SSHReverseTunnel Component

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The SSHReverseTunnel component provides a simple way to establish a reverse tunnel with a Secure Shell (SSH) host.

Syntax

nsoftware.IPWorksSSH.SSHReverseTunnel

Remarks

The SSHReverseTunnel component may be used to establish a reverse tunnel with a Secure Shell (SSH) host. The SSH host will listen for incoming connections on the specified port and forward traffic to the component through the SSH tunnel.

The SSHHost and SSHPort properties specify which Secure Shell (SSH) server to use. The SSHUser and SSHPassword properties allow the client to authenticate itself with the server. The SSHServerAuthentication event or SSHAcceptServerHostKey property allow you to check the server identity. Finally, the SSHStatus event provides information about the SSH handshake.

To begin, call SSHLogon to connect to the SSH host. After this method returns, the connectionto the SSH server is successfully established. Call RequestForwarding to establish a reverse tunnel. This method takes parameters to tell the SSH host on which port to listen.

The component has two modes that allow data to be dealt with directly from the events, or automatically forwarded on to a different endpoint.

Event Based Operation

In this mode, any data received by the component over the tunnel causes the events of the component to fire. For instance:

SSHReverseTunnel.RequestForwarding("0.0.0.0", 777, "", 0);

In the above code, forwarding is requested from port 777 on the SSHHost. Any data received on port 777 by the SSHHost will be sent to the component. In the above code, the last two parameters are empty and 0, indicating to the component that no local forwarding is requested.

Once RequestForwarding returns, the Secure Shell (SSH) reverse tunnel is established. Any connection made to the SSH host on the specified port will then trigger the component's events to fire, allowing you to handle the connection request and data.

When a client connects to the SSH host on the specified port, the SSHChannelOpenRequest event will fire. Within this event, choose to accept or reject the connection by setting the Accept parameter. This event contains details about the connection that may be used when determining whether to accept the connection.

After the channel is established, data are received through the SSHChannelData event. Call the SendChannelData method to send data over the channel, and call the CloseChannel method to close the channel.

Local Forwarding

In this mode, any data received by the component is automatically forwarded to a separate endpoint. This allows the component to act as a sort of proxy. There is no need to handle data directly in this case. For instance: SSHReverseTunnel.RequestForwarding("0.0.0.0", 777, "nsoftware.com", 80);

In the above code, forwarding is requested from port 777 on SSHHost. The component is instructed to establish a connection to "nsoftware.com" on port 80 when a client connects to SSHHost on port 777. Any data received from the client connected to SSHHost on port 777 will automatically be forwarded to "nsoftware.com" on port 80. Any data received back from "nsoftware.com" on port 80 will be sent back to the connected client.

In this mode, data may flow freely from the client connected to the SSHHost to the endpoint specified in the RequestForwarding method without any additional code required.

Note: The following events are applicable when a connection is made to the SSH host:

• SSHChannelClosed
• SSHChannelData
• SSHChannelEOF
• SSHChannelOpened
• SSHChannelOpenRequest
• SSHChannelReadyToSend
• SSHChannelRequested

To stop a previously established reverse tunnel, call the CancelForwarding method.

Property List

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

Method List

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

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.

Config Settings

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

Channels Property (SSHReverseTunnel Component)

A collection of currently open channels.

Syntax

• C#
• VB.NET

public SSHRTChannelMap Channels { get; }

Public ReadOnly Property Channels As SSHRTChannelMap

Remarks

This property is a collection of established channels. When a client connects to an existing reverse tunnel, a new channel is requested and added to this collection. This collection is a hashtable for which the channel's Id string is used as the key to the desired Secure Shell (SSH) channel object.

Example. Sending Data to a Channel

channels["1"].DataToSend = "channel specific data";

This property is read-only.

Connected Property (SSHReverseTunnel Component)

The component to be connected.

Syntax

• C#
• VB.NET

public bool Connected { get; }

Public ReadOnly Property Connected As Boolean

Default Value

False

Remarks

This property is used to determine whether or not the component is connected to the remote host. Use the SSHLogon and SSHLogoff methods to manage the connection.

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

Firewall Property (SSHReverseTunnel Component)

A set of properties related to firewall access.

Syntax

• C#
• VB.NET

public Firewall Firewall { get; set; }

Public Property Firewall As Firewall

Remarks

This is a Firewall-type property, which contains fields describing the firewall through which the component will attempt to connect.

LocalHost Property (SSHReverseTunnel Component)

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

Syntax

• C#
• VB.NET

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 (SSHReverseTunnel Component)

The TCP port in the local host where the component binds.

Syntax

• C#
• VB.NET

public int LocalPort { get; set; }

Public Property LocalPort As Integer

Default Value

0

Remarks

This property must be set before a connection is attempted. It instructs the component to bind to a specific port (or communication endpoint) in the local machine.

Setting this property to 0 (default) enables the system to choose an open port at random. The chosen port will be returned by the LocalPort property after the connection is established.

LocalPort cannot be changed once a connection is made. Any attempt to set this property when a connection is active will generate an error.

This property is useful when trying to connect to services that require a trusted port on the client side.

