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IPWorks SSH 2022 Delphi Edition

Version 22.0 [Build 8172]

SSHReverseTunnel Component

Properties   Methods   Events   Configuration Settings   Errors  

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

Syntax

TiphSSHReverseTunnel

Remarks

The SSHReverseTunnel component may be used to establish a reverse tunnel with a 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 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 has been successfully established. To establish a reverse tunnel call RequestForwarding. 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 request 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 or 0 indicating to the component that no local forwarding is requested.

Once RequestForwarding returns the SSH reverse tunnel is established and any connection made to the SSH host on the specified port will trigger events of the component 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 e.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. To send data over the channel call the SendChannelData method. To close the channel call the CloseChannel method.

Local Forwarding

In this mode the 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 request from port 777 on SSHHost. The component is instructed to establish a connection to "nsoftware.com" on port 80 when a client connect 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:

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.

ChannelsA collection of currently open channels.
ConnectedShows whether the component is connected.
FirewallA set of properties related to firewall access.
LocalHostThe name of the local host or user-assigned IP interface through which connections are initiated or accepted.
LocalPortThe TCP port in the local host where the component binds.
SSHAcceptServerHostKeyEncodedThis is the certificate (PEM/base64 encoded).
SSHAuthModeThe authentication method to be used the component when calling SSHLogon .
SSHCertEncodedThis is the certificate (PEM/base64 encoded).
SSHCertStoreThis is the name of the certificate store for the client certificate.
SSHCertStorePasswordIf the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.
SSHCertStoreTypeThis is the type of certificate store for this certificate.
SSHCertSubjectThis is the subject of the certificate used for client authentication.
SSHCompressionAlgorithmsA comma-separated list containing all allowable compression algorithms.
SSHEncryptionAlgorithmsA comma-separated list containing all allowable encryption algorithms.
SSHHostThe address of the SSH host.
SSHPasswordThe password for SSH password-based authentication.
SSHPortThe port on the SSH server where the SSH service is running; by default, 22.
SSHUserThe username for SSH authentication.
TimeoutA timeout for the component.

Method List


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

CancelForwardingRequests the server to stop forwarding a remote TCP/IP port.
CloseChannelCloses a existing SSHChannel .
ConfigSets or retrieves a configuration setting.
DecodePacketDecodes a hex-encoded SSH packet.
DoEventsProcesses events from the internal message queue.
EncodePacketHex encodes an SSH packet.
ExchangeKeysCauses the component to exchange a new set of session keys with the SSHHost .
GetSSHParamUsed to read a field from an SSH packet's payload.
GetSSHParamBytesUsed to read a field from an SSH packet's payload.
RequestForwardingRequests the server to forward a remote TCP/IP port.
ResetReset the component.
SendChannelDataUsed to send data over an SSH channel.
SetSSHParamUsed to write a field to the end of a payload.
SSHLogoffLogoff from the SSH server.
SSHLogonLogon to the SSHHost using the current SSHUser and SSHPassword .

Event List


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

ConnectedFired immediately after a connection completes (or fails).
ConnectionStatusFired to indicate changes in connection state.
DisconnectedFired when a connection is closed.
ErrorInformation about errors during data delivery.
LogFires once for each log message.
ReconnectAttemptFires when attempting to reconnect.
SSHChannelClosedFired when a channel is closed.
SSHChannelDataFired when the SSHHost sends channel data to the client.
SSHChannelEOFFired when the remote peer signals the end of the data stream for the channel.
SSHChannelOpenedFired when a channel is successfully opened.
SSHChannelOpenRequestFired when the peer attempts to open a new channel.
SSHChannelReadyToSendFired when the component is ready to send data.
SSHChannelRequestFired when the SSHHost sends a channel request to the client.
SSHChannelRequestedFired if the SSHChannelRequest was successful, any further processing for the channel request should be done here.
SSHCustomAuthFired when the component is doing custom authentication.
SSHKeyboardInteractiveFired when the component receives a request for user input from the server.
SSHServerAuthenticationFired after the server presents its public key to the client.
SSHStatusShows the progress of the secure connection.

Configuration Settings


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

AutoReconnectWhether to automatically reestablish the SSH connection.
DefaultChannelIdleTimeoutThe inactivity timeout for channels.
ForwardedPortThe remote port which is forwarded.
ForwardingLocalHostThe interface on which to bind when forwarding data.
MaxRetryCountThe maximum number of retries when reconnecting.
RetryIntervalThe interval in seconds between reconnect attempts.
ClientSSHVersionStringThe SSH version string used by the component.
EnablePageantAuthWhether to use a key stored in Pageant to perform client authentication.
KerberosDelegationIf true, asks for credentials with delegation enabled during authentication.
KerberosRealmThe fully qualified domain name of the Kerberos Realm to use for GSSAPI authentication.
KerberosSPNThe Kerberos Service Principal Name of the SSH host.
KeyRenegotiationThresholdSets the threshold for the SSH Key Renegotiation.
LogLevelSpecifies the level of detail that is logged.
MaxPacketSizeThe maximum packet size of the channel, in bytes.
MaxWindowSizeThe maximum window size allowed for the channel, in bytes.
PasswordPromptThe text of the password prompt used in keyboard-interactive authentication.
PreferredDHGroupBitsThe size (in bits) of the preferred modulus (p) to request from the server.
RecordLengthThe length of received data records.
ServerSSHVersionStringThe remote host's SSH version string.
SignedSSHCertThe CA signed client public key used when authenticating.
SSHAcceptAnyServerHostKeyIf set the component will accept any key presented by the server.
SSHAcceptServerCAKeyThe CA public key that signed the server's host key.
SSHAcceptServerHostKeyFingerPrintThe fingerprint of the server key to accept.
SSHFingerprintHashAlgorithmThe algorithm used to calculate the fingerprint.
SSHFingerprintMD5The server hostkey's MD5 fingerprint.
SSHFingerprintSHA1The server hostkey's SHA1 fingerprint.
SSHFingerprintSHA256The server hostkey's SHA256 fingerprint.
SSHKeepAliveCountMaxThe maximum number of keep alive packets to send without a response.
SSHKeepAliveIntervalThe interval between keep alive packets.
SSHKeyExchangeAlgorithmsSpecifies the supported key exchange algorithms.
SSHKeyRenegotiateCauses the component to renegotiate the SSH keys.
SSHMacAlgorithmsSpecifies the supported Mac algorithms.
SSHPubKeyAuthSigAlgorithmsSpecifies the signature algorithm when attempting public key authentication.
SSHPublicKeyAlgorithmsSpecifies the supported public key algorithms.
SSHVersionPatternThe pattern used to match the remote host's version string.
TryAllAvailableAuthMethodsIf set to true, the component will try all available authentication methods.
WaitForChannelCloseWhether to wait for channels to be closed before disconnected.
WaitForServerDisconnectWhether to wait for the server to close the connection.
CloseStreamAfterTransferIf true, the component will close the upload or download stream after the transfer.
ConnectionTimeoutSets a separate timeout value for establishing a connection.
FirewallAutoDetectTells the component whether or not to automatically detect and use firewall system settings, if available.
FirewallHostName or IP address of firewall (optional).
FirewallPasswordPassword to be used if authentication is to be used when connecting through the firewall.
FirewallPortThe TCP port for the FirewallHost;.
FirewallTypeDetermines the type of firewall to connect through.
FirewallUserA user name if authentication is to be used connecting through a firewall.
KeepAliveIntervalThe retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.
KeepAliveTimeThe inactivity time in milliseconds before a TCP keep-alive packet is sent.
LingerWhen set to True, connections are terminated gracefully.
LingerTimeTime in seconds to have the connection linger.
LocalHostThe name of the local host through which connections are initiated or accepted.
LocalPortThe port in the local host where the component binds.
MaxLineLengthThe maximum amount of data to accumulate when no EOL is found.
MaxTransferRateThe transfer rate limit in bytes per second.
ProxyExceptionsListA semicolon separated list of hosts and IPs to bypass when using a proxy.
TCPKeepAliveDetermines whether or not the keep alive socket option is enabled.
TcpNoDelayWhether or not to delay when sending packets.
UseIPv6Whether to use IPv6.
AbsoluteTimeoutDetermines whether timeouts are inactivity timeouts or absolute timeouts.
FirewallDataUsed to send extra data to the firewall.
InBufferSizeThe size in bytes of the incoming queue of the socket.
OutBufferSizeThe size in bytes of the outgoing queue of the socket.
BuildInfoInformation about the product's build.
CodePageThe system code page used for Unicode to Multibyte translations.
LicenseInfoInformation about the current license.
UseInternalSecurityAPITells the component whether or not to use the system security libraries or an internal implementation.

