Xbase++

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 nSuccess
LOCAL oSsh
LOCAL cHostname
LOCAL nPort
LOCAL cPassword

nSuccess := 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.

oSsh := CreateObject("Chilkat.Ssh")

//  Set the SOCKS proxy properties before connecting.  The hostname may be a domain name or an
//  IP address.
oSsh:SocksHostname := "socks.example.com"
oSsh:SocksPort := 1080
oSsh:SocksUsername := "mySocksLogin"
oSsh: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.
oSsh:SocksVersion := 5

cHostname := "ssh.example.com"
nPort := 22
nSuccess := oSsh:Connect(cHostname, nPort)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
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.
cPassword := "mySshPassword"

nSuccess := oSsh:AuthenticatePw("mySshLogin", cPassword)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  ... use the SSH connection normally ...

oSsh:Disconnect()

oSsh:destroy()