SSHAcceptServerHostKey Property (SSHReverseTunnel Component)

Instructs the component to accept the server host key that matches the supplied key.

Syntax

• C#
• VB.NET

public Certificate SSHAcceptServerHostKey { get; set; }

Public Property SSHAcceptServerHostKey As Certificate

Remarks

If the host key that will be used by the server is known in advance, this property may be set to accept the expected key. Otherwise, the SSHServerAuthentication event should be trapped, and the key should be accepted or refused in the event.

If this property is not set and the SSHServerAuthentication event is not trapped, the server will not be authenticated and the connection will be terminated by the client.

SSHAuthMode Property (SSHReverseTunnel Component)

The authentication method to be used with the component when calling SSHLogon .

Syntax

• C#
• VB.NET

public SSHReverseTunnelSSHAuthModes SSHAuthMode { get; set; }

enum SSHReverseTunnelSSHAuthModes {
  amNone,
  amMultiFactor,
  amPassword,
  amPublicKey,
  amKeyboardInteractive,
  amGSSAPIWithMic,
  amGSSAPIKeyex,
  amCustom
}

Public Property SSHAuthMode As SshreversetunnelSSHAuthModes

Enum SSHReverseTunnelSSHAuthModes
  amNone
  amMultiFactor
  amPassword
  amPublicKey
  amKeyboardInteractive
  amGSSAPIWithMic
  amGSSAPIKeyex
  amCustom
End Enum

Default Value

2

Remarks

The Secure Shell (SSH) Authentication specification (RFC 4252) specifies multiple methods by which a user can be authenticated by an SSH server. When a call is made to SSHLogon, the component will connect to the SSH server and establish the security layer. After the connection has been secured, the client will send an authentication request to the SSHHost containing the SSHUser. The server will respond containing a list of methods by which that user may be authenticated.

The component will attempt to authenticate the user by one of those methods based on the value of SSHAuthMode and other property values supplied by the user. Currently, the component supports the following authentication methods:

Example 1. User/Password Authentication: Control.SSHAuthMode = SftpSSHAuthModes.amPassword Control.SSHUser = "username" Control.SSHPassword = "password" Control.SSHLogon("server", 22) Example 2. Public Key Authentication: Control.SSHAuthMode = SftpSSHAuthModes.amPublicKey Control.SSHUser = "username" Control.SSHCert = New Certificate(CertStoreTypes.cstPFXFile, "cert.pfx", "certpassword", "*") Control.SSHLogon("server", 22)

SSHCert Property (SSHReverseTunnel Component)

A certificate to be used for authenticating the SSHUser .

Syntax

• C#
• VB.NET

public Certificate SSHCert { get; set; }

Public Property SSHCert As Certificate

Remarks

To use public key authentication, SSHCert must contain a Certificate with a valid private key. The certificate's public key value is sent to the server along with a signature produced using the private key. The server will first check to see if the public key values match what is known for the user, and then it will attempt to use those values to verify the signature.

Example 1. User/Password Authentication: Control.SSHAuthMode = SftpSSHAuthModes.amPassword Control.SSHUser = "username" Control.SSHPassword = "password" Control.SSHLogon("server", 22) Example 2. Public Key Authentication: Control.SSHAuthMode = SftpSSHAuthModes.amPublicKey Control.SSHUser = "username" Control.SSHCert = New Certificate(CertStoreTypes.cstPFXFile, "cert.pfx", "certpassword", "*") Control.SSHLogon("server", 22)

SSHCompressionAlgorithms Property (SSHReverseTunnel Component)

The comma-separated list containing all allowable compression algorithms.

Syntax

• C#
• VB.NET

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 (SSHReverseTunnel Component)

The comma-separated list containing all allowable encryption algorithms.

Syntax

• C#
• VB.NET

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:

SSHHost Property (SSHReverseTunnel Component)

The address of the Secure Shell (SSH) host.

Syntax

• C#
• VB.NET

public string SSHHost { get; set; }

Public Property SSHHost As String

Default Value

""

Remarks

The SSHHost property specifies the IP address (IP number in dotted internet format) or domain name of the remote host. It is set before a connection is attempted and cannot be changed once a connection is established.

If the SSHHost property is set to a domain name, a DNS request is initiated, and upon successful termination of the request, the SSHHost property is set to the corresponding address. If the search is not successful, an error is returned.

The SSHHost must be the same host that will be assumed for SSH as for the remote service being connected to.

SSHPassword Property (SSHReverseTunnel Component)

The password for Secure Shell (SSH) password-based authentication.

Syntax

• C#
• VB.NET

public string SSHPassword { get; set; }

Public Property SSHPassword As String

Default Value

""

Remarks

SSHPassword specifies the password that is used to authenticate the client to the SSH server.

SSHPort Property (SSHReverseTunnel Component)

The port on the Secure Shell (SSH) server where the SSH service is running; by default, 22.

Syntax

• C#
• VB.NET

public int SSHPort { get; set; }

Public Property SSHPort As Integer

Default Value

22

Remarks

The SSHPort specifies a service port on the SSH host to connect to.