Channels Property (SSHReverseTunnel Component)

A collection of currently open channels.

Syntax

property Channels: TiphSSHRTChannelList read get_Channels;

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)

This property is read-only.

Connected Property (SSHReverseTunnel Component)

Shows whether the component is connected.

Syntax

property Connected: Boolean read get_Connected write set_Connected;

Default Value

false

Remarks

This property is used to determine whether or not the component 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 Component)

A set of properties related to firewall access.

Syntax

property Firewall: TiphFirewall read get_Firewall write set_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

property LocalHost: String read get_LocalHost write set_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 component initiate connections (or accept in the case of server components) only through that interface.

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 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 Component)

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

Syntax

property LocalPort: Integer read get_LocalPort write set_LocalPort;

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 in the client side.

SSHAcceptServerHostKeyEncoded Property (SSHReverseTunnel Component)

This is the certificate (PEM/base64 encoded).

Syntax

property SSHAcceptServerHostKeyEncoded: String read get_SSHAcceptServerHostKeyEncoded write set_SSHAcceptServerHostKeyEncoded;
property SSHAcceptServerHostKeyEncodedB: TBytes read get_SSHAcceptServerHostKeyEncodedB write set_SSHAcceptServerHostKeyEncodedB;

Default Value

''

Remarks

This is the certificate (PEM/base64 encoded). This property is used to assign a specific certificate. The Store and Subject properties also may be used to specify a certificate.

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

This property is not available at design time.

SSHAuthMode Property (SSHReverseTunnel Component)

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

Syntax

property SSHAuthMode: TiphTSSHAuthModes read get_SSHAuthMode write set_SSHAuthMode;
TiphTSSHAuthModes = ( amNone, amMultiFactor, amPassword, amPublicKey, amKeyboardInteractive, amGSSAPIWithMic, amCustom );

Default Value

amPassword

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 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:

amNone (0)No authentication will be performed. The current SSHUser value is ignored, and the connection will be logged in as anonymous.
amMultiFactor (1)This allows the component to attempt a multi-step authentication process. The component will send authentication data to the server based on the list of methods allowed for the current user and the authentication property values supplied. The component will continue to send authentication data until the server acknowledges authentication success. If the server rejects an authentication step, the component raises an exception.
amPassword (2)The component will use the values of SSHUser and SSHPassword to authenticate the user.
amPublicKey (3)The component will use the values of SSHUser and the SSHCert* properties to authenticate the user. the SSHCert* properties must have a private key available for this authentication method to succeed.
amKeyboardInteractive (4)At the time of authentication, the component will fire the SSHKeyboardInteractive event containing instructions on how to complete the authentication step. (NOTE: amKeyboardInteractive is not supported in SSHTunnel).
amGSSAPIWithMic (5)This allows the component to attempt Kerberos authentication using the GSSAPI-WITH-MIC scheme. The client will try Kerberos authentication using the value of SSHUser (single sign-on), or if SSHPassword is specified as well, it will try Kerberos authentication with alternate credentials. This is currently supported only in the .NET client.
amCustom (6)This allows the component caller to take over the authentication process completely. When amCustom is set, the component will fire the SSHCustomAuth event as necessary to complete the authentication process.

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.SSHCertStoreType = SSHCertStoreTypes.cstPFXFile; Control.SSHCertStore = "cert.pfx"; Control.SSHCertStorePassword = "certpassword"; Control.SSHCertSubject = "*"; Control.SSHLogon("server", 22)

SSHCertEncoded Property (SSHReverseTunnel Component)

This is the certificate (PEM/base64 encoded).

Syntax

property SSHCertEncoded: String read get_SSHCertEncoded write set_SSHCertEncoded;
property SSHCertEncodedB: TBytes read get_SSHCertEncodedB write set_SSHCertEncodedB;

Default Value

''

Remarks

This is the certificate (PEM/base64 encoded). This property is used to assign a specific certificate. The Store and Subject properties also may be used to specify a certificate.

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

This property is not available at design time.

SSHCertStore Property (SSHReverseTunnel Component)

This is the name of the certificate store for the client certificate.

Syntax

property SSHCertStore: String read get_SSHCertStore write set_SSHCertStore;
property SSHCertStoreB: TBytes read get_SSHCertStoreB write set_SSHCertStoreB;

Default Value

'MY'

Remarks

This is the name of the certificate store for the client certificate.

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

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

Designations of certificate stores are platform-dependent.

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

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

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e. PKCS12 certificate store).

SSHCertStorePassword Property (SSHReverseTunnel Component)

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

Syntax

property SSHCertStorePassword: String read get_SSHCertStorePassword write set_SSHCertStorePassword;

Default Value

''

Remarks

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

SSHCertStoreType Property (SSHReverseTunnel Component)

This is the type of certificate store for this certificate.

Syntax

property SSHCertStoreType: TiphCertStoreTypes read get_SSHCertStoreType write set_SSHCertStoreType;
TiphCertStoreTypes = ( cstUser, cstMachine, cstPFXFile, cstPFXBlob, cstJKSFile, cstJKSBlob, cstPEMKeyFile, cstPEMKeyBlob, cstPublicKeyFile, cstPublicKeyBlob, cstSSHPublicKeyBlob, cstP7BFile, cstP7BBlob, cstSSHPublicKeyFile, cstPPKFile, cstPPKBlob, cstXMLFile, cstXMLBlob, cstJWKFile, cstJWKBlob, cstSecurityKey, cstBCFKSFile, cstBCFKSBlob, cstAuto );

Default Value

cstUser

Remarks

This is the type of certificate store for this certificate.

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

0 (cstUser - default)For Windows, this specifies that the certificate store is a certificate store owned by the current user. Note: this store type is not available in Java.
1 (cstMachine)For Windows, this specifies that the certificate store is a machine store. Note: this store type is not available in Java.
2 (cstPFXFile)The certificate store is the name of a PFX (PKCS12) file containing certificates.
3 (cstPFXBlob)The certificate store is a string (binary or base64-encoded) representing a certificate store in PFX (PKCS12) format.
4 (cstJKSFile)The certificate store is the name of a Java Key Store (JKS) file containing certificates. Note: this store type is only available in Java.
5 (cstJKSBlob)The certificate store is a string (binary or base64-encoded) representing a certificate store in Java Key Store (JKS) format. Note: this store type is only available in Java.
6 (cstPEMKeyFile)The certificate store is the name of a PEM-encoded file that contains a private key and an optional certificate.
7 (cstPEMKeyBlob)The certificate store is a string (binary or base64-encoded) that contains a private key and an optional certificate.
8 (cstPublicKeyFile)The certificate store is the name of a file that contains a PEM- or DER-encoded public key certificate.
9 (cstPublicKeyBlob)The certificate store is a string (binary or base64-encoded) that contains a PEM- or DER-encoded public key certificate.
10 (cstSSHPublicKeyBlob)The certificate store is a string (binary or base64-encoded) that contains an SSH-style public key.
11 (cstP7BFile)The certificate store is the name of a PKCS7 file containing certificates.
12 (cstP7BBlob)The certificate store is a string (binary) representing a certificate store in PKCS7 format.
13 (cstSSHPublicKeyFile)The certificate store is the name of a file that contains an SSH-style public key.
14 (cstPPKFile)The certificate store is the name of a file that contains a PPK (PuTTY Private Key).
15 (cstPPKBlob)The certificate store is a string (binary) that contains a PPK (PuTTY Private Key).
16 (cstXMLFile)The certificate store is the name of a file that contains a certificate in XML format.
17 (cstXMLBlob)The certificate store is a string that contains a certificate in XML format.
18 (cstJWKFile)The certificate store is the name of a file that contains a JWK (JSON Web Key).
19 (cstJWKBlob)The certificate store is a string that contains a JWK (JSON Web Key).
20 (cstSecurityKey)The certificate is present on a physical security key accessible via a PKCS11 interface.

