SSHReverseTunnel Class

Properties   Methods   Events   Config Settings   Errors  

The SSHReverseTunnel class provides a simple way to establish a reverse tunnel with an SSH host.

Syntax

ipworksssh.Sshreversetunnel

Remarks

The SSHReverseTunnel class may be used to establish a reverse tunnel with an SSH host. The SSH host will listen for incoming connections on the specified port and forward traffic to the class through the SSH tunnel.

The SSHHost and SSHPort properties specify the SSH server to use. The SSHUser and SSHPassword properties allow the client to authenticate itself with the server. The SSHServerAuthentication event and/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 connection to 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 class 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 class over the tunnel causes the events of the class 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 class. In the above code, the last two parameters are empty and 0, indicating to the class that no local forwarding is requested.

Once RequestForwarding returns, the SSH reverse tunnel is established. Any connection made to the SSH host on the specified port will then trigger the class'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 is 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 class is automatically forwarded to a separate endpoint. This allows the class 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 class 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.

Additional Notes

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 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 (SSHReverseTunnel Class)

A collection of currently open channels.

Syntax

public SSHRTChannelMap getChannels();

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 where the channel's Id string is used as the key to the desired SSH channel object.

Example (Sending Data to a Channel)

channels.item("1").setDataToSend("channel specific data");

This property is read-only.

Connected Property (SSHReverseTunnel Class)

This shows whether the class is connected.

Syntax

public boolean isConnected();


public void setConnected(boolean connected);

Default Value

False

Remarks

This property is used to determine whether or not the class is connected to the remote host.

Note: It is recommended to use the Connect or Disconnect method instead of setting this property.

This property is not available at design time.

Firewall Property (SSHReverseTunnel Class)

A set of properties related to firewall access.

Syntax

public Firewall getFirewall();


public void setFirewall(Firewall firewall);

Remarks

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

LocalHost Property (SSHReverseTunnel 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

The LocalHost 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 multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface.

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 multi-homed 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 Class)

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

Syntax

public int getLocalPort();


public void setLocalPort(int localPort);

Default Value

0

Remarks

This property must be set before a connection is attempted. It instructs the class 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 in the client side.

SSHAcceptServerHostKey Property (SSHReverseTunnel Class)

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

Syntax

public Certificate getSSHAcceptServerHostKey();


public void setSSHAcceptServerHostKey(Certificate SSHAcceptServerHostKey);

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 Class)

The authentication method to be used the class when calling SSHLogon .

Syntax

public int getSSHAuthMode();


public void setSSHAuthMode(int SSHAuthMode);


Enumerated values:
  public final static int amNone = 0;
  public final static int amMultiFactor = 1;
  public final static int amPassword = 2;
  public final static int amPublicKey = 3;
  public final static int amKeyboardInteractive = 4;
  public final static int amGSSAPIWithMic = 5;
  public final static int amCustom = 6;
  public final static int amGSSAPIKeyex = 7;

Default Value

2

Remarks

The 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 class 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 class 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 class supports the following authentication methods:

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

SSHCert Property (SSHReverseTunnel Class)

A certificate to be used for authenticating the SSHUser .

Syntax

public Certificate getSSHCert();


public void setSSHCert(Certificate SSHCert);

Remarks

In order 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 will attempt to use those values to verify the signature.

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

SSHCompressionAlgorithms Property (SSHReverseTunnel Class)

A comma-separated list containing all allowable compression algorithms.

Syntax

public String getSSHCompressionAlgorithms();


public void setSSHCompressionAlgorithms(String SSHCompressionAlgorithms);

Default Value

"none,zlib"

Remarks

During the 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, so it is important to list multiple algorithms in preferential order. If no algorithm can be agreed upon, 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 (SSHReverseTunnel Class)

A 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,aes256-cbc,aes192-cbc,aes128-cbc,3des-ctr,3des-cbc,blowfish-cbc,arcfour256,arcfour128,arcfour,cast128-cbc,aes256-gcm@openssh.com,aes128-gcm@openssh.com,chacha20-poly1305@openssh.com"

Remarks

During the 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, so it is important to list multiple algorithms in preferential order. If no algorithm can be agreed upon, 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:

SSHHost Property (SSHReverseTunnel Class)

The address of the SSH host.

Syntax

public String getSSHHost();


public void setSSHHost(String SSHHost);

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 Class)

The password for SSH password-based authentication.