A valid port number (a value between 1 and 65535) is required for the connection to take place. The property must be set before a connection is attempted and cannot be changed once a connection is established. Any attempt to change this property while connected will fail with an error.

SSHUser Property (SSHReverseTunnel Component)

The username for Secure Shell (SSH) authentication.

Syntax

• C#
• VB.NET

public string SSHUser { get; set; }

Public Property SSHUser As String

Default Value

""

Remarks

SSHUser specifies the username that is used to authenticate the client to the SSH server. This property is required.

Example 1. User/Password Authentication: Control.SSHAuthMode = SftpSSHAuthModes.amPassword Control.SSHUser = "username" Control.SSHPassword = "password" Control.SSHLogon("server", 22) Example 2. Public Key Authentication: Control.SSHAuthMode = SftpSSHAuthModes.amPublicKey Control.SSHUser = "username" Control.SSHCert = New Certificate(CertStoreTypes.cstPFXFile, "cert.pfx", "certpassword", "*") Control.SSHLogon("server", 22)

Timeout Property (SSHReverseTunnel Component)

This property includes the timeout for the component.

Syntax

• C#
• VB.NET

public int Timeout { get; set; }

Public Property Timeout As Integer

Default Value

60

Remarks

If the Timeout property 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 the Timeout property is 60 seconds.

CancelForwarding Method (SSHReverseTunnel Component)

Requests the server to stop forwarding a remote Transmission Control Protocol (TCP)/IP port.

Syntax

• C#
• VB.NET

public void CancelForwarding(string address, int port);

Async Version
public async Task CancelForwarding(string address, int port);
public async Task CancelForwarding(string address, int port, CancellationToken cancellationToken);

Public Sub CancelForwarding(ByVal Address As String, ByVal Port As Integer)

Async Version
Public Sub CancelForwarding(ByVal Address As String, ByVal Port As Integer) As Task
Public Sub CancelForwarding(ByVal Address As String, ByVal Port As Integer, cancellationToken As CancellationToken) As Task

Remarks

The CancelForwarding cancels a previous TCP/IP port forwarding request. When calling it, provide the same argument values you provided on the RequestForwarding call.

CloseChannel Method (SSHReverseTunnel Component)

Closes a existing SSHChannel .

Syntax

• C#
• VB.NET

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 (SSHReverseTunnel Component)

Sets or retrieves a configuration setting.

Syntax

• C#
• VB.NET

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.

DecodePacket Method (SSHReverseTunnel Component)

Decodes a hex-encoded Secure Shell (SSH) packet

Syntax

• C#
• VB.NET

public byte[] DecodePacket(string encodedPacket);

Async Version
public async Task<byte[]> DecodePacket(string encodedPacket);
public async Task<byte[]> DecodePacket(string encodedPacket, CancellationToken cancellationToken);

Public Function DecodePacket(ByVal EncodedPacket As String) As String

Async Version
Public Function DecodePacket(ByVal EncodedPacket As String) As Task(Of String)
Public Function DecodePacket(ByVal EncodedPacket As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

This method is used to decode an SSH packet created by EncodePacket.

Note: This method is applicable only for reading and creating Secure Shell (SSH) packets for use within the SSHCustomAuth event.

DoEvents Method (SSHReverseTunnel Component)

This method processes events from the internal message queue.

Syntax

• C#
• VB.NET

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.

EncodePacket Method (SSHReverseTunnel Component)

Hex encodes a Secure Shell (SSH) packet.

Syntax

• C#
• VB.NET

public string EncodePacket(byte[] packet);

Async Version
public async Task<string> EncodePacket(byte[] packet);
public async Task<string> EncodePacket(byte[] packet, CancellationToken cancellationToken);

Public Function EncodePacket(ByVal Packet As String) As String

Async Version
Public Function EncodePacket(ByVal Packet As String) As Task(Of String)
Public Function EncodePacket(ByVal Packet As String, cancellationToken As CancellationToken) As Task(Of String)

Remarks

This method is used to encode a raw SSH packet created by SetSSHParam.

Note: This method is applicable only for reading and creating Secure Shell (SSH) packets for use within the SSHCustomAuth event.

ExchangeKeys Method (SSHReverseTunnel Component)

Causes the component to exchange a new set of session keys with the SSHHost .

Syntax

• C#
• VB.NET

public void ExchangeKeys();

Async Version
public async Task ExchangeKeys();
public async Task ExchangeKeys(CancellationToken cancellationToken);

Public Sub ExchangeKeys()

Async Version
Public Sub ExchangeKeys() As Task
Public Sub ExchangeKeys(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 user to start such a renegotiation with the SSHHost. 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. Doing so makes it more difficult to break the security of data-intensive or long-lived connections.

GetSSHParam Method (SSHReverseTunnel Component)

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

Syntax

• C#
• VB.NET

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:

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.

Note: This method is applicable only for reading and creating Secure Shell (SSH) packets for use within the SSHCustomAuth event.

GetSSHParamBytes Method (SSHReverseTunnel Component)

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

Syntax

• C#
• VB.NET

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.

Note: This method is applicable only for reading and creating Secure Shell (SSH) packets for use within the SSHCustomAuth event.

