PureBasic

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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PureBasic

IncludeFile "CkSsh.pb"

Procedure ChilkatExample()

    success.i = 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.

    ssh.i = CkSsh::ckCreate()
    If ssh.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  Set the SOCKS proxy properties before connecting.  The hostname may be a domain name or an
    ;  IP address.
    CkSsh::setCkSocksHostname(ssh, "socks.example.com")
    CkSsh::setCkSocksPort(ssh, 1080)
    CkSsh::setCkSocksUsername(ssh, "mySocksLogin")
    CkSsh::setCkSocksPassword(ssh, "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.
    CkSsh::setCkSocksVersion(ssh, 5)

    hostname.s = "ssh.example.com"
    port.i = 22
    success = CkSsh::ckConnect(ssh,hostname,port)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    Debug "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.
    password.s = "mySshPassword"

    success = CkSsh::ckAuthenticatePw(ssh,"mySshLogin",password)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    ;  ... use the SSH connection normally ...

    CkSsh::ckDisconnect(ssh)


    CkSsh::ckDispose(ssh)


    ProcedureReturn
EndProcedure