To use a security key the necessary data must first be collected using the CertMgr component. The ListStoreCertificates method may be called after setting CertStoreType to cstSecurityKey, CertStorePassword to the PIN, and CertStore to the full path of the PKCS11 dll. The certificate information returned in the CertList event's CertEncoded parameter may be saved for later use.

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

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

21 (cstBCFKSFile)The certificate store is the name of a file that contains a BCFKS (Bouncy Castle FIPS Key Store). Note: this store type is only available in Java and .NET.
22 (cstBCFKSBlob)The certificate store is a string (binary or base64-encoded) representing a certificate store in BCFKS (Bouncy Castle FIPS Key Store) format. Note: this store type is only available in Java and .NET.
99 (cstAuto)The store type is automatically detected from the input data. This setting may be used with both public and private keys and can detect any of the supported formats automatically.

SSHCertSubject Property (SSHReverseTunnel Component)

This is the subject of the certificate used for client authentication.

Syntax

property SSHCertSubject: String read get_SSHCertSubject write set_SSHCertSubject;

Default Value

''

Remarks

This is the subject of the certificate used for client authentication.

This property must be set after all other certificate properites are set. When this property is set, a search is performed in the current certificate store certificate with matching subject.

If a matching certificate is found, the property is set to the full subject of the matching certificate.

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

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

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

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

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

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

SSHCompressionAlgorithms Property (SSHReverseTunnel Component)

A comma-separated list containing all allowable compression algorithms.

Syntax

property SSHCompressionAlgorithms: String read get_SSHCompressionAlgorithms write set_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 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)

A comma-separated list containing all allowable encryption algorithms.

Syntax

property SSHEncryptionAlgorithms: String read get_SSHEncryptionAlgorithms write set_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 component will raise an error and the connection will be aborted.

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

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

SSHHost Property (SSHReverseTunnel Component)

The address of the SSH host.

Syntax

property SSHHost: String read get_SSHHost write set_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 Component)

The password for SSH password-based authentication.

Syntax

property SSHPassword: String read get_SSHPassword write set_SSHPassword;

Default Value

''

Remarks

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

SSHPort Property (SSHReverseTunnel Component)

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

Syntax

property SSHPort: Integer read get_SSHPort write set_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 Component)

The username for SSH authentication.

Syntax

property SSHUser: String read get_SSHUser write set_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.SSHCertStoreType = SSHCertStoreTypes.cstPFXFile; Control.SSHCertStore = "cert.pfx"; Control.SSHCertStorePassword = "certpassword"; Control.SSHCertSubject = "*"; Control.SSHLogon("server", 22)

Timeout Property (SSHReverseTunnel Component)

A timeout for the component.

Syntax

property Timeout: Integer read get_Timeout write set_Timeout;

Default Value

60

Remarks

If the Timeout property is set to 0, all operations return immediately, potentially failing with a WOULDBLOCK error if data cannot be sent immediately.

If Timeout is set to a positive value, data is sent in a blocking manner and the component will wait for the operation to complete before returning control. The component will handle any potential WOULDBLOCK errors internally and automatically retry the operation for a maximum of Timeout seconds.

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 raises 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 Component)

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

Syntax

procedure CancelForwarding(Address: String; Port: Integer);

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

procedure CloseChannel(ChannelId: String);

Remarks

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

Config Method (SSHReverseTunnel Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): 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 SSH packet.

Syntax

function DecodePacket(EncodedPacket: String): TBytes;

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 Component)

Processes events from the internal message queue.

Syntax

procedure DoEvents();

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 an SSH packet.

Syntax

function EncodePacket(Packet: TBytes): String;

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 Component)

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

Syntax

procedure 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 Component)

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

Syntax

function GetSSHParam(Payload: TBytes; Field: String): String;

Remarks

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

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

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

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:

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

x11-req

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

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

env

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

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

exec

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

Command (string)The command to be executed.

subsystem

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

Subsystem (string)The name of the subsystem to be started (eg: "sftp").

xon-xoff

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

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

signal

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

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

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

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

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

GetSSHParamBytes Method (SSHReverseTunnel Component)

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

Syntax

function GetSSHParamBytes(Payload: TBytes; Field: String): TBytes;

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 Component)

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

Syntax

procedure RequestForwarding(Address: String; Port: Integer; ForwardingHost: String; ForwardingPort: Integer);

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 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 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 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 request 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 or 0 indicating to the component that no local forwarding is requested.

Once RequestForwarding returns the SSH reverse tunnel is established and any connection made to the SSH host on the specified port will trigger events of the component 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 e.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. To send data over the channel call the SendChannelData method. To close the channel call the CloseChannel method.

Local Forwarding

In this mode the 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 request from port 777 on SSHHost. The component is instructed to establish a connection to "nsoftware.com" on port 80 when a client connect 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)

Reset the component.

Syntax

procedure Reset();

Remarks

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

SendChannelData Method (SSHReverseTunnel Component)

Used to send data over an SSH channel.

Syntax

procedure SendChannelData(ChannelId: String; Data: TBytes);

Remarks

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

SetSSHParam Method (SSHReverseTunnel Component)

Used to write a field to the end of a payload.

Syntax

function SetSSHParam(Payload: TBytes; FieldType: String; FieldValue: String): TBytes;

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:

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

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 Component)

Logoff from the SSH server.

Syntax

procedure SSHLogoff();

Remarks

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

SSHLogon Method (SSHReverseTunnel Component)

Logon to the SSHHost using the current SSHUser and SSHPassword .

Syntax

procedure SSHLogon(SSHHost: String; SSHPort: Integer);

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 Component)

Fired immediately after a connection completes (or fails).

Syntax

type TConnectedEvent = procedure (
  Sender: TObject;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnConnected: TConnectedEvent read FOnConnected write FOnConnected;

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 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 connection state.

Syntax

type TConnectionStatusEvent = procedure (
  Sender: TObject;
  const ConnectionEvent: String;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnConnectionStatus: TConnectionStatusEvent read FOnConnectionStatus write FOnConnectionStatus;

Remarks

The ConnectionStatus event is fired when the connection state changes: completion of a firewall or proxy connection, completion of a security handshake, etc.

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

Firewall connection complete.
SSL or S/Shell handshake complete (where applicable).
Remote host connection complete.
Remote host disconnected.
SSL or S/Shell connection broken.
Firewall host disconnected.

StatusCode has the error code returned by the TCP/IP stack. Description contains a description of this code. The value of StatusCode is equal to the value of the error.

Disconnected Event (SSHReverseTunnel Component)

Fired when a connection is closed.

Syntax

type TDisconnectedEvent = procedure (
  Sender: TObject;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnDisconnected: TDisconnectedEvent read FOnDisconnected write FOnDisconnected;

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 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)

Information about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

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

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

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

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

Log Event (SSHReverseTunnel Component)

Fires once for each log message.

Syntax

type TLogEvent = procedure (
  Sender: TObject;
  LogLevel: Integer;
  const Message: String;
  const LogType: String
) of Object;

property OnLog: TLogEvent read FOnLog write FOnLog;

Remarks

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

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

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

Message is the log message.