RequestForwarding Method (SSHReverseTunnel Component)

Requests the server to forward a remote Transmission Control Protocol (TCP)/IP port.

Syntax

• C#
• VB.NET

public void RequestForwarding(string address, int port, string forwardingHost, int forwardingPort);

Async Version
public async Task RequestForwarding(string address, int port, string forwardingHost, int forwardingPort);
public async Task RequestForwarding(string address, int port, string forwardingHost, int forwardingPort, CancellationToken cancellationToken);

Public Sub RequestForwarding(ByVal Address As String, ByVal Port As Integer, ByVal ForwardingHost As String, ByVal ForwardingPort As Integer)

Async Version
Public Sub RequestForwarding(ByVal Address As String, ByVal Port As Integer, ByVal ForwardingHost As String, ByVal ForwardingPort As Integer) As Task
Public Sub RequestForwarding(ByVal Address As String, ByVal Port As Integer, ByVal ForwardingHost As String, ByVal ForwardingPort As Integer, cancellationToken As CancellationToken) As Task

Remarks

The RequestForwarding method asks the server to listen at the specified TCP/IP Address and Port for connection requests and then forward them as new Secure Shell (SSH) channels to the component.

ForwardingHost and ForwardingPort may be used to specify an address and port to which traffic will automatically be forwarded. If automatic forwarding is not desired, specify an empty string ("") for the ForwardingHost parameter.

The Address argument can be specified in different ways:

• "" means that connections are to be accepted on all protocol families supported by the server.
• "0.0.0.0" means to listen on all IPv4 addresses.
• "::" means to listen on all IPv6 addresses.
• "localhost" means to listen on all protocol families supported by the Secure Shell (SSH) implementation on loopback addresses only.
• "127.0.0.1" and "::1" indicate listening on the loopback interfaces for IPv4 and IPv6, respectively.

Passing a value of 0 for the Port parameter instructs the server to assign a port. In this case, query the ForwardedPort setting to determine the port that was assigned by the server.

The component has two modes that allow data to be dealt with directly from the events, or automatically forwarded on to a different endpoint.

Event Based Operation

In this mode, any data received by the component over the tunnel causes the events of the component to fire. For instance:

SSHReverseTunnel.RequestForwarding("0.0.0.0", 777, "", 0);

In the above code, forwarding is requested from port 777 on the SSHHost. Any data received on port 777 by the SSHHost will be sent to the component. In the above code, the last two parameters are empty and 0, indicating to the component that no local forwarding is requested.

Once RequestForwarding returns, the Secure Shell (SSH) reverse tunnel is established. Any connection made to the SSH host on the specified port will then trigger the component's events to fire, allowing you to handle the connection request and data.

When a client connects to the SSH host on the specified port, the SSHChannelOpenRequest event will fire. Within this event, choose to accept or reject the connection by setting the Accept parameter. This event contains details about the connection that may be used when determining whether to accept the connection.

After the channel is established, data are received through the SSHChannelData event. Call the SendChannelData method to send data over the channel, and call the CloseChannel method to close the channel.

Local Forwarding

In this mode, any data received by the component is automatically forwarded to a separate endpoint. This allows the component to act as a sort of proxy. There is no need to handle data directly in this case. For instance: SSHReverseTunnel.RequestForwarding("0.0.0.0", 777, "nsoftware.com", 80);

In the above code, forwarding is requested from port 777 on SSHHost. The component is instructed to establish a connection to "nsoftware.com" on port 80 when a client connects to SSHHost on port 777. Any data received from the client connected to SSHHost on port 777 will automatically be forwarded to "nsoftware.com" on port 80. Any data received back from "nsoftware.com" on port 80 will be sent back to the connected client.

In this mode, data may flow freely from the client connected to the SSHHost to the endpoint specified in the RequestForwarding method without any additional code required.

Reset Method (SSHReverseTunnel Component)

This method will reset the component.

Syntax

• C#
• VB.NET

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.

SendChannelData Method (SSHReverseTunnel Component)

Sends data over a Secure Shell (SSH) channel.

Syntax

• C#
• VB.NET

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.

SetSSHParam Method (SSHReverseTunnel Component)

Writes a field to the end of a payload.

Syntax

• C#
• VB.NET

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:

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

Note: This method is applicable only for reading and creating Secure Shell (SSH) packets for use within the SSHCustomAuth event.

SSHLogoff Method (SSHReverseTunnel Component)

Logs off from the Secure Shell (SSH) server.

Syntax

• C#
• VB.NET

public void SSHLogoff();

Async Version
public async Task SSHLogoff();
public async Task SSHLogoff(CancellationToken cancellationToken);

Public Sub SSHLogoff()

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

Remarks

Logs off from the SSH server. If that fails, the connection is terminated by the local host.

SSHLogon Method (SSHReverseTunnel Component)

Logs on to the SSHHost using the current SSHUser and SSHPassword .