Syntax

public String getSSHPassword();


public void setSSHPassword(String SSHPassword);

Default Value

""

Remarks

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

SSHPort Property (SSHReverseTunnel Class)

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

Syntax

public int getSSHPort();


public void setSSHPort(int SSHPort);

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 Class)

The username for SSH authentication.

Syntax

public String getSSHUser();


public void setSSHUser(String SSHUser);

Default Value

""

Remarks

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

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

Timeout Property (SSHReverseTunnel Class)

A timeout for the class.

Syntax

public int getTimeout();


public void setTimeout(int timeout);

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 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.

Please note that by default, all timeouts are inactivity timeouts, i.e. 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 Class)

Requests the server to stop forwarding a remote TCP/IP port.

Syntax

public void cancelForwarding(String address, int port);

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 Class)

Closes a existing SSHChannel .

Syntax

public void closeChannel(String channelId);

Remarks

ChannelId is the identifier for the SSH channel to be closed.

Config Method (Sshreversetunnel 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.

DecodePacket Method (Sshreversetunnel Class)

Decodes a hex-encoded SSH packet.

Syntax

public byte[] decodePacket(String encodedPacket);

Remarks

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

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

DoEvents Method (Sshreversetunnel Class)

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.

EncodePacket Method (Sshreversetunnel Class)

Hex encodes an SSH packet.

Syntax

public String encodePacket(byte[] packet);

Remarks

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

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

ExchangeKeys Method (Sshreversetunnel Class)

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

Syntax

public void exchangeKeys();

Remarks

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. This makes it more difficult to break the security of data-intensive or long-lived connections.

GetSSHParam Method (Sshreversetunnel Class)

Used to read a field from an 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 upon 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

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 only applicable for reading and creating SSH packets for use within the SSHCustomAuth event.

GetSSHParamBytes Method (Sshreversetunnel Class)

Used to read a field from an SSH packet's payload.

Syntax

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

Remarks

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

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

RequestForwarding Method (Sshreversetunnel Class)

Requests the server to forward a remote TCP/IP port.

Syntax

public void requestForwarding(String address, int port, String forwardingHost, int forwardingPort);

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 SSH channels to the class.

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 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 class 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 class over the tunnel causes the events of the class 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 class. In the above code, the last two parameters are empty and 0, indicating to the class that no local forwarding is requested.

Once RequestForwarding returns, the SSH reverse tunnel is established. Any connection made to the SSH host on the specified port will then trigger the class'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 is 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 class is automatically forwarded to a separate endpoint. This allows the class 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 class 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 Class)

Reset the class.

Syntax

public void reset();

Remarks

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

SendChannelData Method (Sshreversetunnel Class)

Used to send data over an 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.

SetSSHParam Method (Sshreversetunnel Class)

Used to write 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 an 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 encoded in hexadecimal by prefixing "0x" to the beginning of the string, otherwise the value is assumed to be base-10.

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

SSHLogoff Method (Sshreversetunnel Class)

Logoff from the SSH server.

Syntax

public void SSHLogoff();

Remarks

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

SSHLogon Method (Sshreversetunnel Class)

Logon to the SSHHost using the current SSHUser and SSHPassword .

Syntax

public void SSHLogon(String SSHHost, int SSHPort);

Remarks

Logon to the 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 Class)

This event is fired immediately after a connection completes (or fails).

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void connected(SshreversetunnelConnectedEvent e) {}
  ...
}

public class SshreversetunnelConnectedEvent {
  public int statusCode;
  public String description;
}

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 Class)

This event is fired to indicate changes in the connection state.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void connectionStatus(SshreversetunnelConnectionStatusEvent e) {}
  ...
}

public class SshreversetunnelConnectionStatusEvent {
  public String connectionEvent;
  public int statusCode;
  public String description;
}

Remarks

The ConnectionStatus 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 Class)

This event is fired when a connection is closed.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void disconnected(SshreversetunnelDisconnectedEvent e) {}
  ...
}

public class SshreversetunnelDisconnectedEvent {
  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 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 Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void error(SshreversetunnelErrorEvent e) {}
  ...
}

public class SshreversetunnelErrorEvent {
  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.