LogType is reserved for future use.

ReconnectAttempt Event (SSHReverseTunnel Component)

Fires when attempting to reconnect.

Syntax

type TReconnectAttemptEvent = procedure (
  Sender: TObject;
  const Host: String;
  Port: Integer;
  RetryCount: Integer;
  RetriesRemaining: Integer;
  MaxRetryCount: Integer;
  RetryInterval: Integer;
  RetryType: Integer;
  RemoteListeningPort: Integer;
  var Cancel: Boolean
) of Object;

property OnReconnectAttempt: TReconnectAttemptEvent read FOnReconnectAttempt write FOnReconnectAttempt;

Remarks

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

This is only applicable when AutoReconnect is set to True. This event may fire both when establishing the SSH connection, and when establishing the SSH tunnel over the SSH connection. To determine which type of connection is being established check the RetryType parameter.

The following table provides details about the parameters.

Host Hold the SSH host to which the connection is attempted.
Port Is the Port on the SSH host to which the connection is attempted.
RetryCount Indicates the current retry attempt. For instance this may be retry 2 of 5, then RetryCount will hold the value 2.
RetriesRemaining The number of retries remaining after this attempt. This number does not include the current attempt. If MaxRetryCount is set to unlimited this will return -1.
MaxRetryCount The maximum number of retries as specified in MaxRetryCount.
RetryInterval The interval (in seconds) between retry attempts as specified in RetryInterval.
RetryType The type of connection being retried. Possible values are:
  • 0 - SSH
  • 1 - Reverse Tunnel
RemoteListeningPort The port on the SSH host which the reverse tunnel will use. This is only applicable when RetryType is 1 (Reverse Tunnel).
Cancel May be set within this event to cancel the retry attempts. If set to True no further retry attempts will be executed.

SSHChannelClosed Event (SSHReverseTunnel Component)

Fired when a channel is closed.

Syntax

type TSSHChannelClosedEvent = procedure (
  Sender: TObject;
  const ChannelId: String
) of Object;

property OnSSHChannelClosed: TSSHChannelClosedEvent read FOnSSHChannelClosed write FOnSSHChannelClosed;

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 Component)

Fired when the SSHHost sends channel data to the client.

Syntax

type TSSHChannelDataEvent = procedure (
  Sender: TObject;
  const ChannelId: String;
  ChannelData: String;
  ChannelDataB: TBytes
) of Object;

property OnSSHChannelData: TSSHChannelDataEvent read FOnSSHChannelData write FOnSSHChannelData;

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 Component)

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

Syntax

type TSSHChannelEOFEvent = procedure (
  Sender: TObject;
  const ChannelId: String
) of Object;

property OnSSHChannelEOF: TSSHChannelEOFEvent read FOnSSHChannelEOF write FOnSSHChannelEOF;

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 Component)

Fired when a channel is successfully opened.

Syntax

type TSSHChannelOpenedEvent = procedure (
  Sender: TObject;
  const ChannelId: String
) of Object;

property OnSSHChannelOpened: TSSHChannelOpenedEvent read FOnSSHChannelOpened write FOnSSHChannelOpened;

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 Component)

Fired when the peer attempts to open a new channel.

Syntax

type TSSHChannelOpenRequestEvent = procedure (
  Sender: TObject;
  const ChannelId: String;
  const Service: String;
  const ConnectedAddress: String;
  ConnectedPort: Integer;
  const OriginAddress: String;
  OriginPort: Integer;
  var Accept: Boolean
) of Object;

property OnSSHChannelOpenRequest: TSSHChannelOpenRequestEvent read FOnSSHChannelOpenRequest write FOnSSHChannelOpenRequest;

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 Component)

Fired when the component is ready to send data.

Syntax

type TSSHChannelReadyToSendEvent = procedure (
  Sender: TObject;
  const ChannelId: String
) of Object;

property OnSSHChannelReadyToSend: TSSHChannelReadyToSendEvent read FOnSSHChannelReadyToSend write FOnSSHChannelReadyToSend;

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 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

type TSSHChannelRequestEvent = procedure (
  Sender: TObject;
  const ChannelId: String;
  const RequestType: String;
  Packet: String;
  PacketB: TBytes;
  var Success: Boolean
) of Object;

property OnSSHChannelRequest: TSSHChannelRequestEvent read FOnSSHChannelRequest write FOnSSHChannelRequest;

Remarks

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

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

Syntax

type TSSHChannelRequestedEvent = procedure (
  Sender: TObject;
  const ChannelId: String;
  const RequestType: String;
  Packet: String;
  PacketB: TBytes
) of Object;

property OnSSHChannelRequested: TSSHChannelRequestedEvent read FOnSSHChannelRequested write FOnSSHChannelRequested;

Remarks

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

Fired when the component is doing custom authentication.

Syntax

type TSSHCustomAuthEvent = procedure (
  Sender: TObject;
  var Packet: String
) of Object;

property OnSSHCustomAuth: TSSHCustomAuthEvent read FOnSSHCustomAuth write FOnSSHCustomAuth;

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 Component)

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

Syntax

type TSSHKeyboardInteractiveEvent = procedure (
  Sender: TObject;
  const Name: String;
  const Instructions: String;
  const Prompt: String;
  var Response: String;
  EchoResponse: Boolean
) of Object;

property OnSSHKeyboardInteractive: TSSHKeyboardInteractiveEvent read FOnSSHKeyboardInteractive write FOnSSHKeyboardInteractive;

Remarks

SSHKeyboardInteractive is fired during the user authentication stage of the 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

type TSSHServerAuthenticationEvent = procedure (
  Sender: TObject;
  HostKey: String;
  HostKeyB: TBytes;
  const Fingerprint: String;
  const KeyAlgorithm: String;
  const CertSubject: String;
  const CertIssuer: String;
  const Status: String;
  var Accept: Boolean
) of Object;

property OnSSHServerAuthentication: TSSHServerAuthenticationEvent read FOnSSHServerAuthentication write FOnSSHServerAuthentication;

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
To limit the accepted host key algorithms refer to SSHPublicKeyAlgorithms.

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 Component)

Shows the progress of the secure connection.

Syntax

type TSSHStatusEvent = procedure (
  Sender: TObject;
  const Message: String
) of Object;

property OnSSHStatus: TSSHStatusEvent read FOnSSHStatus write FOnSSHStatus;

Remarks

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

Firewall Type

This is 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

AutoDetect
Boolean

This property tells the component whether or not to automatically detect and use firewall system settings, if available.

FirewallType
TiphFirewallTypes

This property determines the type of firewall to connect through. The applicable values are as follows:

fwNone (0)No firewall (default setting).
fwTunnel (1)Connect through a tunneling proxy. Port is set to 80.
fwSOCKS4 (2)Connect through a SOCKS4 Proxy. Port is set to 1080.
fwSOCKS5 (3)Connect through a SOCKS5 Proxy. Port is set to 1080.
fwSOCKS4A (10)Connect through a SOCKS4A Proxy. Port is set to 1080.

Host
String

This property contains the name or IP address of firewall (optional). If a Host is given, the requested connections will be authenticated through the specified firewall when connecting.

If this property is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, this property is set to the corresponding address. If the search is not successful, the component raises an exception.

Password
String

This property contains a password if authentication is to be used when connecting through the firewall. If Host is specified, the User and Password properties are used to connect and authenticate to the given firewall. If the authentication fails, the component raises an exception.

Port
Integer

This property contains the transmission control protocol (TCP) port for the firewall Host. See the description of the Host property for details.

Note: This property is set automatically when FirewallType is set to a valid value. See the description of the FirewallType property for details.

User
String

This property contains a user name if authentication is to be used connecting through a firewall. If the Host is specified, this property and Password properties are used to connect and authenticate to the given Firewall. If the authentication fails, the component raises an exception.

Constructors

constructor Create();

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

BytesSent
Integer

The number of bytes actually sent after a sending channel data.