Syntax

• C#
• VB.NET

public void SSHLogon(string SSHHost, int SSHPort);

Async Version
public async Task SSHLogon(string SSHHost, int SSHPort);
public async Task SSHLogon(string SSHHost, int SSHPort, CancellationToken cancellationToken);

Public Sub SSHLogon(ByVal SSHHost As String, ByVal SSHPort As Integer)

Async Version
Public Sub SSHLogon(ByVal SSHHost As String, ByVal SSHPort As Integer) As Task
Public Sub SSHLogon(ByVal SSHHost As String, ByVal SSHPort As Integer, cancellationToken As CancellationToken) As Task

Remarks

Logs on to the Secure Shell (SSH) server using the current SSHUser and SSHPassword. This will perform the SSH handshake and authentication.

Example. Logging On:

SSHClient.SSHUser = "username" SSHClient.SSHPassword = "password" SSHClient.SSHLogon("sshHost", sshPort)

Connected Event (SSHReverseTunnel Component)

Fired immediately after a connection completes (or fails).

Syntax

• C#
• VB.NET

public event OnConnectedHandler OnConnected;

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

public class SSHReverseTunnelConnectedEventArgs : EventArgs {
  public int StatusCode { get; }
  public string Description { get; }
}

Public Event OnConnected As OnConnectedHandler

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

Public Class SSHReverseTunnelConnectedEventArgs Inherits EventArgs
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description 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 Transmission Control Protocol (TCP)/IP stack. Description contains a description of this code. The value of StatusCode is equal to the value of the error.

Please refer to the Error Codes section for more information.

ConnectionStatus Event (SSHReverseTunnel Component)

Fired to indicate changes in the connection state.

Syntax

• C#
• VB.NET

public event OnConnectionStatusHandler OnConnectionStatus;

public delegate void OnConnectionStatusHandler(object sender, SSHReverseTunnelConnectionStatusEventArgs e);

public class SSHReverseTunnelConnectionStatusEventArgs : EventArgs {
  public string ConnectionEvent { get; }
  public int StatusCode { get; }
  public string Description { get; }
}

Public Event OnConnectionStatus As OnConnectionStatusHandler

Public Delegate Sub OnConnectionStatusHandler(sender As Object, e As SSHReverseTunnelConnectionStatusEventArgs)

Public Class SSHReverseTunnelConnectionStatusEventArgs Inherits EventArgs
  Public ReadOnly Property ConnectionEvent As String
  Public ReadOnly Property StatusCode As Integer
  Public ReadOnly Property Description As String
End Class

Remarks

This event is fired when the connection state changes: for example, completion of a firewall or proxy connection or completion of a security handshake.

The ConnectionEvent parameter indicates the type of connection event. Values may include the following:

Disconnected Event (SSHReverseTunnel Component)

Fired when a connection is closed.

Syntax

• C#
• VB.NET

public event OnDisconnectedHandler OnDisconnected;

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

public class SSHReverseTunnelDisconnectedEventArgs : EventArgs {
  public int StatusCode { get; }
  public string Description { get; }
}

Public Event OnDisconnected As OnDisconnectedHandler

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

Public Class SSHReverseTunnelDisconnectedEventArgs Inherits EventArgs
  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 Transmission Control Protocol (TCP/IP) subsystem. Description contains a description of this code. The value of StatusCode is equal to the value of the TCP/IP error.

Please refer to the Error Codes section for more information.

Error Event (SSHReverseTunnel Component)

Fired when information is available about errors during data delivery.

Syntax

• C#
• VB.NET

public event OnErrorHandler OnError;

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

public class SSHReverseTunnelErrorEventArgs : EventArgs {
  public int ErrorCode { get; }
  public string Description { get; }
}

Public Event OnError As OnErrorHandler

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

Public Class SSHReverseTunnelErrorEventArgs Inherits EventArgs
  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.

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

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

The ErrorCode parameter contains an error code, and the Description parameter 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 (SSHReverseTunnel Component)

Fired once for each log message.

Syntax

• C#
• VB.NET

public event OnLogHandler OnLog;

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

public class SSHReverseTunnelLogEventArgs : EventArgs {
  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 SSHReverseTunnelLogEventArgs)

Public Class SSHReverseTunnelLogEventArgs Inherits EventArgs
  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:

Message is the log message.

LogType is reserved for future use.

ReconnectAttempt Event (SSHReverseTunnel Component)

Fired when attempting to reconnect.

Syntax

• C#
• VB.NET

public event OnReconnectAttemptHandler OnReconnectAttempt;

public delegate void OnReconnectAttemptHandler(object sender, SSHReverseTunnelReconnectAttemptEventArgs e);

public class SSHReverseTunnelReconnectAttemptEventArgs : EventArgs {
  public string Host { get; }
  public int Port { get; }
  public int RetryCount { get; }
  public int RetriesRemaining { get; }
  public int MaxRetryCount { get; }
  public int RetryInterval { get; }
  public int RetryType { get; }
  public int RemoteListeningPort { get; }
  public bool Cancel { get; set; }
}

Public Event OnReconnectAttempt As OnReconnectAttemptHandler

Public Delegate Sub OnReconnectAttemptHandler(sender As Object, e As SSHReverseTunnelReconnectAttemptEventArgs)

Public Class SSHReverseTunnelReconnectAttemptEventArgs Inherits EventArgs
  Public ReadOnly Property Host As String
  Public ReadOnly Property Port As Integer
  Public ReadOnly Property RetryCount As Integer
  Public ReadOnly Property RetriesRemaining As Integer
  Public ReadOnly Property MaxRetryCount As Integer
  Public ReadOnly Property RetryInterval As Integer
  Public ReadOnly Property RetryType As Integer
  Public ReadOnly Property RemoteListeningPort As Integer
  Public Property Cancel As Boolean
End Class

Remarks

This event fires both when attempting to reconnect to the SSHHost and when reestablishing a Secure Shell (SSH) tunnel.

