SSHServer Class

Properties   Methods   Events   Config Settings   Errors  

The SSHServer class is used to create Secure Shell (SSH) servers. The class 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

ipworksssh.SSHServer

Remarks

The SSHServer class is the Secure Shell (SSH)-enabled equivalent of the IPWorks TCPServer class, 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.

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 class with short descriptions. Click on the links for further details.

Method List

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

Event List

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

Config Settings

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

Channels Property (SSHServer Class)

The collection of currently open channels.

Syntax

public SSHChannelMap getChannels();

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.

ConnectionBacklog Property (SSHServer Class)

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

Syntax

public int getConnectionBacklog();
public void setConnectionBacklog(int connectionBacklog);

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 Class)

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

Syntax

public SSHConnectionMap getConnections();

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.

DefaultAuthMethods Property (SSHServer Class)

The supported authentication methods.

Syntax

public String getDefaultAuthMethods();
public void setDefaultAuthMethods(String defaultAuthMethods);

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 class.

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 class:

DefaultIdleTimeout Property (SSHServer Class)

This property includes the default idle timeout for inactive clients.

Syntax

public int getDefaultIdleTimeout();
public void setDefaultIdleTimeout(int defaultIdleTimeout);

Default Value

0

Remarks

This property specifies the idle timeout (in seconds) for clients. When set to a positive value, the class 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 class to check existing connections.

DefaultTimeout Property (SSHServer Class)

An initial timeout value to be used by incoming connections.

Syntax

public int getDefaultTimeout();
public void setDefaultTimeout(int defaultTimeout);

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 class will wait for the operation to complete before returning control.

The class 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 class 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 Class)

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

Syntax

public String getKeyboardInteractiveMessage();
public void setKeyboardInteractiveMessage(String keyboardInteractiveMessage);

Default Value

""

Remarks

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

KeyboardInteractivePrompts Property (SSHServer Class)

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

Syntax

public SSHPromptList getKeyboardInteractivePrompts();
public void setKeyboardInteractivePrompts(SSHPromptList keyboardInteractivePrompts);

Remarks

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

Listening Property (SSHServer Class)

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

Syntax

public boolean isListening();

Default Value

False

Remarks

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

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

LocalHost Property (SSHServer Class)

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

Syntax

public String getLocalHost();
public void setLocalHost(String localHost);

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 class initiate connections (or accept in the case of server classs) 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 class 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 Class)

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

Syntax

public int getLocalPort();
public void setLocalPort(int localPort);

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 Class)

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

Syntax

public Certificate getSSHCert();
public void setSSHCert(Certificate SSHCert);

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.

SSHCompressionAlgorithms Property (SSHServer Class)

The comma-separated list containing all allowable compression algorithms.

Syntax

public String getSSHCompressionAlgorithms();
public void setSSHCompressionAlgorithms(String SSHCompressionAlgorithms);

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 class 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 class:

• zlib
• zlib@openssh.com
• none

SSHEncryptionAlgorithms Property (SSHServer Class)

The comma-separated list containing all allowable encryption algorithms.

Syntax

public String getSSHEncryptionAlgorithms();
public void setSSHEncryptionAlgorithms(String SSHEncryptionAlgorithms);

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 class 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 class:

ChangeRecordLength Method (SSHServer Class)

Changes the length of received data records.

Syntax

public void changeRecordLength(String channelId, int recordLength);

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 class 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 Class)

Closes an existing SSHChannel .

Syntax

public void closeChannel(String channelId);

Remarks

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

Config Method (SSHServer Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, 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 Class)

This method disconnects the specified client.

Syntax

public void disconnect(String connectionId);

Remarks

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

DoEvents Method (SSHServer Class)

This method processes events from the internal message queue.

