Visual FoxPro

SSH Through a SOCKS Proxy

Demonstrates connecting to an SSH server through a SOCKS4 or SOCKS5 proxy. Set the SOCKS properties before calling Connect, and set SocksVersion to match the proxy server.

Background: SOCKS is a general-purpose TCP relay, so unlike an HTTP proxy it is designed from the start to carry arbitrary protocols — usually the smoother option for SSH. The version matters: SOCKS4 supports only a username with no password, while SOCKS5 supports full login/password authentication as well as IPv6 and remote DNS resolution. Note this is the inverse of dynamic port forwarding: here a SOCKS proxy is used to reach the SSH server, rather than SSH providing a SOCKS proxy.

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LOCAL lnSuccess
LOCAL loSsh
LOCAL lcHostname
LOCAL lnPort
LOCAL lcPassword

lnSuccess = 0

*  This example requires the Chilkat API to have been previously unlocked.
*  See Global Unlock Sample for sample code.

*  Demonstrates connecting to an SSH server through a SOCKS4 or SOCKS5 proxy.

loSsh = CreateObject('Chilkat.Ssh')

*  Set the SOCKS proxy properties before connecting.  The hostname may be a domain name or an
*  IP address.
loSsh.SocksHostname = "socks.example.com"
loSsh.SocksPort = 1080
loSsh.SocksUsername = "mySocksLogin"
loSsh.SocksPassword = "mySocksPassword"

*  Set the version to match the proxy server: 4 or 5.
*  Note: SOCKS4 supports only a username, with no password.  SOCKS5 supports full
*  login/password authentication.
loSsh.SocksVersion = 5

lcHostname = "ssh.example.com"
lnPort = 22
lnSuccess = loSsh.Connect(lcHostname,lnPort)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

? "Connected to the SSH server through the SOCKS proxy."

*  Normally you would not hard-code the password in source.  You should instead obtain it
*  from an interactive prompt, environment variable, or a secrets vault.
lcPassword = "mySshPassword"

lnSuccess = loSsh.AuthenticatePw("mySshLogin",lcPassword)
IF (lnSuccess = 0) THEN
    ? loSsh.LastErrorText
    RELEASE loSsh
    CANCEL
ENDIF

*  ... use the SSH connection normally ...

loSsh.Disconnect()

RELEASE loSsh