This is applicable only when AutoReconnect is enabled. To determine which type of connection is being established check the RetryType parameter.

The following table provides details about the parameters:

SSHChannelClosed Event (SSHReverseTunnel Component)

Fired when a channel is closed.

Syntax

• C#
• VB.NET

public event OnSSHChannelClosedHandler OnSSHChannelClosed;

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

public class SSHReverseTunnelSSHChannelClosedEventArgs : EventArgs {
  public string ChannelId { get; }
}

Public Event OnSSHChannelClosed As OnSSHChannelClosedHandler

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

Public Class SSHReverseTunnelSSHChannelClosedEventArgs Inherits EventArgs
  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.

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.

SSHChannelData Event (SSHReverseTunnel Component)

Fired when the SSHHost sends channel data to the client.

Syntax

• C#
• VB.NET

public event OnSSHChannelDataHandler OnSSHChannelData;

public delegate void OnSSHChannelDataHandler(object sender, SSHReverseTunnelSSHChannelDataEventArgs e);

public class SSHReverseTunnelSSHChannelDataEventArgs : EventArgs {
  public string ChannelId { get; }
  public string ChannelData { get; }
  public byte[] ChannelDataB { get; }
  public bool ChannelDataEOLFound { get; }
}

Public Event OnSSHChannelData As OnSSHChannelDataHandler

Public Delegate Sub OnSSHChannelDataHandler(sender As Object, e As SSHReverseTunnelSSHChannelDataEventArgs)

Public Class SSHReverseTunnelSSHChannelDataEventArgs Inherits EventArgs
  Public ReadOnly Property ChannelId As String
  Public ReadOnly Property ChannelData As String
  Public ReadOnly Property ChannelDataB As Byte()
  Public ReadOnly Property ChannelDataEOLFound As Boolean
End Class

Remarks

The SSHChannelData event will fire as data are received for the given ChannelId. ChannelData will contain the decrypted contents of the Secure Shell (SSH) packet.

ChannelDataEOLFound indicates whether or not the ChannelEOL string for the channel was found at the end of ChannelData. If the ChannelEOL string was found, then ChannelDataEOLFound is True.

If ChannelData is part of a data portion of a length that is larger than the MaxChannelLength for the Channel with no ChannelEOL strings in it, then ChannelDataEOLFound is False.

Note: This means that one of more SSHChannelData events with ChannelDataEOLFound set to False can be received.

If the ChannelEOL property for the Channel is "" (empty string), then ChannelDataEOLFound can be disregarded (it is always True).

SSHChannelEOF Event (SSHReverseTunnel Component)

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

Syntax

• C#
• VB.NET

public event OnSSHChannelEOFHandler OnSSHChannelEOF;

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

public class SSHReverseTunnelSSHChannelEOFEventArgs : EventArgs {
  public string ChannelId { get; }
}

Public Event OnSSHChannelEOF As OnSSHChannelEOFHandler

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

Public Class SSHReverseTunnelSSHChannelEOFEventArgs Inherits EventArgs
  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 Secure Shell (SSH) connection is reached.

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 (SSHReverseTunnel Component)

Fired when a channel is successfully opened.

Syntax

• C#
• VB.NET

public event OnSSHChannelOpenedHandler OnSSHChannelOpened;

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

public class SSHReverseTunnelSSHChannelOpenedEventArgs : EventArgs {
  public string ChannelId { get; }
}

Public Event OnSSHChannelOpened As OnSSHChannelOpenedHandler

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

Public Class SSHReverseTunnelSSHChannelOpenedEventArgs Inherits EventArgs
  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.

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 (SSHReverseTunnel Component)

Fired when the peer attempts to open a new channel.

Syntax

• C#
• VB.NET

public event OnSSHChannelOpenRequestHandler OnSSHChannelOpenRequest;

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

public class SSHReverseTunnelSSHChannelOpenRequestEventArgs : EventArgs {
  public string ChannelId { get; }
  public string Service { get; }
  public string ConnectedAddress { get; }
  public int ConnectedPort { get; }
  public string OriginAddress { get; }
  public int OriginPort { get; }
  public bool Accept { get; set; }
}

Public Event OnSSHChannelOpenRequest As OnSSHChannelOpenRequestHandler

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

Public Class SSHReverseTunnelSSHChannelOpenRequestEventArgs Inherits EventArgs
  Public ReadOnly Property ChannelId As String
  Public ReadOnly Property Service As String
  Public ReadOnly Property ConnectedAddress As String
  Public ReadOnly Property ConnectedPort As Integer
  Public ReadOnly Property OriginAddress As String
  Public ReadOnly Property OriginPort As Integer
  Public Property Accept As Boolean
End Class

Remarks

This event is fired whenever a peer 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. Usually, this will be "forwarded-tcpip", in which case ConnectedAddress and ConnectedPort will contain the remote Transmission Control Protocol (TCP)/IP address and port on the peer to which the connection was established; OriginAddress and OriginPort contain the originating TCP/IP address and port of the connection.