Syntax

public void doEvents();

Remarks

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

ExchangeKeys Method (SSHServer Class)

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

Syntax

public void exchangeKeys(String connectionId);

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 Class)

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

Syntax

public String getSSHParam(byte[] payload, String field);

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:

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:

x11-req

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

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:

exec

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

subsystem

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

xon-xoff

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

signal

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

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 Class)

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

Syntax

public byte[] getSSHParamBytes(byte[] payload, String field);

Remarks

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

OpenChannel Method (SSHServer Class)

Opens a new SSHChannel .

Syntax

public String openChannel(String connectionId, String channelType);

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 Class)

This method will reset the class.

Syntax

public void reset();

Remarks

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

SendBytes Method (SSHServer Class)

Sends binary data to the specified channel.

Syntax

public void sendBytes(String channelId, byte[] data);

Remarks

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

SendChannelData Method (SSHServer Class)

Sends data over a Secure Shell (SSH) channel.

Syntax

public void sendChannelData(String channelId, byte[] data);

Remarks

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

SendSSHPacket Method (SSHServer Class)

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

Syntax

public void sendSSHPacket(String channelId, int packetType, byte[] payload);

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 class will finish building the packet, encrypt it for transport, and send it to the server.

SendText Method (SSHServer Class)

Sends text to the specified channel.

Syntax

public void sendText(String channelId, String text);

Remarks

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

SetSSHParam Method (SSHServer Class)

Writes a field to the end of a payload.

Syntax

public byte[] setSSHParam(byte[] payload, String fieldType, String fieldValue);

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:

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 Class)

This method shuts down the server.

Syntax

public void shutdown();

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 Class)

This method starts listening for incoming connections.

Syntax

public void startListening();

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 Class)

This method stops listening for new connections.

Syntax

public void stopListening();

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 Class)

Fired immediately after a connection completes (or fails).

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void connected(SSHServerConnectedEvent e) {}
  ...
}

public class SSHServerConnectedEvent {
  public String connectionId;
  public int statusCode;
  public String description;
  public int certStoreType; //read-write
  public String certStore; //read-write
  public String certPassword; //read-write
  public String certSubject; //read-write
}

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

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:

In Java, the certificate store normally is a file containing certificates and optional private keys.

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:

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

ConnectionRequest Event (SSHServer Class)

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

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void connectionRequest(SSHServerConnectionRequestEvent e) {}
  ...
}

public class SSHServerConnectionRequestEvent {
  public String address;
  public int port;
  public boolean accept; //read-write
}

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 Class)

This event is fired when a connection is closed.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void disconnected(SSHServerDisconnectedEvent e) {}
  ...
}

public class SSHServerDisconnectedEvent {
  public String connectionId;
  public int statusCode;
  public String description;
}

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 Class)

Fired when errors occur during data delivery.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void error(SSHServerErrorEvent e) {}
  ...
}

public class SSHServerErrorEvent {
  public String connectionId;
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class 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 Class)

Fired once for each log message.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void log(SSHServerLogEvent e) {}
  ...
}

public class SSHServerLogEvent {
  public String connectionId;
  public int logLevel;
  public String message;
  public String logType;
}

Remarks

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

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

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 Class)

Fired when a channel is closed.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHChannelClosed(SSHServerSSHChannelClosedEvent e) {}
  ...
}

public class SSHServerSSHChannelClosedEvent {
  public String connectionId;
  public String channelId;
}

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 Class)

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

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHChannelDataIn(SSHServerSSHChannelDataInEvent e) {}
  ...
}

public class SSHServerSSHChannelDataInEvent {
  public String connectionId;
  public String channelId;
  public byte[] data;
}

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 Class)

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

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHChannelEOF(SSHServerSSHChannelEOFEvent e) {}
  ...
}

public class SSHServerSSHChannelEOFEvent {
  public String connectionId;
  public String channelId;
}

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 Class)

Fired when a channel is successfully opened.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHChannelOpened(SSHServerSSHChannelOpenedEvent e) {}
  ...
}

public class SSHServerSSHChannelOpenedEvent {
  public String connectionId;
  public String channelId;
}

