is acceptable, set Accept or PartialSuccess to true. The component will then handle verifying the digital signature and will respond to the client accordingly.
keyboard-interactiveSSHUserAuthRequest will fire multiple times for keyboard-interactive authentication: It will fire once for each response sent by the client in the SSH_MSG_USERAUTH_INFO_RESPONSE packet (one time for each prompt specified by the daemon). The index of each response will be specified as a suffix in AuthMethod, with AuthParam containing the response to the corresponding prompt (e.g., keyboard-interactive-1, keyboard-interactive-2, and so on). Finally, SSHUserAuthRequest will fire one last time with AuthMethod set to "keyboard-interactive" and AuthParam set to an empty string. The daemon must set Accept to True every time to allow the authentication process to succeed.

The PartialSuccess parameter is used only when multifactor authentication is needed. To implement multifactor authentication when this event fires, first verify the AuthParam for the given AuthMethod. If accepted, set PartialSuccess to True and Accept to False. The client should then send the authentication request for a different form of authentication specified in AvailableMethods. You may continue to set PartialSuccess to True until all authentication requirements are satisfied. Once all requirements are satisfied set Accept to True.

KeyAlgorithm holds the signing algorithm used when the client attempts public key authentication. Possible values are as follows:

  • ssh-rsa
  • rsa-sha2-256
  • rsa-sha2-512
  • ssh-dss
  • ecdsa-sha2-nistp256
  • ecdsa-sha2-nistp384
  • ecdsa-sha2-nistp521
  • x509v3-sign-rsa
  • x509v3-sign-dss

Note: Processing long-running requests, including sending channel data, inside this event may cause the underlying transport to stop processing Secure Shell (SSH) data until the event returns. To prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

The following fields are available:

Fields

EffectiveDate
string (read-only)

Default: ""

The date on which this certificate becomes valid. Before this date, it is not valid. The date is localized to the system's time zone. The following example illustrates the format of an encoded date:

23-Jan-2000 15:00:00.

ExpirationDate
string (read-only)

Default: ""

The date on which the certificate expires. After this date, the certificate will no longer be valid. The date is localized to the system's time zone. The following example illustrates the format of an encoded date:

23-Jan-2001 15:00:00.

ExtendedKeyUsage
string (read-only)

Default: ""

A comma-delimited list of extended key usage identifiers. These are the same as ASN.1 object identifiers (OIDs).

Fingerprint
string (read-only)

Default: ""

The hex-encoded, 16-byte MD5 fingerprint of the certificate. This property is primarily used for keys which do not have a corresponding X.509 public certificate, such as PEM keys that only contain a private key. It is commonly used for SSH keys.

The following example illustrates the format: bc:2a:72:af:fe:58:17:43:7a:5f:ba:5a:7c:90:f7:02

FingerprintSHA1
string (read-only)

Default: ""

The hex-encoded, 20-byte SHA-1 fingerprint of the certificate. This property is primarily used for keys which do not have a corresponding X.509 public certificate, such as PEM keys that only contain a private key. It is commonly used for SSH keys.

The following example illustrates the format: 30:7b:fa:38:65:83:ff:da:b4:4e:07:3f:17:b8:a4:ed:80:be:ff:84

FingerprintSHA256
string (read-only)

Default: ""

The hex-encoded, 32-byte SHA-256 fingerprint of the certificate. This property is primarily used for keys which do not have a corresponding X.509 public certificate, such as PEM keys that only contain a private key. It is commonly used for SSH keys.

The following example illustrates the format: 6a:80:5c:33:a9:43:ea:b0:96:12:8a:64:96:30:ef:4a:8a:96:86:ce:f4:c7:be:10:24:8e:2b:60:9e:f3:59:53

Issuer
string (read-only)

Default: ""

The issuer of the certificate. This field contains a string representation of the name of the issuing authority for the certificate.

PrivateKey
string (read-only)

Default: ""

The private key of the certificate (if available). The key is provided as PEM/Base64-encoded data.

Note: The PrivateKey may be available but not exportable. In this case, PrivateKey returns an empty string.

PrivateKeyAvailable
bool (read-only)

Default: False

Whether a PrivateKey is available for the selected certificate. If PrivateKeyAvailable is True, the certificate may be used for authentication purposes (e.g., server authentication).

PrivateKeyContainer
string (read-only)

Default: ""

The name of the PrivateKey container for the certificate (if available). This functionality is available only on Windows platforms.

PublicKey
string (read-only)

Default: ""

The public key of the certificate. The key is provided as PEM/Base64-encoded data.

PublicKeyAlgorithm
string (read-only)

Default: ""

The textual description of the certificate's public key algorithm. The property contains either the name of the algorithm (e.g., "RSA" or "RSA_DH") or an object identifier (OID) string representing the algorithm.

PublicKeyLength
int (read-only)

Default: 0

The length of the certificate's public key (in bits). Common values are 512, 1024, and 2048.

SerialNumber
string (read-only)

Default: ""

The serial number of the certificate encoded as a string. The number is encoded as a series of hexadecimal digits, with each pair representing a byte of the serial number.

SignatureAlgorithm
string (read-only)

Default: ""

The text description of the certificate's signature algorithm. The property contains either the name of the algorithm (e.g., "RSA" or "RSA_MD5RSA") or an object identifier (OID) string representing the algorithm.

Store
string

Default: "MY"

The name of the certificate store for the client certificate.

The StoreType field denotes the type of the certificate store specified by Store. If the store is password-protected, specify the password in StorePassword.

Store is used in conjunction with the Subject field to specify client certificates. If Store has a value, and Subject or Encoded is set, a search for a certificate is initiated. Please see the Subject field for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

MYA certificate store holding personal certificates with their associated private keys.
CACertifying authority certificates.
ROOTRoot certificates.

When the certificate store type is cstPFXFile, this property must be set to the name of the file. When the type is cstPFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

StoreB
byte []

Default: "MY"

The name of the certificate store for the client certificate.

The StoreType field denotes the type of the certificate store specified by Store. If the store is password-protected, specify the password in StorePassword.