ChannelId
String

An id generated by the component to identify the current SSH channel. This id is unique to this channel.

ConnectedAddress
String

This property holds the remote address to which the connection was established. This should match the Address parameter passed to the RequestForwarding method.

ConnectedPort
Integer

This property holds the remote port to which the connection was established. This should match the Port parameter passed to the RequestForwarding method.

DataToSend
String

A string of data to be sent to the remote host. Write-only property.

Assigning a string to the DataToSend makes the component send the string to the remote host.

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

DataToSendB
TBytes

A string of data to be sent to the remote host. Write-only property.

Assigning a string to the DataToSend makes the component send the string to the remote host.

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

ForwardingHost
String

Holds the host to which incoming traffic is forwarded. This is only applicable if local forwarding was requested when calling RequestForwarding.

ForwardingPort
Integer

Holds the port to which incoming traffic is forwarded. This is only applicable if local forwarding was requested when calling RequestForwarding.

OriginAddress
String

This property holds the address of the client which originated the connection to the reverse tunnel on SSHHost.

OriginPort
Integer

This property holds the port used by the client which originated the connection to the reverse tunnel on SSHHost.

Service
String

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

Configuration Settings (SSHReverseTunnel Component)

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

SSHReverseTunnel Configuration Settings

AutoReconnect:   Whether to automatically reestablish the SSH connection.

If the connection to SSHHost is broken the component will automatically reconnect to the server based on the value provided here. Possible values are:

0 Do not automatically reconnect
1 (default) Reconnect if an existing connection is broken
2 Retry initial connection from SSHLogon as well as reconnecting if an existing connection is broken

The default value is 1 meaning the component will automatically reconnect if an existing connection is broken.

See MaxRetryCount and RetryInterval for additional related settings.

When reconnecting after an SSH connection is established the component will attempt to reestablish any SSH tunnels that were previously established. The same retry values defined in MaxRetryCount and RetryInterval apply to reestablishing tunnels as well.

DefaultChannelIdleTimeout:   The inactivity timeout for channels.

This setting specifies the idle timeout in seconds for each connected channel. If there is no activity on the channel for the specified timeout the channel is closed and the client is disconnected.

The default value is 0 which is treated as an infinite timeout (the channel is never closed due to inactivity).

ForwardedPort:   The remote port which is forwarded.

When calling RequestForwarding with a value of 0 for the port parameter, the server will assign the port automatically. This setting may be queried to determine the port that was assigned by the server.

ForwardingLocalHost:   The interface on which to bind when forwarding data.

When the component is configured to automatically forward data to a destination this setting may be used to specify the interface to which the component binds when establishing the connection to the forwarding host.

This may be set to an IP address in the form aaa.bbb.ccc.ddd. By default this is unspecified and the system will automatically select the interface.

MaxRetryCount:   The maximum number of retries when reconnecting.

This setting defines the maximum number of connection attempts performed when reestablishing a broken connection. This is only applicable when AutoReconnect is set to 1 or 2. The default value is 0 (Infinite).

RetryInterval:   The interval in seconds between reconnect attempts.

This setting specifies the number of seconds between reconnection attempts. This is only applicable when AutoReconnect is set to 1 or 2. The default value is 5.

SSHClient Configuration Settings

ClientSSHVersionString:   The SSH version string used by the component.

This configuration setting specifies the SSH version string used by the component. The default value is "SSH-2.0-IPWorks SSH Client 2022".

EnablePageantAuth:   Whether to use a key stored in Pageant to perform client authentication.

This setting controls whether Pageant authentication is disabled, enabled, or required. When enabled or required, the component attempts to communicate with PuTTY's ssh-agent, called "Pageant", over shared memory to perform public key authentication. Possible values and the corresponding behavior is described below:

ValueDescription
0 (Disabled - default) No communication with Pageant is attempted.
1 (Enabled) Pageant authentication is used if available. If Pageant is not running, or does not contain the expected key no error is thrown.
2 (Required) Only Pageant authentication is used. If Pageant is not running, or does not contain the expected key an error is thrown.

Example enabling Pageant: component.Config("EnablePageantAuth=1"); component.SSHUser = "sshuser"; component.SSHLogon("localhost", 22);

Note: This functionality is only available on Windows.

KerberosDelegation:   If true, asks for credentials with delegation enabled during authentication.

The default value is "True". If set to "False", the client will not ask for credentials delegation support during authentication. Note that even if the client asks for delegation, the server/KDC might not grant it and authentication will still succeed.

KerberosRealm:   The fully qualified domain name of the Kerberos Realm to use for GSSAPI authentication.

This property may be set to the fully qualified (DNS) name of the kerberos realm (or Windows Active Directory domain name) to use during GSSAPI authentication. This can be used to force authentication with a given realm if the client and server machines are not part of the same domain.

KerberosSPN:   The Kerberos Service Principal Name of the SSH host.

This property can be set to specify the Service Principal Name (SPN) associated with the SSH service on the remote host. This will usually be in the form "host/fqdn.of.sshhost[@REALM]". If not specified, the component will assume the SPN is based on the value of the SSHHost property and the kerberos realm used for authentication.

KeyRenegotiationThreshold:   Sets the threshold for the SSH Key Renegotiation.

This property allows you to specify the threshold, in the number of bytes, for the SSH Key Renegotiation. The default value for this property is set to 1 GB.

Example (for setting the threshold to 500 MB): SSHComponent.Config("KeyRenegotiationThreshold=524288000")

LogLevel:   Specifies the level of detail that is logged.

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

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

MaxPacketSize:   The maximum packet size of the channel, in bytes.

This setting specifies the maximum size of an individual data packet, in bytes, that can be sent to the sender.

MaxWindowSize:   The maximum window size allowed for the channel, in bytes.

This setting specifies how many bytes of channel data can be sent to the sender of this message without adjusting the window. Note that this value may be changed during the connection, but the window size can only be increased, not decreased.

PasswordPrompt:   The text of the password prompt used in keyboard-interactive authentication.

This setting optionally specifies a pattern to be matched to the prompt received from the server during keyboard-interactive authentication. If a matching prompt is detected the component automatically responds to the prompt with the password specified by SSHPassword.

This provides an easy way to automatically reply to prompts with the password if one is presented by the server. The password will be auto-filled in the Response parameter of the SSHKeyboardInteractive event in the case of a match.

The following special characters are supported for pattern matching:

? Any single character.
* Any characters or no characters. I.E., C*t matches Cat, Cot, Coast, Ct, etc)
[,-] A range of characters. E.g.: [a-z], [a], [0-9], [0-9,a-d,f,r-z], etc.
\ The slash is ignored and exact matching is performed on the next character.

If the above characters need to be used as a literal in a pattern then they must be escaped by surrounding them with a []. (Note, "]" and "-" do not need to be escaped) See below for the escape sequences:

CharacterEscape Sequence
? [?]
* [*]
[ [[]
\ [\]

For example, to match the value [Something].txt specify the pattern [[]Something].txt

PreferredDHGroupBits:   The size (in bits) of the preferred modulus (p) to request from the server.

This may be when using the diffie-hellman-group-exchange-sha1 or diffie-hellman-group-exchange-sha256 key exchange algorithms to control the preferred size, in bits, of the modulus (p) prime number to request from the server. Acceptable values are between 1024 and 8192.

RecordLength:   The length of received data records.

If set to a positive value, this setting defines the length of data records to be received. The component will accumulate data until RecordLength is reached and only then fire the DataIn event with data of length RecordLength. This allows data to be received as records of known length. This value can be changed at any time, including within the DataIn event.

The default value is 0, meaning this setting is not used.

ServerSSHVersionString:   The remote host's SSH version string.

This will return the remote host's SSH version string, which can help when identifying problematic servers. This configuration setting is read-only.

SignedSSHCert:   The CA signed client public key used when authenticating.