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 class 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 Class)

Fires once for each log message.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void log(SshreversetunnelLogEvent e) {}
  ...
}

public class SshreversetunnelLogEvent {
  public int logLevel;
  public String message;
  public String logType;
}

Remarks

This event fires once for each log messages generated by the class. The verbosity is controlled by the LogLevel setting.

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

Message is the log message.

LogType is reserved for future use.

ReconnectAttempt Event (Sshreversetunnel Class)

Fires when attempting to reconnect.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void reconnectAttempt(SshreversetunnelReconnectAttemptEvent e) {}
  ...
}

public class SshreversetunnelReconnectAttemptEvent {
  public String host;
  public int port;
  public int retryCount;
  public int retriesRemaining;
  public int maxRetryCount;
  public int retryInterval;
  public int retryType;
  public int remoteListeningPort;
  public boolean cancel;
}

Remarks

This event fires both when attempting to reconnect to the SSHHost and when re-establishing a SSH tunnel.

Only applicable 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 Class)

Fired when a channel is closed.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHChannelClosed(SshreversetunnelSSHChannelClosedEvent e) {}
  ...
}

public class SshreversetunnelSSHChannelClosedEvent {
  public String channelId;
}

Remarks

The SSHChannelClosed event is fired when a channel is closed on an SSH connection.

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

SSHChannelData Event (Sshreversetunnel Class)

Fired when the SSHHost sends channel data to the client.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHChannelData(SshreversetunnelSSHChannelDataEvent e) {}
  ...
}

public class SshreversetunnelSSHChannelDataEvent {
  public String channelId;
  public byte[] channelData;
}

Remarks

The SSHChannelData event will fire as data is received for the given ChannelId. ChannelData will contain the decrypted contents of the SSH packet.

SSHChannelEOF Event (Sshreversetunnel Class)

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

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHChannelEOF(SshreversetunnelSSHChannelEOFEvent e) {}
  ...
}

public class SshreversetunnelSSHChannelEOFEvent {
  public String channelId;
}

Remarks

The SSHChannelEOF event is fired when the end of the data stream for a channel on an SSH connection is reached.

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

SSHChannelOpened Event (Sshreversetunnel Class)

Fired when a channel is successfully opened.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHChannelOpened(SshreversetunnelSSHChannelOpenedEvent e) {}
  ...
}

public class SshreversetunnelSSHChannelOpenedEvent {
  public String channelId;
}

Remarks

The SSHChannelOpened event is fired when a channel is successfully opened on an SSH connection.

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

SSHChannelOpenRequest Event (Sshreversetunnel Class)

Fired when the peer attempts to open a new channel.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHChannelOpenRequest(SshreversetunnelSSHChannelOpenRequestEvent e) {}
  ...
}

public class SshreversetunnelSSHChannelOpenRequestEvent {
  public String channelId;
  public String service;
  public String connectedAddress;
  public int connectedPort;
  public String originAddress;
  public int originPort;
  public boolean accept;
}

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 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 Class)

Fired when the class is ready to send data.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHChannelReadyToSend(SshreversetunnelSSHChannelReadyToSendEvent e) {}
  ...
}

public class SshreversetunnelSSHChannelReadyToSendEvent {
  public String channelId;
}

Remarks

This event fires when data can be sent over the SSH Channel specified by ChannelId.

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 (Sshreversetunnel Class)

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

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHChannelRequest(SshreversetunnelSSHChannelRequestEvent e) {}
  ...
}

public class SshreversetunnelSSHChannelRequestEvent {
  public String channelId;
  public String requestType;
  public byte[] packet;
  public boolean success;
}

Remarks

The SSHHost may send requests that affect the status of a particular SSHChannel. Some requests will be automatically handled by the class. However, others 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 are dependent upon 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 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 SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHChannelRequested Event (Sshreversetunnel Class)

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

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHChannelRequested(SshreversetunnelSSHChannelRequestedEvent e) {}
  ...
}

public class SshreversetunnelSSHChannelRequestedEvent {
  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. However, others 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 are dependent upon 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 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 SSH data until the event returns. In order to prevent this from happening, all requests should be processed asynchronously in a separate thread outside of this event.