Store is used in conjunction with the Subject field to specify client certificates. If Store has a value, and Subject or Encoded is set, a search for a certificate is initiated. Please see the Subject field for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

MYA certificate store holding personal certificates with their associated private keys.
CACertifying authority certificates.
ROOTRoot certificates.

When the certificate store type is cstPFXFile, this property must be set to the name of the file. When the type is cstPFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

StorePassword
string

Default: ""

If the type of certificate store requires a password, this field is used to specify the password needed to open the certificate store.

StoreType
CertStoreTypes

Default: 0

The type of certificate store for this certificate.

The component supports both public and private keys in a variety of formats. When the cstAuto value is used, the component will automatically determine the type. This field can take one of the following values:

0 (cstUser - default)For Windows, this specifies that the certificate store is a certificate store owned by the current user.

Note: This store type is not available in Java.

1 (cstMachine)For Windows, this specifies that the certificate store is a machine store.

Note: This store type is not available in Java.

2 (cstPFXFile)The certificate store is the name of a PFX (PKCS#12) file containing certificates.
3 (cstPFXBlob)The certificate store is a string (binary or Base64-encoded) representing a certificate store in PFX (PKCS#12) format.
4 (cstJKSFile)The certificate store is the name of a Java Key Store (JKS) file containing certificates.

Note: This store type is only available in Java.

5 (cstJKSBlob)The certificate store is a string (binary or Base64-encoded) representing a certificate store in Java Key Store (JKS) format.

Note: This store type is only available in Java.

6 (cstPEMKeyFile)The certificate store is the name of a PEM-encoded file that contains a private key and an optional certificate.
7 (cstPEMKeyBlob)The certificate store is a string (binary or Base64-encoded) that contains a private key and an optional certificate.
8 (cstPublicKeyFile)The certificate store is the name of a file that contains a PEM- or DER-encoded public key certificate.
9 (cstPublicKeyBlob)The certificate store is a string (binary or Base64-encoded) that contains a PEM- or DER-encoded public key certificate.
10 (cstSSHPublicKeyBlob)The certificate store is a string (binary or Base64-encoded) that contains an SSH-style public key.
11 (cstP7BFile)The certificate store is the name of a PKCS#7 file containing certificates.
12 (cstP7BBlob)The certificate store is a string (binary) representing a certificate store in PKCS#7 format.
13 (cstSSHPublicKeyFile)The certificate store is the name of a file that contains an SSH-style public key.
14 (cstPPKFile)The certificate store is the name of a file that contains a PPK (PuTTY Private Key).
15 (cstPPKBlob)The certificate store is a string (binary) that contains a PPK (PuTTY Private Key).
16 (cstXMLFile)The certificate store is the name of a file that contains a certificate in XML format.
17 (cstXMLBlob)The certificate store is a string that contains a certificate in XML format.
18 (cstJWKFile)The certificate store is the name of a file that contains a JWK (JSON Web Key).
19 (cstJWKBlob)The certificate store is a string that contains a JWK (JSON Web Key).
21 (cstBCFKSFile)The certificate store is the name of a file that contains a BCFKS (Bouncy Castle FIPS Key Store).

Note: This store type is only available in Java and .NET.

22 (cstBCFKSBlob)The certificate store is a string (binary or Base64-encoded) representing a certificate store in BCFKS (Bouncy Castle FIPS Key Store) format.

Note: This store type is only available in Java and .NET.

23 (cstPKCS11)The certificate is present on a physical security key accessible via a PKCS#11 interface.

To use a security key, the necessary data must first be collected using the CertMgr component. The ListStoreCertificates method may be called after setting CertStoreType to cstPKCS11, CertStorePassword to the PIN, and CertStore to the full path of the PKCS#11 DLL. The certificate information returned in the CertList event's CertEncoded parameter may be saved for later use.

When using a certificate, pass the previously saved security key information as the Store and set StorePassword to the PIN.

Code Example. SSH Authentication with Security Key: certmgr.CertStoreType = CertStoreTypes.cstPKCS11; certmgr.OnCertList += (s, e) => { secKeyBlob = e.CertEncoded; }; certmgr.CertStore = @"C:\Program Files\OpenSC Project\OpenSC\pkcs11\opensc-pkcs11.dll"; certmgr.CertStorePassword = "123456"; //PIN certmgr.ListStoreCertificates(); sftp.SSHCert = new Certificate(CertStoreTypes.cstPKCS11, secKeyBlob, "123456", "*"); sftp.SSHUser = "test"; sftp.SSHLogon("myhost", 22);

99 (cstAuto)The store type is automatically detected from the input data. This setting may be used with both public and private keys and can detect any of the supported formats automatically.

SubjectAltNames
string (read-only)

Default: ""

Comma-separated lists of alternative subject names for the certificate.

ThumbprintMD5
string (read-only)

Default: ""

The MD5 hash of the certificate. It is primarily used for X.509 certificates. If the hash does not already exist, it is automatically computed.

ThumbprintSHA1
string (read-only)

Default: ""

The SHA-1 hash of the certificate. It is primarily used for X.509 certificates. If the hash does not already exist, it is automatically computed.

ThumbprintSHA256
string (read-only)

Default: ""

The SHA-256 hash of the certificate. It is primarily used for X.509 certificates. If the hash does not already exist, it is automatically computed.

Usage
string (read-only)

Default: ""

The text description of UsageFlags.

This value will be one or more of the following strings and will be separated by commas:

  • Digital Signature
  • Non-Repudiation
  • Key Encipherment
  • Data Encipherment
  • Key Agreement
  • Certificate Signing
  • CRL Signing
  • Encipher Only

If the provider is OpenSSL, the value is a comma-separated list of X.509 certificate extension names.

UsageFlags
int (read-only)

Default: 0

The flags that show intended use for the certificate. The value of UsageFlags is a combination of the following flags:

0x80Digital Signature
0x40Non-Repudiation
0x20Key Encipherment
0x10Data Encipherment
0x08Key Agreement
0x04Certificate Signing
0x02CRL Signing
0x01Encipher Only

Please see the Usage field for a text representation of UsageFlags.