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 Class)

Fired when a client attempts to open a new channel.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHChannelOpenRequest(SSHServerSSHChannelOpenRequestEvent e) {}
  ...
}

public class SSHServerSSHChannelOpenRequestEvent {
  public String connectionId;
  public String channelId;
  public String service;
  public byte[] parameters;
  public boolean accept; //read-write
}

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 Class)

Fired when the class is ready to send data.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHChannelReadyToSend(SSHServerSSHChannelReadyToSendEvent e) {}
  ...
}

public class SSHServerSSHChannelReadyToSendEvent {
  public String connectionId;
  public String channelId;
}

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 class 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 Class)

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

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHChannelRequest(SSHServerSSHChannelRequestEvent e) {}
  ...
}

public class SSHServerSSHChannelRequestEvent {
  public String connectionId;
  public String channelId;
  public String requestType;
  public byte[] packet;
  public boolean success; //read-write
}

Remarks

The SSHHost may send requests that affect the status of a particular SSHChannel. Some requests will be automatically handled by the class. 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 class 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 Class)

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

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHChannelRequested(SSHServerSSHChannelRequestedEvent e) {}
  ...
}

public class SSHServerSSHChannelRequestedEvent {
  public String connectionId;
  public String channelId;
  public String requestType;
  public byte[] packet;
}

Remarks

The SSHHost may send requests that affect the status of a particular SSHChannel. Some requests will be automatically handled by the class. 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 Class)

Fired when a client requests a service to be started.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHServiceRequest(SSHServerSSHServiceRequestEvent e) {}
  ...
}

public class SSHServerSSHServiceRequestEvent {
  public String connectionId;
  public String service;
  public boolean accept; //read-write
}

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 Class)

Fired to show the progress of the secure connection.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHStatus(SSHServerSSHStatusEvent e) {}
  ...
}

public class SSHServerSSHStatusEvent {
  public String connectionId;
  public String message;
}

Remarks

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

SSHTunnelClosed Event (SSHServer Class)

Fired when a connected client attempts to close a tunnel.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHTunnelClosed(SSHServerSSHTunnelClosedEvent e) {}
  ...
}

public class SSHServerSSHTunnelClosedEvent {
  public String connectionId;
  public String address;
  public int port;
}

Remarks

SSHTunnelRequested Event (SSHServer Class)

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

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHTunnelRequested(SSHServerSSHTunnelRequestedEvent e) {}
  ...
}

public class SSHServerSSHTunnelRequestedEvent {
  public String connectionId;
  public int direction;
  public String address;
  public int port; //read-write
  public boolean accept; //read-write
}

Remarks

SSHUserAuthRequest Event (SSHServer Class)

Fired when a client attempts to authenticate a connection.

Syntax

public class DefaultSSHServerEventListener implements SSHServerEventListener {
  ...
  public void SSHUserAuthRequest(SSHServerSSHUserAuthRequestEvent e) {}
  ...
}

public class SSHServerSSHUserAuthRequestEvent {
  public String connectionId;
  public String user;
  public String service;
  public String authMethod;
  public String authParam;
  public boolean accept; //read-write
  public boolean partialSuccess; //read-write
  public String availableMethods; //read-write
  public String keyAlgorithm;
}

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 class 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 class:

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.

Fields

Constructors

public Certificate();

public Certificate( certificateFile);

public Certificate( encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

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.

Fields

SSHConnection Type

A currently connected client.

Remarks

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

Fields

Constructors

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.

Fields

Constructors

public SSHPrompt();

public SSHPrompt( prompt,  echo);

Config Settings (SSHServer Class)

SSHServer Config Settings

*SSH-1.99-*,*SSH-2.0-*,*SSH-2.99-*

TCPServer Config Settings

Base Config Settings

Trappable Errors (SSHServer Class)

SSHServer Errors

TCPServer Errors

TCP/IP Errors