By default, Accept is True and the channel will be opened. Set Accept to False to reject the request.

SSHChannelReadyToSend Event (SSHReverseTunnel Component)

Fired when the component is ready to send data.

Syntax

• C#
• VB.NET

public event OnSSHChannelReadyToSendHandler OnSSHChannelReadyToSend;

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

public class SSHReverseTunnelSSHChannelReadyToSendEventArgs : EventArgs {
  public string ChannelId { get; }
}

Public Event OnSSHChannelReadyToSend As OnSSHChannelReadyToSendHandler

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

Public Class SSHReverseTunnelSSHChannelReadyToSendEventArgs Inherits EventArgs
  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.

When a channel is opened, this event will fire after 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 (SSHReverseTunnel Component)

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

Syntax

• C#
• VB.NET

public event OnSSHChannelRequestHandler OnSSHChannelRequest;

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

public class SSHReverseTunnelSSHChannelRequestEventArgs : EventArgs {
  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 SSHReverseTunnelSSHChannelRequestEventArgs)

Public Class SSHReverseTunnelSSHChannelRequestEventArgs Inherits EventArgs
  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.

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 (SSHReverseTunnel Component)

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

Syntax

• C#
• VB.NET

public event OnSSHChannelRequestedHandler OnSSHChannelRequested;

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

public class SSHReverseTunnelSSHChannelRequestedEventArgs : EventArgs {
  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 SSHReverseTunnelSSHChannelRequestedEventArgs)

Public Class SSHReverseTunnelSSHChannelRequestedEventArgs Inherits EventArgs
  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.

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.

SSHCustomAuth Event (SSHReverseTunnel Component)

Fired when the component is doing a custom authentication.

Syntax

• C#
• VB.NET

public event OnSSHCustomAuthHandler OnSSHCustomAuth;

public delegate void OnSSHCustomAuthHandler(object sender, SSHReverseTunnelSSHCustomAuthEventArgs e);

public class SSHReverseTunnelSSHCustomAuthEventArgs : EventArgs {
  public string Packet { get; set; }
}

Public Event OnSSHCustomAuth As OnSSHCustomAuthHandler

Public Delegate Sub OnSSHCustomAuthHandler(sender As Object, e As SSHReverseTunnelSSHCustomAuthEventArgs)

Public Class SSHReverseTunnelSSHCustomAuthEventArgs Inherits EventArgs
  Public Property Packet As String
End Class

Remarks

SSHCustomAuth is fired during the user authentication stage of the Secure Shell (SSH) logon process if SSHAuthMode is set to amCustom. Packet contains the last raw SSH packet sent by the server, in HEX-encoded format.

The client should create a new raw SSH packet to send to the server and set Packet to the HEX-encoded representation of the packet to send.

In all cases, Packet will start with the message type field.

To read the incoming packet, call DecodePacket and then use the GetSSHParam and GetSSHParamBytes methods. To create a packet, use the SetSSHParam method and then call EncodePacket to obtain a HEX-encoded value and assign this to the Packet parameter.

SSHKeyboardInteractive Event (SSHReverseTunnel Component)

Fired when the component receives a request for user input from the server.

Syntax

• C#
• VB.NET

public event OnSSHKeyboardInteractiveHandler OnSSHKeyboardInteractive;

public delegate void OnSSHKeyboardInteractiveHandler(object sender, SSHReverseTunnelSSHKeyboardInteractiveEventArgs e);

public class SSHReverseTunnelSSHKeyboardInteractiveEventArgs : EventArgs {
  public string Name { get; }
  public string Instructions { get; }
  public string Prompt { get; }
  public string Response { get; set; }
  public bool EchoResponse { get; }
}

Public Event OnSSHKeyboardInteractive As OnSSHKeyboardInteractiveHandler

Public Delegate Sub OnSSHKeyboardInteractiveHandler(sender As Object, e As SSHReverseTunnelSSHKeyboardInteractiveEventArgs)

Public Class SSHReverseTunnelSSHKeyboardInteractiveEventArgs Inherits EventArgs
  Public ReadOnly Property Name As String
  Public ReadOnly Property Instructions As String
  Public ReadOnly Property Prompt As String
  Public Property Response As String
  Public ReadOnly Property EchoResponse As Boolean
End Class

Remarks

SSHKeyboardInteractive is fired during the user authentication stage of the Secure Shell (SSH) logon process. During authentication, the component will request a list of available authentication methods for the SSHUser. For example, if the SSHHost responds with "keyboard-interactive", the component will fire this event to allow the client application to set the password.

During authentication, the SSH server may respond with a request for the user's authentication information. Name is a server-provided value associated with the authentication method such as "CRYPTOCard Authentication". Instructions will contain specific instructions, also supplied by the server, for how the user should respond.