This functionality currently is not available when the provider is OpenSSL.

Version
string (read-only)

Default: ""

The certificate's version number. The possible values are the strings "V1", "V2", and "V3".

Subject
string

Default: ""

The subject of the certificate used for client authentication.

This field will be populated with the full subject of the loaded certificate. When loading a certificate, the subject is used to locate the certificate in the store.

If an exact match is not found, the store is searched for subjects containing the value of the property.

If a match is still not found, the property is set to an empty string, and no certificate is selected.

The special value "*" picks a random certificate in the certificate store.

The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:

FieldMeaning
CNCommon Name. This is commonly a hostname like www.server.com.
OOrganization
OUOrganizational Unit
LLocality
SState
CCountry
EEmail Address

If a field value contains a comma, it must be quoted.

Encoded
string

Default: ""

The certificate (PEM/Base64 encoded). This field is used to assign a specific certificate. The Store and Subject fields also may be used to specify a certificate.

When Encoded is set, a search is initiated in the current Store for the private key of the certificate. If the key is found, Subject is updated to reflect the full subject of the selected certificate; otherwise, Subject is set to an empty string.

EncodedB
byte []

Default: ""

The certificate (PEM/Base64 encoded). This field is used to assign a specific certificate. The Store and Subject fields also may be used to specify a certificate.

When Encoded is set, a search is initiated in the current Store for the private key of the certificate. If the key is found, Subject is updated to reflect the full subject of the selected certificate; otherwise, Subject is set to an empty string.

Constructors

public Certificate();
Public Certificate()

Creates a instance whose properties can be set. This is useful for use with when generating new certificates.

public Certificate(string certificateFile);
Public Certificate(ByVal CertificateFile As String)

Opens CertificateFile and reads out the contents as an X.509 public key.

public Certificate(byte[] encoded);
Public Certificate(ByVal Encoded As Byte())

Parses Encoded as an X.509 public key.

public Certificate(CertStoreTypes storeType, string store, string storePassword, string subject);
Public Certificate(ByVal StoreType As CertStoreTypes, ByVal Store As String, ByVal StorePassword As String, ByVal Subject As String)

StoreType identifies the type of certificate store to use. See for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store.

After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X.509 certificate's subject Distinguished Name (DN). The Subject parameter can also take an MD5, SHA-1, or SHA-256 thumbprint of the certificate to load in a "Thumbprint=value" format.

public Certificate(CertStoreTypes storeType, string store, string storePassword, string subject, string configurationString);
Public Certificate(ByVal StoreType As CertStoreTypes, ByVal Store As String, ByVal StorePassword As String, ByVal Subject As String, ByVal ConfigurationString As String)

StoreType identifies the type of certificate store to use. See for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store.

ConfigurationString is a newline-separated list of name-value pairs that may be used to modify the default behavior. Possible values include "PersistPFXKey", which shows whether or not the PFX key is persisted after performing operations with the private key. This correlates to the PKCS12_NO_PERSIST_KEY CryptoAPI option. The default value is True (the key is persisted). "Thumbprint" - an MD5, SHA-1, or SHA-256 thumbprint of the certificate to load. When specified, this value is used to select the certificate in the store. This is applicable to the cstUser , cstMachine , cstPublicKeyFile , and cstPFXFile store types. "UseInternalSecurityAPI" shows whether the platform (default) or the internal security API is used when performing certificate-related operations.

After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X.509 certificate's subject Distinguished Name (DN). The Subject parameter can also take an MD5, SHA-1, or SHA-256 thumbprint of the certificate to load in a "Thumbprint=value" format.

public Certificate(CertStoreTypes storeType, string store, string storePassword, byte[] encoded);
Public Certificate(ByVal StoreType As CertStoreTypes, ByVal Store As String, ByVal StorePassword As String, ByVal Encoded As Byte())

StoreType identifies the type of certificate store to use. See for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store.

After the store has been successfully opened, the component will load Encoded as an X.509 certificate and search the opened store for a corresponding private key.

public Certificate(CertStoreTypes storeType, byte[] store, string storePassword, string subject);
Public Certificate(ByVal StoreType As CertStoreTypes, ByVal Store As Byte(), ByVal StorePassword As String, ByVal Subject As String)

StoreType identifies the type of certificate store to use. See for descriptions of the different certificate stores. Store is a byte array containing the certificate data. StorePassword is the password used to protect the store.

After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X.509 certificate's subject Distinguished Name (DN). The Subject parameter can also take an MD5, SHA-1, or SHA-256 thumbprint of the certificate to load in a "Thumbprint=value" format.

public Certificate(CertStoreTypes storeType, byte[] store, string storePassword, string subject, string configurationString);
Public Certificate(ByVal StoreType As CertStoreTypes, ByVal Store As Byte(), ByVal StorePassword As String, ByVal Subject As String, ByVal ConfigurationString As String)

StoreType identifies the type of certificate store to use. See for descriptions of the different certificate stores. Store is a byte array containing the certificate data. StorePassword is the password used to protect the store.

After the store has been successfully opened, the component will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X.509 certificate's subject Distinguished Name (DN). The Subject parameter can also take an MD5, SHA-1, or SHA-256 thumbprint of the certificate to load in a "Thumbprint=value" format.

public Certificate(CertStoreTypes storeType, byte[] store, string storePassword, byte[] encoded);
Public Certificate(ByVal StoreType As CertStoreTypes, ByVal Store As Byte(), ByVal StorePassword As String, ByVal Encoded As Byte())

StoreType identifies the type of certificate store to use. See for descriptions of the different certificate stores. Store is a byte array containing the certificate data. StorePassword is the password used to protect the store.

After the store has been successfully opened, the component will load Encoded as an X.509 certificate and search the opened store for a corresponding private key.

SSHChannel Type

Describes a currently open Secure Shell (SSH) channel.

Remarks

This type describes the Secure Shell (SSH) client's currently open channels. You may use the different fields for this type to manage the channel.

The following fields are available:

Fields

BytesSent
int (read-only)

Default: 0

This field specifies the number of bytes actually sent after a sending channel data.

