Tcl

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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Tcl


load ./chilkat.dll

set success 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.

set ssh [new_CkSsh]

#  Set the SOCKS proxy properties before connecting.  The hostname may be a domain name or an
#  IP address.
CkSsh_put_SocksHostname $ssh "socks.example.com"
CkSsh_put_SocksPort $ssh 1080
CkSsh_put_SocksUsername $ssh "mySocksLogin"
CkSsh_put_SocksPassword $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_put_SocksVersion $ssh 5

set hostname "ssh.example.com"
set port 22
set success [CkSsh_Connect $ssh $hostname $port]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

puts "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.
set password "mySshPassword"

set success [CkSsh_AuthenticatePw $ssh "mySshLogin" $password]
if {$success == 0} then {
    puts [CkSsh_lastErrorText $ssh]
    delete_CkSsh $ssh
    exit
}

#  ... use the SSH connection normally ...

CkSsh_Disconnect $ssh

delete_CkSsh $ssh