Along with these values, the server will also send at least one input Prompt to be displayed to and filled out by the user. Response should be set to the user's input, and will be sent back in the user authentication information response. EchoResponse is a server recommendation for whether or not the user's response should be echoed back during input.

Note: The server may send several prompts in a single packet. The component will fire the SSHKeyboardInteractive event once for each prompt.

SSHServerAuthentication Event (SSHReverseTunnel Component)

Fired after the server presents its public key to the client.

Syntax

• C#
• VB.NET

public event OnSSHServerAuthenticationHandler OnSSHServerAuthentication;

public delegate void OnSSHServerAuthenticationHandler(object sender, SSHReverseTunnelSSHServerAuthenticationEventArgs e);

public class SSHReverseTunnelSSHServerAuthenticationEventArgs : EventArgs {
  public string HostKey { get; }
  public byte[] HostKeyB { get; }
  public string Fingerprint { get; }
  public string KeyAlgorithm { get; }
  public string CertSubject { get; }
  public string CertIssuer { get; }
  public string Status { get; }
  public bool Accept { get; set; }
}

Public Event OnSSHServerAuthentication As OnSSHServerAuthenticationHandler

Public Delegate Sub OnSSHServerAuthenticationHandler(sender As Object, e As SSHReverseTunnelSSHServerAuthenticationEventArgs)

Public Class SSHReverseTunnelSSHServerAuthenticationEventArgs Inherits EventArgs
  Public ReadOnly Property HostKey As String
  Public ReadOnly Property HostKeyB As Byte()
  Public ReadOnly Property Fingerprint As String
  Public ReadOnly Property KeyAlgorithm As String
  Public ReadOnly Property CertSubject As String
  Public ReadOnly Property CertIssuer As String
  Public ReadOnly Property Status As String
  Public Property Accept As Boolean
End Class

Remarks

This event is fired when the client can decide whether or not to continue with the connection process. If the public key is known to be a valid key for the Secure Shell (SSH) server, Accept should be set to True within the event. Otherwise, the server will not be authenticated and the connection will be broken.

Accept will be True only if either HostKey or Fingerprint is identical to the value of SSHAcceptServerHostKey.

Accept may be set to True manually to accept the server host key.

Note: SSH's security inherently relies on client verification of the host key. Ignoring the host key and always setting Accept to True is strongly discouraged, and could cause potentially serious security vulnerabilities in your application. It is recommended that clients maintain a list of known keys for each server and check HostKey against this list each time a connection is attempted.

Host Key contains the full binary text of the key, in the same format used internally by SSH.

Fingerprint holds the SHA-256 hash of HostKey in the hex-encoded form: 0a:1b:2c:3d. To configure the hash algorithm used to calculate this value, see SSHFingerprintHashAlgorithm.

KeyAlgorithm identifies the host key algorithm. The following values are supported:

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

CertSubject is the subject of the certificate. This is applicable only when KeyAlgorithm is "x509v3-sign-rsa" or "x509v3-sign-dss".

CertIssuer is the issuer of the certificate. This is applicable only when KeyAlgorithm is "x509v3-sign-rsa" or "x509v3-sign-dss".

Status is reserved for future use.

SSHStatus Event (SSHReverseTunnel Component)

Fired to track the progress of the secure connection.

Syntax

• C#
• VB.NET

public event OnSSHStatusHandler OnSSHStatus;

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

public class SSHReverseTunnelSSHStatusEventArgs : EventArgs {
  public string Message { get; }
}

Public Event OnSSHStatus As OnSSHStatusHandler

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

Public Class SSHReverseTunnelSSHStatusEventArgs Inherits EventArgs
  Public ReadOnly Property Message As String
End Class

Remarks

The event is fired for informational and logging purposes only. Used to track the progress of the connection.

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

• C#
• VB.NET

public Certificate();

Public Certificate()

• C#
• VB.NET

public Certificate(string certificateFile);

Public Certificate(ByVal CertificateFile As String)

• C#
• VB.NET

public Certificate(byte[] encoded);

Public Certificate(ByVal Encoded As Byte())

• C#
• VB.NET

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)

• C#
• VB.NET

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)

• C#
• VB.NET

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())

• C#
• VB.NET

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)

• C#
• VB.NET

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)

• C#
• VB.NET

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())

Firewall Type

The firewall the component will connect through.

Remarks

When connecting through a firewall, this type is used to specify different properties of the firewall, such as the firewall Host and the FirewallType.

Fields

Constructors

• C#
• VB.NET

public Firewall();

Public Firewall()

SSHRTChannel Type

A currently open Secure Shell (SSH) channel.

Remarks

This type holds details about currently open channels. Each time a client connects to the reverse tunnel a new channel of this type is added to Channels.

Fields

Config Settings (SSHReverseTunnel Component)

SSHReverseTunnel Config Settings

SSHClient Config Settings

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

TCPClient Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (SSHReverseTunnel Component)

SSHReverseTunnel Errors

SSHClient Errors

The component may also return one of the following error codes, which are inherited from other components.

TCPClient Errors

TCP/IP Errors