ChannelEOL
string

Default: ""

Breaks the incoming data stream into chunks separated by EOL.

This property is a binary string. Notably, this means that it can be more than one byte long, and it can contain NULL bytes.

ChannelEOL and MaxChannelLength must be set together or unexpected behavior could occur.

ChannelId
string (read-only)

Default: ""

This field provides an Id generated by the component to identify the current Secure Shell (SSH) channel.

This Id is unique to this channel.

MaxChannelLength
int

Default: 0

This field specifies the maximum amount of data to accumulate when no EOL is found.

MaxChannelLength is the size of an internal buffer, which holds received data while waiting for a ChannelEOL string.

If the ChannelEOL string is found in the input stream before MaxChannelLength bytes are received, the SSHChannelData event is fired with the ChannelDataEOLFound parameter set to True, and the buffer is reset.

If no ChannelEOL is found, and MaxChannelLength bytes are accumulated in the buffer, the SSHChannelData event is fired with the ChannelDataEOLFound parameter set to False, and the buffer is reset.

ChannelEOL and MaxChannelLength must be set together or unexpected behavior could occur.

ReadyToSend
bool (read-only)

Default: False

This field is True when data can be sent over the Secure Shell (SSH) channel.

When Timeout is set to 0 (asynchronous) sending data may result in an error if the channel or underlying socket cannot accept more data to send. Monitor SSHChannelReadyToSend or ReadyToSend to determine when data can be sent again.

When Timeout is set to a positive value, the component will block when sending data until the data can be successfully sent and SSHChannelReadyToSend and ReadyToSend do not need to be monitored.

RecordLength
int (read-only)

Default: 0

This field holds the current record length set by ChangeRecordLength. When this value is a positive number, the component will accumulate data until RecordLength is reached and only then will it fire the SSHChannelDataIn event with the data of length RecordLength. This allows data to be received as records of known length. This value can be changed at any time by calling ChangeRecordLength, including within the SSHChannelDataIn event.

A value of 0 (default) means this setting is not used.

Service
string (read-only)

Default: ""

This field holds the channel type that was requested when opening the channel. For instance "session" or "forwarded-tcpip".

SSHConnection Type

A currently connected client.

Remarks

This type describes the connection of a client that is currently connected to the component. You may use the different fields of this type to manage the connection.

The following fields are available:

Fields

Connected
bool (read-only)

Default: False

This field indicates the status of individual connections.

When true, the connection is established. Use the Disconnect method to disconnect an existing connection.

ConnectionId
string (read-only)

Default: ""

This field contains an Id generated by the component to identify each connection. This Id is unique to this connection.

LocalAddress
string (read-only)

Default: ""

This field shows the IP address of the interface through which the connection is passing.

LocalAddress is important for multihomed hosts in cases in which it can be used to identify the particular network interface an individual connection is going through.

RemoteHost
string (read-only)

Default: ""

The RemoteHost shows the IP address of the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

If the component is configured to use a SOCKS firewall, the value assigned to this property may be preceded with an "*". If this is the case, the host name is passed to the firewall unresolved and the firewall performs the DNS resolution.

RemotePort
int (read-only)

Default: 0

The RemotePort shows the Transmission Control Protocol (TCP) port on the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

Timeout
int

Default: 0

This field contains a timeout for the component.

If the Timeout field is set to 0, all operations will run uninterrupted until successful completion or an error condition is encountered.

If Timeout is set to a positive value, the component will wait for the operation to complete before returning control.

The component will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not freeze and remains responsive.

If Timeout expires, and the operation is not yet complete, the component throws an exception.

Note: By default, all timeouts are inactivity timeouts, that is, the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for Timeout is specified by the DefaultTimeout property.

Constructors

public SSHConnection();
Public SSHConnection()

SSHPrompt Type

A prompt to provide to the client during keyboard-interactive authentication.

Remarks

This type describes a prompt the Secure Shell (SSH) daemon will send to the client when requesting keyboard-interactive authentication.

The following fields are available:

Fields

Echo
bool

Default: False

This field specifies whether or not the client should echo the value entered by the user.

Prompt
string

Default: ""

This field contains the prompt label or text the client should present to the user.

Constructors

public SSHPrompt();
Public SSHPrompt()
public SSHPrompt(string prompt, bool echo);
Public SSHPrompt(ByVal Prompt As String, ByVal Echo As Boolean)

Config Settings (SSHServer Component)

The component accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

SSHServer Config Settings

AltSSHCertCount:   The number of records in the AltSSHCert configuration settings.

This configuration setting controls the size of the following arrays:

The array indices start at 0 and end at AltSSHCertCount - 1.

The AltSSHCert configuration settings are used to specify alternative digital certificates to the one set using the SSHCert. The server will determine the certificate to use during Secure Shell (SSH) negotiation based on the public key algorithm requested by the connecting client. A certificate with a private key is required for session authentication and encryption. The AltSSHCertSubject setting must be set last. When AltSSHCertSubject is set, a search is initiated in the AltSSHCertStore and the certificate is loaded.

The alternative server certificate specified by these settings must be configured before setting Listening to true. For example: sftpserver.Config("AltSSHCertCount =1"); sftpserver.Config("AltSSHCertStoreType[0]=7"); //PEM Key Blob sftpserver.Config("AltSSHCertStore[0]=" + ed25519Key); //PEM formatted string sftpserver.Config("AltSSHCertSubject[0]=*"); //Load the first (and only) certificate

AltSSHCertStore[i]:   The name of the certificate store.

The name of the certificate store. This configuration setting is used when specifying an alternative SSHCert.

The AltSSHCertStoreType specifies the type of the certificate store specified by AltSSHCertStore. If the store is password protected, specify the password in the AltSSHCertStorePassword.

AltSSHCertStore is used in conjunction with the AltSSHCertSubject field to specify the certificate.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

MYA certificate store holding personal certificates with their associated private keys.
CACertifying authority certificates.
ROOTRoot certificates.

When the certificate store type is cstPFXFile, this property must be set to the name of the file. When the type is cstPFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

AltSSHCertStorePassword[i]:   The password used to open the certificate store.