When authenticating via public key authentication this setting may be set to the CA signed client's public key. This is useful when the server has been configured to trust client keys signed by a particular CA. For instance: component.Config("SignedSSHCert=ssh-rsa-cert-v01@openssh.com AAAAB3NzaC1yc2EAAAADAQABAAAB..."); The algorithm such as ssh-rsa-cert-v01@openssh.com in the above string is used as part of the authentication process. To use a different algorithm simply change this value. For instance all of the following are acceptable with the same signed public key:

  • ssh-rsa-cert-v01@openssh.com AAAAB3NzaC1yc2EAAAADAQABAAAB...
  • rsa-sha2-256-cert-v01@openssh.com AAAAB3NzaC1yc2EAAAADAQABAAAB...
  • rsa-sha2-512-cert-v01@openssh.com AAAAB3NzaC1yc2EAAAADAQABAAAB...

SSHAcceptAnyServerHostKey:   If set the component will accept any key presented by the server.

The default value is "False". Set this to "True" to accept any key presented by the server.

SSHAcceptServerCAKey:   The CA public key that signed the server's host key.

If the server's host key was signed by a CA, this setting may be used to specify the CA's public key. If specified the component will trust any server's host key that was signed by the CA. For instance: component.Config("SSHAcceptServerCAKey=ssh-rsa AAAAB3NzaC1yc2EAAAADAQAB...");

SSHAcceptServerHostKeyFingerPrint:   The fingerprint of the server key to accept.

This may be set to a comma-delimited collection of 16-byte MD5 fingerprints that should be accepted as the host's key. You may supply it by HEX encoding the values in the form "0a:1b:2c:3d". Example: SSHClient.Config("SSHAcceptServerHostKeyFingerprint=0a:1b:2c:3d"); If the server's fingerprint matches one of the values supplied, the component will accept the host key.

SSHFingerprintHashAlgorithm:   The algorithm used to calculate the fingerprint.

This configuration setting controls which hash algorithm is used to calculate the hostkey's fingerprint, displayed when SSHServerAuthentication fires. Valid values are:

  • MD5
  • SHA1
  • SHA256 (default)
SSHFingerprintMD5:   The server hostkey's MD5 fingerprint.

This setting may be queried in SSHServerAuthentication to get the server hostkey's MD5 fingerprint.

SSHFingerprintSHA1:   The server hostkey's SHA1 fingerprint.

This setting may be queried in SSHServerAuthentication to get the server hostkey's SHA1 fingerprint.

SSHFingerprintSHA256:   The server hostkey's SHA256 fingerprint.

This setting may be queried in SSHServerAuthentication to get the server hostkey's SHA256 fingerprint.

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

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

SSHKeepAliveInterval:   The interval between keep alive packets.

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

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

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

SSHKeyExchangeAlgorithms:   Specifies the supported key exchange algorithms.

This may be used to specify the list of supported Key Exchange algorithms used during SSH negotiation. The value should contain a comma separated list of algorithms. Supported algorithms are:

  • curve25519-sha256
  • curve25519-sha256@libssh.org
  • diffie-hellman-group1-sha1
  • diffie-hellman-group14-sha1
  • diffie-hellman-group14-sha256
  • diffie-hellman-group16-sha512
  • diffie-hellman-group18-sha512
  • diffie-hellman-group-exchange-sha256
  • diffie-hellman-group-exchange-sha1
  • ecdh-sha2-nistp256
  • ecdh-sha2-nistp384
  • ecdh-sha2-nistp521
The default value is: curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1,diffie-hellman-group14-sha256,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,ecdh-sha2-nistp256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,ecdh-sha2-nistp384,ecdh-sha2-nistp521.
SSHKeyRenegotiate:   Causes the component to renegotiate the SSH keys.

Once this setting is set the component will renegotiate the SSH keys with the remote host.

Example: SSHClient.Config("SSHKeyRenegotiate")

SSHMacAlgorithms:   Specifies the supported Mac algorithms.

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

  • hmac-sha1
  • hmac-md5
  • hmac-sha1-96
  • hmac-md5-96
  • hmac-sha2-256
  • hmac-sha2-256-96
  • hmac-sha2-512
  • hmac-sha2-512-96
  • hmac-ripemd160
  • hmac-ripemd160-96
  • hmac-sha2-256-etm@openssh.com
  • hmac-sha2-512-etm@openssh.com
The default value is hmac-sha2-256,hmac-sha2-512,hmac-sha1,hmac-md5,hmac-ripemd160,hmac-sha1-96,hmac-md5-96,hmac-sha2-256-96,hmac-sha2-512-96,hmac-ripemd160-96,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com.
SSHPubKeyAuthSigAlgorithms:   Specifies the signature algorithm when attempting public key authentication.

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

The setting should be a comma separated list of algorithms ordered by preference. At runtime the component will evaluate each algorithm in the order specified here. If the algorithm is applicable to the certificate specified in SSHCert it will be used. If the algorithm is not applicable the component will evaluate the next algorithm. Possible values are:

  • ssh-rsa (default)
  • ssh-dss (default)
  • rsa-sha2-256 (default)
  • rsa-sha2-512 (default)
  • ecdsa-sha2-nistp256 (default - windows only)
  • ecdsa-sha2-nistp384 (default - windows only)
  • ecdsa-sha2-nistp521 (default - windows only)
  • x509v3-sign-rsa
  • x509v3-sign-dss

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

The default value in Unix/macOS/Java is ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss.

Note that ECDSA algorithms are only supported in Windows.

SSHPublicKeyAlgorithms:   Specifies the supported public key algorithms.

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

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

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

*SSH-1.99-*,*SSH-2.0-*,*SSH-2.99-*
TryAllAvailableAuthMethods:   If set to true, the component will try all available authentication methods.

The default value is False. When set to True, the component will try to authenticate using all methods that it has credentials for and the server supports.

WaitForChannelClose:   Whether to wait for channels to be closed before disconnected.

This setting controls whether the component will wait for a server response to the SSH_MSG_CHANNEL_CLOSE when disconnecting. When the component disconnects it will first attempt to close all open channels by sending a SSH_MSG_CHANNEL_CLOSE for each channel. This setting controls whether the component will wait for a server response after sending the messages.

When True (default) the component will wait for a response to the channel close message until the responses have been received, the server closes the connection, or Timeout seconds is reached.

When False the component will still send the channel close messages but will not wait for a response and will proceed to close the connection.

WaitForServerDisconnect:   Whether to wait for the server to close the connection.

This setting controls whether to wait for the server to close the connection when SSHLogoff is called.

When set to True the component will initiate the disconnection sequence by sending SSH_MSG_DISCONNECT but will not close the connection, and instead will wait for the server to close the connection. Setting this to True may be beneficial in circumstances where many connections are being established, to avoid port exhaustion when sockets are in a TIME_WAIT state. Allowing the server to close the connection avoids the TIME_WAIT state of socket on the client machine.

When set to False (default) the client will close the connection. It is recommended to use this value unless there is a specific need to change it.

IPPort Configuration Settings

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

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

ConnectionTimeout:   Sets a separate timeout value for establishing a connection.

When set, this configuration setting allows you to specify a different timeout value for establishing a connection. Otherwise, the component will use Timeout for establishing a connection and transmitting/receiving data.

FirewallAutoDetect:   Tells the component whether or not to automatically detect and use firewall system settings, if available.

This setting is provided for use by components that do not directly expose Firewall properties.

FirewallHost:   Name or IP address of firewall (optional).

If a FirewallHost is given, requested connections will be authenticated through the specified firewall when connecting.

If the FirewallHost setting is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, the FirewallHost setting is set to the corresponding address. If the search is not successful, an error is returned.

NOTE: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallPassword:   Password to be used if authentication is to be used when connecting through the firewall.

If FirewallHost is specified, the FirewallUser and FirewallPassword settings are used to connect and authenticate to the given firewall. If the authentication fails, the component raises an exception.