SSHCustomAuth Event (Sshreversetunnel Class)

Fired when the class is doing custom authentication.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHCustomAuth(SshreversetunnelSSHCustomAuthEvent e) {}
  ...
}

public class SshreversetunnelSSHCustomAuthEvent {
  public String packet;
}

Remarks

SSHCustomAuth is fired during the user authentication stage of the SSH logon process if SSHAuthMode is set to amCustom. Packet contains the raw last 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 Class)

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

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHKeyboardInteractive(SshreversetunnelSSHKeyboardInteractiveEvent e) {}
  ...
}

public class SshreversetunnelSSHKeyboardInteractiveEvent {
  public String name;
  public String instructions;
  public String prompt;
  public String response;
  public boolean echoResponse;
}

Remarks

SSHKeyboardInteractive is fired during the user authentication stage of the SSH logon process. During authentication, the class will request a list of available authentication methods for the SSHUser. For example, if the SSHHost responds with "keyboard-interactive", the class 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 class will fire the SSHKeyboardInteractive event once for each prompt.

SSHServerAuthentication Event (Sshreversetunnel Class)

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

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHServerAuthentication(SshreversetunnelSSHServerAuthenticationEvent e) {}
  ...
}

public class SshreversetunnelSSHServerAuthenticationEvent {
  public byte[] hostKey;
  public String fingerprint;
  public String keyAlgorithm;
  public String certSubject;
  public String certIssuer;
  public String status;
  public boolean accept;
}

Remarks

This event is where the client can decide whether to continue with the connection process or not. If the public key is known to be a valid key for the 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 that 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. Supported values are:

• 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 only applicable when KeyAlgorithm is "x509v3-sign-rsa" or "x509v3-sign-dss".

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

Status is reserved for future use.

SSHStatus Event (Sshreversetunnel Class)

Shows the progress of the secure connection.

Syntax

public class DefaultSshreversetunnelEventListener implements SshreversetunnelEventListener {
  ...
  public void SSHStatus(SshreversetunnelSSHStatusEvent e) {}
  ...
}

public class SshreversetunnelSSHStatusEvent {
  public String message;
}

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

public Certificate();

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

public Certificate( certificateFile);

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

public Certificate( certificateData);

Parses CertificateData as an X.509 public key.

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

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store. After the store has been successfully opened, the class will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X.509 certificate's subject Distinguished Name (DN).

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

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store. ConfigurationString is a newline separated list of name-value pairs that may be used to modify the default behavior. Possible values include "PersistPFXKey", which shows whether or not the PFX key is persisted after performing operations with the private key. This correlates to the PKCS12_NO_PERSIST_KEY CryptoAPI option. The default value is True (the key is persisted). "Thumbprint" - an MD5, SHA-1, or SHA-256 thumbprint of the certificate to load. When specified, this value is used to select the certificate in the store. This is applicable to cstUser, cstMachine, cstPublicKeyFile, and cstPFXFile store types. "UseInternalSecurityAPI" shows whether the platform (default) or the internal security API is used when performing certificate-related operations. After the store has been successfully opened, the class will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X.509 certificate's subject Distinguished Name (DN).

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

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a file containing the certificate store. StorePassword is the password used to protect the store. After the store has been successfully opened, the class will load Encoded as an X.509 certificate and search the opened store for a corresponding private key.

public Certificate( certStoreType,  storeBlob,  storePassword,  subject);

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. StoreBlob is a string (binary- or Base64-encoded) containing the certificate data. StorePassword is the password used to protect the store. After the store has been successfully opened, the class will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X.509 certificate's subject Distinguished Name (DN).

public Certificate( certStoreType,  storeBlob,  storePassword,  subject,  configurationString);

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. StoreBlob is a string (binary- or Base64-encoded) containing the certificate data. StorePassword is the password used to protect the store. After the store has been successfully opened, the class will attempt to find the certificate identified by Subject . This can be either a complete or a substring match of the X.509 certificate's subject Distinguished Name (DN).

public Certificate( certStoreType,  storeBlob,  storePassword,  encoded);

CertStoreType identifies the type of certificate store to use. See StoreType for descriptions of the different certificate stores. Store is a string (binary- or Base64-encoded) containing the certificate store. StorePassword is the password used to protect the store. After the store has been successfully opened, the class will load Encoded as an X.509 certificate and search the opened store for a corresponding private key.

Firewall Type

The firewall the class 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

public Firewall();

SSHRTChannel Type

A currently open 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 Class)

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 Class)

SSHReverseTunnel Errors

SSHClient Errors

TCPClient Errors

TCP/IP Errors