If the certificate store requires a password, this configuration setting can be used to specify that password. This setting is used when specifying an alternative SSHCert

AltSSHCertStoreType[i]:   The type of certificate store.

This configuration setting specifies the type of certificate store. This setting is used when specifying an alternate SSHCert. Possible values are as follows:

0 User - This is the default for Windows. This specifies that the certificate store is a certificate store owned by the current user. Note: This store type is not available in Java.
1 Machine - For Windows, this specifies that the certificate store is a machine store. Note: This store type is not available in Java.
2 PFXFile - The certificate store is the name of a PFX (PKCS12) file containing certificates.
3 PFXBlob - The certificate store is a string (binary or Base64-encoded) representing a certificate store in PFX (PKCS12) format.
4 JKSFile - The certificate store is the name of a Java Key Store (JKS) file containing certificates. Note: This store type is available only in Java.
5 JKSBlob - The certificate store is a string (binary or Base64-encoded) representing a certificate store in Java Key Store (JKS) format. Note: This store type is available only in Java.
6 PEMKeyFile - The certificate store is the name of a PEM-encoded file that contains a private key and an optional certificate.
7 PEMKeyBlob - The certificate store is a string (binary or Base64-encoded) that contains a private key and an optional certificate.
14 PPKFile - The certificate store is the name of a file that contains a PPK (PuTTY Private Key).
15 PPKBlob - The certificate store is a string (binary) that contains a PPK (PuTTY Private Key).
16 XMLFile - The certificate store is the name of a file that contains a certificate in XML format.
17 XMLBlob - The certificate store is a string that contains a certificate in XML format.
AltSSHCertSubject[i]:   The alternative certificate subject.

The subject of the certificate. This configuration setting is used when specifying an alternative SSHCert. The special value of * may be used to select the first certificate in the store.

ClientSSHVersionString[ConnectionId]:   The client's version string.

This configuration setting returns a connected client's SSH version string. It may be queried inside SSHUserAuthRequest. sftpserver1.OnSSHUserAuthRequest += (obj, ev) => { Console.WriteLine(sftpserver1.Config("ClientSSHVersionString[" + ev.ConnectionId + "]")); };

FireAuthRequestAfterSig:   Whether to fire an informational event after the public key signature has been verified.

When performing public key authentication, the connecting client will present both the public key as well as a signature to verify ownership of the corresponding private key. The component will automatically verify the signature and respond to the client to indicate whether the signature could be verified and the connection can continue. This configuration setting controls whether an additional informational event fires to report the result of the signature verification.

If set to true, the SSHUserAuthRequest event will fire twice per public key authentication attempt. The first time the event fires for public key authentication as usual. After verification of the signature has taken place, the SSHUserAuthRequest will fire again, and the AuthMethod parameter will contain the string sigstatus. The AuthParam parameter will contain a value of 0 (invalid signature) or 1 (valid signature). If the signature is invalid, it will always result in a rejected authentication attempt.

KeyboardInteractivePrompts[ConnectionId]:   Specifies custom keyboard-interactive prompts for particular connections.

By default, setting the KeyboardInteractivePrompts property will cause those prompts to be used for every user attempting to connect. This setting can be used to override the KeyboardInteractivePrompts property and provide unique prompts for certain connections.

This configuration setting takes a list of prompts to display to the client, and each prompt includes an 'echo' parameter to specify whether or not to echo the client's response to the prompt. The prompt and the echo parameter should be separated by a comma (","), and each prompt should be separated by a semicolon (";"). For example:

"KeyboardInteractivePrompts[connId]=First prompt,echo=false;Second prompt,echo=true"

This configuration setting can be set anywhere in code, but it is necessary to know the ConnectionId for the specific connection beforehand; as such, it is generally recommended to set this configuration inside the SSHUserAuthRequest event. Because connecting clients initially attempt to connect with and AuthMethod of 'none' (with the understanding that this attempt will fail, and the SSH server will advertise which authentication methods it supports), it is recommended to check the AuthMethod, User, and ConnectionId parameters of the SSHUserAuthRequest event and set this configuration setting accordingly.

When SSHServer displays keyboard-interactive prompts, it will first check to see if this configuration setting is populated for the current ConnectionId. If it is, the prompts set here will be used instead of those set in the KeyboardInteractivePrompts property. Otherwise, the KeyboardInteractivePrompts property will function as normal.

KeyRenegotiationThreshold:   Sets the threshold for the SSH Key Renegotiation.

This property allows you to specify the threshold, in the number of bytes, for the Secure Shell (SSH) key renegotiation. The default value for this property is set to 1 GB.

Example. Setting the Threshold to 500 MB: SSHComponent.Config("KeyRenegotiationThreshold=524288000")

LogLevel:   Specifies the level of detail that is logged.

This configuration setting controls the level of detail that is logged through the Log event. Possible values are as follows:

0 (None) No messages are logged.
1 (Info - Default) Informational events such as Secure Shell (SSH) handshake messages are logged.
2 (Verbose) Detailed data such as individual packet information are logged.
3 (Debug) Debug data including all relevant sent and received bytes are logged.

MaxAuthAttempts:   The maximum authentication attempts allowed before forcing a disconnect.

This configuration setting specifies the maximum amount of authentication attempts that will be allowed before forcibly disconnecting the client.

NegotiatedStrictKex[ConnectionId]:   Returns whether strict key exchange was negotiated to be used.

Returns whether strict key exchange (strict kex) was negotiated during the SSH handshake. This is a per-connection configuration setting accessed by passing the ConnectionId. If strict kex is being used, then this will return "True". If strict kex is not being used, then this will return "False".

component.Config("NegotiatedStrictKex[connId]")

ServerSSHVersionString:   The SSH version string sent to connecting clients.

This configuration setting specifies the version string value that is sent to all connecting clients. This may be set to specify server specific information. The default value is "SSH-2.0-IPWorks SSH Daemon 2024". When setting your own value, it must begin with "SSH-2.0-" because this is a standard format that specifies the supported SSH version.

SSHKeepAliveCountMax:   The maximum number of keep alive packets to send without a response.