NOTE: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallPort:   The TCP port for the FirewallHost;.

Note that the FirewallPort is set automatically when FirewallType is set to a valid value.

NOTE: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallType:   Determines the type of firewall to connect through.

The appropriate values are as follows:

0No firewall (default setting).
1Connect through a tunneling proxy. FirewallPort is set to 80.
2Connect through a SOCKS4 Proxy. FirewallPort is set to 1080.
3Connect through a SOCKS5 Proxy. FirewallPort is set to 1080.
10Connect through a SOCKS4A Proxy. FirewallPort is set to 1080.

NOTE: This setting is provided for use by components that do not directly expose Firewall properties.

FirewallUser:   A user name if authentication is to be used connecting through a firewall.

If the FirewallHost is specified, the FirewallUser and FirewallPassword settings are used to connect and authenticate to the Firewall. If the authentication fails, the component raises an exception.

NOTE: This setting is provided for use by components that do not directly expose Firewall properties.

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

When set, TCPKeepAlive will automatically be set to true. A TCP keep-alive packet will be sent after a period of inactivity as defined by KeepAliveTime. If no acknowledgement is received from the remote host the keep-alive packet will be re-sent. This setting specifies the interval at which the successive keep-alive packets are sent in milliseconds. This system default if this value is not specified here is 1 second.

Note: This value is not applicable in macOS.

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

When set, TCPKeepAlive will automatically be set to true. By default the operating system will determine the time a connection is idle before a TCP keep-alive packet is sent. This system default if this value is not specified here is 2 hours. In many cases a shorter interval is more useful. Set this value to the desired interval in milliseconds.

Linger:   When set to True, connections are terminated gracefully.

This property controls how a connection is closed. The default is True.

In the case that Linger is True (default), there are two scenarios for determining how long the connection will linger. The first, if LingerTime is 0 (default), the system will attempt to send pending data for a connection until the default IP protocol timeout expires.

In the second scenario, LingerTime is a positive value, the system will attempt to send pending data until the specified LingerTime is reached. If this attempt fails, then the system will reset the connection.

The default behavior (which is also the default mode for stream sockets) might result in a long delay in closing the connection. Although the component returns control immediately, the system could hold system resources until all pending data is sent (even after your application closes).

Setting this property to False forces an immediate disconnection. If you know that the other side has received all the data you sent (by a client acknowledgment, for example), setting this property to False might be the appropriate course of action.

LingerTime:   Time in seconds to have the connection linger.

LingerTime is the time, in seconds, to leave the socket connection linger. This value is 0 by default, which means it will use the default IP protocol timeout.

LocalHost:   The name of the local host through which connections are initiated or accepted.

The LocalHost setting 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 component initiate connections (or accept in the case of server components) only through that interface.

If the component is connected, the LocalHost setting 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).

LocalPort:   The port in the local host where the component binds.

This 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 to 0 (default) enables the system to choose a port at random. The chosen port will be shown by LocalPort after the connection is established.

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

This; setting is useful when trying to connect to services that require a trusted port in the client side. An example is the remote shell (rsh) service in UNIX systems.

MaxLineLength:   The maximum amount of data to accumulate when no EOL is found.

MaxLineLength is the size of an internal buffer, which holds received data while waiting for an EOL string.

If an EOL string is found in the input stream before MaxLineLength bytes are received, the DataIn event is fired with the EOL parameter set to True, and the buffer is reset.

If no EOL is found, and MaxLineLength bytes are accumulated in the buffer, the DataIn event is fired with the EOL parameter set to False, and the buffer is reset.

The minimum value for MaxLineLength is 256 bytes. The default value is 2048 bytes.

MaxTransferRate:   The transfer rate limit in bytes per second.

This setting can be used to throttle outbound TCP traffic. Set this to the number of bytes to be sent per second. By default this is not set and there is no limit.

ProxyExceptionsList:   A semicolon separated list of hosts and IPs to bypass when using a proxy.

This setting optionally specifies a semicolon separated list of hostnames or IP addresses to bypass when a proxy is in use. When requests are made to hosts specified in this property the proxy will not be used. For instance:

www.google.com;www.nsoftware.com

TCPKeepAlive:   Determines whether or not the keep alive socket option is enabled.

If set to true, the socket's keep-alive option is enabled and keep-alive packets will be sent periodically to maintain the connection. Set KeepAliveTime and KeepAliveInterval to configure the timing of the keep-alive packets.

Note: This value is not applicable in Java.

TcpNoDelay:   Whether or not to delay when sending packets.

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

By default, this config is set to false.

UseIPv6:   Whether to use IPv6.

When set to 0 (default), the component will use IPv4 exclusively. When set to 1, the component will use IPv6 exclusively. To instruct the component to prefer IPv6 addresses, but use IPv4 if IPv6 is not supported on the system, this setting should be set to 2. The default value is 0. Possible values are:

0 IPv4 Only
1 IPv6 Only
2 IPv6 with IPv4 fallback

Socket Configuration Settings

AbsoluteTimeout:   Determines whether timeouts are inactivity timeouts or absolute timeouts.

If AbsoluteTimeout is set to True, any method which does not complete within Timeout seconds will be aborted. By default, AbsoluteTimeout is False, and the timeout is an inactivity timeout.

Note: This option is not valid for UDP ports.

FirewallData:   Used to send extra data to the firewall.

When the firewall is a tunneling proxy, use this property to send custom (additional) headers to the firewall (e.g. headers for custom authentication schemes).

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

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

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

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

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

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

Base Configuration Settings

BuildInfo:   Information about the product's build.

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

CodePage:   The system code page used for Unicode to Multibyte translations.

The default code page is Unicode UTF-8 (65001).

The following is a list of valid code page identifiers:

IdentifierName
037IBM EBCDIC - U.S./Canada
437OEM - United States
500IBM EBCDIC - International
708Arabic - ASMO 708
709Arabic - ASMO 449+, BCON V4
710Arabic - Transparent Arabic
720Arabic - Transparent ASMO
737OEM - Greek (formerly 437G)
775OEM - Baltic
850OEM - Multilingual Latin I
852OEM - Latin II
855OEM - Cyrillic (primarily Russian)
857OEM - Turkish
858OEM - Multilingual Latin I + Euro symbol
860OEM - Portuguese
861OEM - Icelandic
862OEM - Hebrew
863OEM - Canadian-French
864OEM - Arabic
865OEM - Nordic
866OEM - Russian
869OEM - Modern Greek
870IBM EBCDIC - Multilingual/ROECE (Latin-2)
874ANSI/OEM - Thai (same as 28605, ISO 8859-15)
875IBM EBCDIC - Modern Greek
932ANSI/OEM - Japanese, Shift-JIS
936ANSI/OEM - Simplified Chinese (PRC, Singapore)
949ANSI/OEM - Korean (Unified Hangul Code)
950ANSI/OEM - Traditional Chinese (Taiwan; Hong Kong SAR, PRC)
1026IBM EBCDIC - Turkish (Latin-5)
1047IBM EBCDIC - Latin 1/Open System
1140IBM EBCDIC - U.S./Canada (037 + Euro symbol)
1141IBM EBCDIC - Germany (20273 + Euro symbol)
1142IBM EBCDIC - Denmark/Norway (20277 + Euro symbol)
1143IBM EBCDIC - Finland/Sweden (20278 + Euro symbol)
1144IBM EBCDIC - Italy (20280 + Euro symbol)
1145IBM EBCDIC - Latin America/Spain (20284 + Euro symbol)
1146IBM EBCDIC - United Kingdom (20285 + Euro symbol)
1147IBM EBCDIC - France (20297 + Euro symbol)
1148IBM EBCDIC - International (500 + Euro symbol)
1149IBM EBCDIC - Icelandic (20871 + Euro symbol)
1200Unicode UCS-2 Little-Endian (BMP of ISO 10646)
1201Unicode UCS-2 Big-Endian
1250ANSI - Central European
1251ANSI - Cyrillic
1252ANSI - Latin I
1253ANSI - Greek
1254ANSI - Turkish
1255ANSI - Hebrew
1256ANSI - Arabic
1257ANSI - Baltic
1258ANSI/OEM - Vietnamese
1361Korean (Johab)
10000MAC - Roman
10001MAC - Japanese
10002MAC - Traditional Chinese (Big5)
10003MAC - Korean
10004MAC - Arabic
10005MAC - Hebrew
10006MAC - Greek I
10007MAC - Cyrillic
10008MAC - Simplified Chinese (GB 2312)
10010MAC - Romania
10017MAC - Ukraine
10021MAC - Thai
10029MAC - Latin II
10079MAC - Icelandic
10081MAC - Turkish
10082MAC - Croatia
12000Unicode UCS-4 Little-Endian
12001Unicode UCS-4 Big-Endian
20000CNS - Taiwan
20001TCA - Taiwan
20002Eten - Taiwan
20003IBM5550 - Taiwan
20004TeleText - Taiwan
20005Wang - Taiwan
20105IA5 IRV International Alphabet No. 5 (7-bit)
20106IA5 German (7-bit)
20107IA5 Swedish (7-bit)
20108IA5 Norwegian (7-bit)
20127US-ASCII (7-bit)
20261T.61
20269ISO 6937 Non-Spacing Accent
20273IBM EBCDIC - Germany
20277IBM EBCDIC - Denmark/Norway
20278IBM EBCDIC - Finland/Sweden
20280IBM EBCDIC - Italy
20284IBM EBCDIC - Latin America/Spain
20285IBM EBCDIC - United Kingdom
20290IBM EBCDIC - Japanese Katakana Extended
20297IBM EBCDIC - France
20420IBM EBCDIC - Arabic
20423IBM EBCDIC - Greek
20424IBM EBCDIC - Hebrew
20833IBM EBCDIC - Korean Extended
20838IBM EBCDIC - Thai
20866Russian - KOI8-R
20871IBM EBCDIC - Icelandic
20880IBM EBCDIC - Cyrillic (Russian)
20905IBM EBCDIC - Turkish
20924IBM EBCDIC - Latin-1/Open System (1047 + Euro symbol)
20932JIS X 0208-1990 & 0121-1990
20936Simplified Chinese (GB2312)
21025IBM EBCDIC - Cyrillic (Serbian, Bulgarian)
21027Extended Alpha Lowercase
21866Ukrainian (KOI8-U)
28591ISO 8859-1 Latin I
28592ISO 8859-2 Central Europe
28593ISO 8859-3 Latin 3
28594ISO 8859-4 Baltic
28595ISO 8859-5 Cyrillic
28596ISO 8859-6 Arabic
28597ISO 8859-7 Greek
28598ISO 8859-8 Hebrew
28599ISO 8859-9 Latin 5
28605ISO 8859-15 Latin 9
29001Europa 3
38598ISO 8859-8 Hebrew
50220ISO 2022 Japanese with no halfwidth Katakana
50221ISO 2022 Japanese with halfwidth Katakana
50222ISO 2022 Japanese JIS X 0201-1989
50225ISO 2022 Korean
50227ISO 2022 Simplified Chinese
50229ISO 2022 Traditional Chinese
50930Japanese (Katakana) Extended
50931US/Canada and Japanese
50933Korean Extended and Korean
50935Simplified Chinese Extended and Simplified Chinese
50936Simplified Chinese
50937US/Canada and Traditional Chinese
50939Japanese (Latin) Extended and Japanese
51932EUC - Japanese
51936EUC - Simplified Chinese
51949EUC - Korean
51950EUC - Traditional Chinese
52936HZ-GB2312 Simplified Chinese
54936Windows XP: GB18030 Simplified Chinese (4 Byte)
57002ISCII Devanagari
57003ISCII Bengali
57004ISCII Tamil
57005ISCII Telugu
57006ISCII Assamese
57007ISCII Oriya
57008ISCII Kannada
57009ISCII Malayalam
57010ISCII Gujarati
57011ISCII Punjabi
65000Unicode UTF-7
65001Unicode UTF-8

The following is a list of valid code page identifiers for Mac OS only:

IdentifierName
1ASCII
2NEXTSTEP
3JapaneseEUC
4UTF8
5ISOLatin1
6Symbol
7NonLossyASCII
8ShiftJIS
9ISOLatin2
10Unicode
11WindowsCP1251
12WindowsCP1252
13WindowsCP1253
14WindowsCP1254
15WindowsCP1250
21ISO2022JP
30MacOSRoman
10UTF16String
0x90000100UTF16BigEndian
0x94000100UTF16LittleEndian
0x8c000100UTF32String
0x98000100UTF32BigEndian
0x9c000100UTF32LittleEndian
65536Proprietary

LicenseInfo:   Information about the current license.

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

  • Product: The product the license is for.
  • Product Key: The key the license was generated from.
  • License Source: Where the license was found (e.g., RuntimeLicense, License File).
  • License Type: The type of license installed (e.g., Royalty Free, Single Server).
UseInternalSecurityAPI:   Tells the component whether or not to use the system security libraries or an internal implementation.

By default the component will use the system security libraries to perform cryptographic functions. Setting this to True tells the component to use the internal implementation instead of using the system's security API.

Trappable Errors (SSHReverseTunnel Component)

SSHReverseTunnel Errors

10057   Reconnection limit exceeded for SSH tunnel.

SSHClient Errors

1001   Server has disconnected.
1002   Protocol version unsupported or other issue with version string.
1003   Cannot negotiate algorithms.
1005   Selected algorithm unsupported.
1006   Cannot set keys.
1010   Unexpected algorithm.
1011   Cannot create exchange hash.
1012   Cannot make key.
1013   Cannot sign data.
1014   Cannot encrypt packet.
1015   Cannot decrypt packet.
1016   Cannot decompress packet.
1020   Failure to open channel.
1021   Invalid channel ID.
1022   Invalid channel data.
1023   Invalid channel message.
1024   SSH message unimplemented.
1027   Server message unsupported.
1030   Server's host key was rejected. The host key may be accepted within the SSHServerAuthentication event or using the SSHAcceptServerHostKey property.
1031   Cannot verify server's host key.
1032   Authentication failed. Check description for details.
1033   Channel request failed.
1034   Diffie-Hellman exchange failed.
1036   SSH connection failed.
1037   SSH reconnect limit reached.
1038   Elliptic Curve Diffie-Hellman exchange failed.
1039   SSH keep-alive limit reached.
1098   Request failure.
1130   Would block error.
1133   Would block, reason: key reExchange.

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

IPPort Errors

100   You cannot change the RemotePort at this time. A connection is in progress.
101   You cannot change the RemoteHost (Server) at this time. A connection is in progress.
102   The RemoteHost address is invalid (0.0.0.0).
104   Already connected. If you want to reconnect, close the current connection first.
106   You cannot change the LocalPort at this time. A connection is in progress.
107   You cannot change the LocalHost at this time. A connection is in progress.
112   You cannot change MaxLineLength at this time. A connection is in progress.
116   RemotePort cannot be zero. Please specify a valid service port number.
117   Cannot change UseConnection option while the component is Active.
135   Operation would block.
201   Timeout.
211   Action impossible in control's present state.
212   Action impossible while not connected.
213   Action impossible while listening.
301   Timeout.
302   Could not open file.
434   Unable to convert string to selected CodePage
1105   Already connecting. If you want to reconnect, close the current connection first.
1117   You need to connect first.
1119   You cannot change the LocalHost at this time. A connection is in progress.
1120   Connection dropped by remote host.

TCP/IP Errors

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

Copyright (c) 2022 /n software inc. - All rights reserved.
IPWorks SSH 2022 Delphi Edition - Version 22.0 [Build 8172]