This configuration setting specifies the maximum number of keep-alive packets to send when no response is received. Normally a response to a keep-alive packet is received right away. If no response is received, the component will continue to send keep-alive packets until SSHKeepAliveCountMax is reached. If this is reached, the component will assume the connection is broken and disconnect. The default value is 5.

SSHKeepAliveInterval:   The interval between keep alive packets.

This configuration setting specifies the number of seconds between keep-alive packets. If set to a positive value, the component will send a SSH keep-alive packet after KeepAliveInterval seconds of inactivity. This configuration setting takes effect only when there is no activity. If any data are sent or received over the connection, it will reset the timer.

The default value is 0, meaning no keep alives will be sent.

Note: The SSHReverseTunnel component uses a default value of 30.

SSHKeyExchangeAlgorithms:   Specifies the supported key exchange algorithms.

This configuration setting may be used to specify the list of supported key exchange algorithms used during Secure Shell (SSH) negotiation. The value should contain a comma-separated list of algorithms. Supported algorithms are as follows:

  • curve25519-sha256
  • curve25519-sha256@libssh.org
  • diffie-hellman-group1-sha1
  • diffie-hellman-group14-sha1
  • diffie-hellman-group14-sha256
  • diffie-hellman-group16-sha512
  • diffie-hellman-group18-sha512
  • diffie-hellman-group-exchange-sha256
  • diffie-hellman-group-exchange-sha1
  • ecdh-sha2-nistp256
  • ecdh-sha2-nistp384
  • ecdh-sha2-nistp521
  • gss-group14-sha256-toWM5Slw5Ew8Mqkay+al2g==
  • gss-group16-sha512-toWM5Slw5Ew8Mqkay+al2g==
  • gss-nistp256-sha256-toWM5Slw5Ew8Mqkay+al2g==
  • gss-curve25519-sha256-toWM5Slw5Ew8Mqkay+al2g==
  • gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==
  • gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==
The default value is curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1,gss-group14-sha256-toWM5Slw5Ew8Mqkay+al2g==,gss-group16-sha512-toWM5Slw5Ew8Mqkay+al2g==,gss-nistp256-sha256-toWM5Slw5Ew8Mqkay+al2g==,gss-curve25519-sha256-toWM5Slw5Ew8Mqkay+al2g==,gss-group14-sha1-toWM5Slw5Ew8Mqkay+al2g==,gss-gex-sha1-toWM5Slw5Ew8Mqkay+al2g==.
SSHMacAlgorithms:   Specifies the supported Mac algorithms.

This configuration setting may be used to specify an alternate list of supported Mac algorithms used during SSH negotiation. This also specifies the order in which the Mac algorithms are preferred. The value should contain a comma-separated list of algorithms. Supported algorithms are as follows:

  • hmac-sha1
  • hmac-md5
  • hmac-sha1-96
  • hmac-md5-96
  • hmac-sha2-256
  • hmac-sha2-256-96
  • hmac-sha2-512
  • hmac-sha2-512-96
  • hmac-ripemd160
  • hmac-ripemd160-96
  • hmac-sha2-256-etm@openssh.com
  • hmac-sha2-512-etm@openssh.com
  • hmac-sha2-256-96-etm@openssh.com
  • hmac-sha2-512-96-etm@openssh.com
  • umac-64@openssh.com
  • umac-64-etm@openssh.com
  • umac-128@openssh.com
  • umac-128-etm@openssh.com
The default value is hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-md5,hmac-ripemd160,hmac-sha1-96,hmac-md5-96,hmac-sha2-256-96,hmac-sha2-512-96,hmac-ripemd160-96,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,umac-64@openssh.com,umac-64-etm@openssh.com,umac-128@openssh.com,umac-128-etm@openssh.com.
SSHPubKeyAuthSigAlgorithms:   Specifies the allowed signature algorithms used by a client performing public key authentication.

This configuration setting specifies a list of signature algorithms that a client is allowed to use when authenticating to the server using public key authentication. This applies only when public key authentication is performed by the client.

The configuration setting should be a comma-separated list of algorithms. When a client connects, the server will verify that the client performing the public key authentication has used one of the specified signature algorithms. If the client uses a signature algorithm that is not in the list, the connection will be rejected.

Possible values areas follows:

  • ssh-rsa
  • rsa-sha2-256
  • rsa-sha2-512
  • ssh-dss
  • ecdsa-sha2-nistp256
  • ecdsa-sha2-nistp384
  • ecdsa-sha2-nistp521
  • ssh-ed25519
  • x509v3-sign-rsa
  • x509v3-sign-dss

The default value in Windows is ssh-rsa,rsa-sha2-256,rsa-sha2-512,x509v3-sign-rsa,ssh-dss,x509v3-sign-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519.

SSHPublicKeyAlgorithms:   Specifies the supported public key algorithms for the server's public key.

This configuration setting specifies the allowed public key algorithms for the server's public key. This list controls only the public key algorithm used when authenticating the server's public key. This list has no bearing on the public key algorithms that can be used by the client when performing public key authentication to the server. The default value is ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,rsa-sha2-256,rsa-sha2-512,ssh-rsa,ssh-dss,x509v3-sign-rsa,x509v3-sign-dss.

SSHVersionPattern:   The pattern used to match the remote host's version string.

This configuration setting specifies the pattern used to accept or deny the remote host's SSH version string. It takes a comma-delimited list of patterns to match. The default value is "*SSH-1.99-*,*SSH-2.0-*" and will accept connections from SSH 1.99 and 2.0 hosts. As an example, the following value would accept connections for SSH 1.99, 2.0, and 2.99 hosts:

*SSH-1.99-*,*SSH-2.0-*,*SSH-2.99-*
UserAuthBanner[ConnectionId]:   A custom user authentication banner.

This configuration setting specifies a custom user authentication banner, which may be sent to give the client more information regarding an authentication attempt. "ConnectionId" specifies the particular connection to send the message to. This configuration option is effective only when set within the SSHUserAuthRequest event.

UseStrictKeyExchange:   Specifies how strict key exchange is supported.

This configuration setting controls whether strict key exchange (strict kex) is enabled to mitigate the Terrapin attack. When enabled, the component will indicate support for strict key exchange by automatically including the pseudo-algorithm kex-strict-c-v00@openssh.com for client components and kex-strict-s-v00@openssh.com for server components in the list of supported key exchange algorithms.

Because both client and server must implement strict key exchange to effectively mitigate the Terrapin attack, the component provides options to further control the behavior in different scenarios. Possible values for this setting are as follows:

0Disabled. Strict key exchange is not supported in the component.
1 (default)Enabled, but not enforced. This setting enables strict key exchange, but if the remote host does not support strict key exchange the connection is still allowed to continue.
2Enabled, but will reject affected algorithms if the remote host does not support strict key exchange. If the remote host supports strict key exchange, all algorithms may be used. If the remote host does not support strict key exchange, the connection will continue only if the selected encryption and message authentication code (MAC) algorithms are not affected by the Terrapin attack.
3Required. If the remote host does not support strict key exchange, the connection will fail.

TCPServer Config Settings

AllowedClients:   A comma-separated list of host names or IP addresses that can access the component.

This configuration setting defines a comma-separated list of host names or IPv4 addresses that may access the component. The wildcard character "*" is supported. The default value is "*" and all connections are accepted.

When a client connects, the client's address is checked against the list defined here. If there is no match, the ConnectionRequest event fires with an Accept value set to false. If no action is taken within the ConnectionRequest event, the client will be disconnected.

BindExclusively:   Whether or not the component considers a local port reserved for exclusive use.

If this is true (default), the component will bind to the local port with the ExclusiveAddressUse option set, meaning that nothing else can bind to the same port. Also the component will not be able to bind to local ports that are already in use by some other instance, and attempts to do so will result in failure.

BlockedClients:   A comma-separated list of host names or IP addresses that cannot access the component.

This configuration setting defines a comma-separated list of host names or IPv4 addresses that cannot access the component.The default value is "" and all connections are accepted.

When a client connects, the client's address is checked against the list defined here. If there is a match, the ConnectionRequest event fires with an Accept value set to false. If no action is taken within the ConnectionRequest event, the client will not be connected.

CloseStreamAfterTransfer:   If true, the component will close the upload or download stream after the transfer.

This configuration setting determines whether the input or output stream is closed after the transfer completes. When set to True (default), all streams will be closed after a transfer is completed. To keep streams open after the transfer of data, set this to False. The default value is True.

DefaultConnectionTimeout:   The inactivity timeout applied to the SSL handshake.

This configuration setting specifies the inactivity (in seconds) to apply to incoming Secure Sockets Layer (SSL) connections. When set to a positive value, if the other end is unresponsive for the specified number of seconds, the connection will timeout. This is not applicable to the entire handshake. It is applicable only to the inactivity of the connecting client during the handshake if a response is expected and none is received within the timeout window. The default value is 0, and no connection-specific timeout is applied.

Note: This is applicable only to incoming SSL connections. This should be set only if there is a specific reason to do so.

InBufferSize:   The size in bytes of the incoming queue of the socket.

This is the size of an internal queue in the Transmission Control Protocol (TCP)/IP stack. You can increase or decrease its size depending on the amount of data that you will be receiving. Increasing the value of the InBufferSize setting can provide significant improvements in performance in some cases.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the component is activated, the InBufferSize reverts to its defined size. The same thing will happen if you attempt to make it too large or too small.

InBufferSize is shared among incoming connections. When the property is set, the corresponding value is set for incoming connections as they are accepted. Existing connections are not modified.

KeepAliveInterval:   The retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.

A TCP keep-alive packet will be sent after a period of inactivity, as defined by KeepAliveTime. If no acknowledgment is received from the remote host, the keep-alive packet will be sent again. This setting specifies the interval at which the successive keep-alive packets are sent in milliseconds. If this value is not specified here, the system default is 1 second. This setting is applicable to all connections.

Note: This value is not applicable in macOS.

KeepAliveTime:   The inactivity time in milliseconds before a TCP keep-alive packet is sent.

By default, the operating system will determine the time a connection is idle before a TCP keep-alive packet is sent. If this value is not specified here, the system default is 2 hours. In many cases, a shorter interval is more useful. Set this value to the desired interval in milliseconds. This setting is applicable to all connections.

MaxConnections:   The maximum number of connections available.

This is the maximum number of connections available. This property must be set before Listening is set to true, and once set, it can no longer be changed for the current instance of the component. The maximum value for this setting is 100,000 connections. Use this setting with caution. Extremely large values may affect performance.

OutBufferSize:   The size in bytes of the outgoing queue of the socket.

This is the size of an internal queue in the TCP/IP stack. You can increase or decrease its size depending on the amount of data that you will be sending. Increasing the value of the OutBufferSize setting can provide significant improvements in performance in some cases.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the component is activated the OutBufferSize reverts to its defined size. The same thing will happen if you attempt to make it too large or too small.

OutBufferSize is shared among incoming connections. When the property is set, the corresponding value is set for incoming connections as they are accepted. Existing connections are not modified.

PreferredDHGroupBits:   Size of the Diffie-Hellman group, in bits.

This configuration setting specifies the key length used by the Diffe-Hellman key algorithm. The default value is 2048 (bits).

TcpNoDelay:   Whether or not to delay when sending packets.

When set to True, the socket will send all data that are ready to send at once. When set to False, the socket will send smaller buffered packets of data at small intervals. This is known as the Nagle algorithm.

By default, this configuration setting is set to False.

UseBackgroundThread:   Whether threads created by the component are background threads.

If set to true, when the component creates a thread, the thread's IsBackground property will be explicitly set to true. By default, this setting is false.

UseIPv6:   Whether to use IPv6.

When set to 0 (default), the component will use IPv4 exclusively. When set to 1, the component will use IPv6 exclusively. When set to 2, the component will listen for both IPv4 and IPv6 connections. If IPv6 is not available on the system, only IPv4 will be used. The default value is 0. Possible values are as follows:

0 IPv4 Only
1 IPv6 Only
2 IPv6 and IPv4

Base Config Settings

BuildInfo:   Information about the product's build.

When queried, this setting will return a string containing information about the product's build.

GUIAvailable:   Whether or not a message loop is available for processing events.

In a GUI-based application, long-running blocking operations may cause the application to stop responding to input until the operation returns. The component will attempt to discover whether or not the application has a message loop and, if one is discovered, it will process events in that message loop during any such blocking operation.

In some non-GUI applications, an invalid message loop may be discovered that will result in errant behavior. In these cases, setting GUIAvailable to false will ensure that the component does not attempt to process external events.

LicenseInfo:   Information about the current license.

When queried, this setting will return a string containing information about the license this instance of a component is using. It will return the following information:

  • Product: The product the license is for.
  • Product Key: The key the license was generated from.
  • License Source: Where the license was found (e.g., RuntimeLicense, License File).
  • License Type: The type of license installed (e.g., Royalty Free, Single Server).
  • Last Valid Build: The last valid build number for which the license will work.
MaskSensitiveData:   Whether sensitive data is masked in log messages.

In certain circumstances it may be beneficial to mask sensitive data, like passwords, in log messages. Set this to true to mask sensitive data. The default is true.

This setting only works on these components: AS3Receiver, AS3Sender, Atom, Client(3DS), FTP, FTPServer, IMAP, OFTPClient, SSHClient, SCP, Server(3DS), Sexec, SFTP, SFTPServer, SSHServer, TCPClient, TCPServer.

UseFIPSCompliantAPI:   Tells the component whether or not to use FIPS certified APIs.

When set to true, the component will utilize the underlying operating system's certified APIs. Java editions, regardless of OS, utilize Bouncy Castle Federal Information Processing Standards (FIPS), while all other Windows editions make use of Microsoft security libraries.

FIPS mode can be enabled by setting the UseFIPSCompliantAPI configuration setting to true. This is a static setting that applies to all instances of all components of the toolkit within the process. It is recommended to enable or disable this setting once before the component has been used to establish a connection. Enabling FIPS while an instance of the component is active and connected may result in unexpected behavior.

For more details, please see the FIPS 140-2 Compliance article.

Note: This setting is applicable only on Windows.

Note: Enabling FIPS compliance requires a special license; please contact sales@nsoftware.com for details.

UseInternalSecurityAPI:   Whether or not to use the system security libraries or an internal implementation.

When set to false, the component will use the system security libraries by default to perform cryptographic functions where applicable. In this case, calls to unmanaged code will be made. In certain environments, this is not desirable. To use a completely managed security implementation, set this setting to true.

Setting this configuration setting to true tells the component to use the internal implementation instead of using the system security libraries.

On Windows, this setting is set to false by default. On Linux/macOS, this setting is set to true by default.

If using the .NET Standard Library, this setting will be true on all platforms. The .NET Standard library does not support using the system security libraries.

Note: This setting is static. The value set is applicable to all components used in the application.

When this value is set, the product's system dynamic link library (DLL) is no longer required as a reference, as all unmanaged code is stored in that file.

Trappable Errors (SSHServer Component)

SSHServer Errors

1201   Could not forward connection. A detailed message follows.
1202   Could not forward connection/channel data. A detailed message follows.
1300   Could not authenticate client.
1301   No server certificate was specified or no private key found.

TCPServer Errors

100   You cannot change the RemotePort at this time. A connection is in progress.
101   You cannot change the RemoteHost at this time. A connection is in progress.
102   The RemoteHost address is invalid (0.0.0.0).
104   TCPServer is already listening.
106   Cannot change LocalPort when TCPServer is listening.
107   Cannot change LocalHost when TCPServer is listening.
108   Cannot change MaxConnections when TCPServer is listening.
112   You cannot change MaxLineLength at this time. A connection is in progress.
116   RemotePort cannot be zero. Please specify a valid service port number.
126   Invalid ConnectionId.
135   Operation would block.

TCP/IP Errors

10004   [10004] Interrupted system call.
10009   [10009] Bad file number.
10013   [10013] Access denied.
10014   [10014] Bad address.
10022   [10022] Invalid argument.
10024   [10024] Too many open files.
10035   [10035] Operation would block.
10036   [10036] Operation now in progress.
10037   [10037] Operation already in progress.
10038   [10038] Socket operation on nonsocket.
10039   [10039] Destination address required.
10040   [10040] Message is too long.
10041   [10041] Protocol wrong type for socket.
10042   [10042] Bad protocol option.
10043   [10043] Protocol is not supported.
10044   [10044] Socket type is not supported.
10045   [10045] Operation is not supported on socket.
10046   [10046] Protocol family is not supported.
10047   [10047] Address family is not supported by protocol family.
10048   [10048] Address already in use.
10049   [10049] Cannot assign requested address.
10050   [10050] Network is down.
10051   [10051] Network is unreachable.
10052   [10052] Net dropped connection or reset.
10053   [10053] Software caused connection abort.
10054   [10054] Connection reset by peer.
10055   [10055] No buffer space available.
10056   [10056] Socket is already connected.
10057   [10057] Socket is not connected.
10058   [10058] Cannot send after socket shutdown.
10059   [10059] Too many references, cannot splice.
10060   [10060] Connection timed out.
10061   [10061] Connection refused.
10062   [10062] Too many levels of symbolic links.
10063   [10063] File name is too long.
10064   [10064] Host is down.
10065   [10065] No route to host.
10066   [10066] Directory is not empty
10067   [10067] Too many processes.
10068   [10068] Too many users.
10069   [10069] Disc Quota Exceeded.
10070   [10070] Stale NFS file handle.
10071   [10071] Too many levels of remote in path.
10091   [10091] Network subsystem is unavailable.
10092   [10092] WINSOCK DLL Version out of range.
10093   [10093] Winsock is not loaded yet.
11001   [11001] Host not found.
11002   [11002] Nonauthoritative 'Host not found' (try again or check DNS setup).
11003   [11003] Nonrecoverable errors: FORMERR, REFUSED, NOTIMP.
11004   [11004] Valid name, no data record (check DNS setup).