Lua

SSH Tunnel Through an Outbound SOCKS Proxy

Demonstrates reaching the SSH server through an outbound SOCKS proxy using the SocksVersion, SocksHostname, SocksPort, SocksUsername, and SocksPassword properties.

Background: This is the reverse direction from dynamic forwarding: here a SOCKS proxy is used to reach the SSH server, for networks where outbound connections must pass through one. SocksVersion is the switch — 0 means no SOCKS, while 4 or 5 selects the protocol. SOCKS5 supports username/password authentication and remote DNS; SOCKS4 supports only a username.

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Lua

local chilkat = require("chilkat")

-- Demonstrates reaching the SSH server through an outbound SOCKS proxy using the SshTunnel
-- properties SocksVersion, SocksHostname, SocksPort, SocksUsername, and SocksPassword.

local tunnel = chilkat.SshTunnel.new()

-- Set SocksVersion to 4 or 5 to route the outbound connection to the SSH server through a SOCKS
-- proxy.  A value of 0 (the default) means no SOCKS proxy.
tunnel.socks_version = 5
tunnel.socks_hostname = "socks.example.com"
tunnel.socks_port = 1080

-- SOCKS4 supports only a username; SOCKS5 supports username and password.
tunnel.socks_username = "myProxyLogin"
tunnel.socks_password = "myProxyPassword"

tunnel.dest_hostname = "db.internal.example.com"
tunnel.dest_port = 5432

-- Connect to the SSH server through the SOCKS proxy configured above.
local sshPort = 22
local success = tunnel:connect("ssh.example.com", sshPort)
if not success then
    print(tunnel.last_error_text)
    return
end

-- 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.
local password = "mySshPassword"

success = tunnel:authenticate_pw("mySshLogin", password)
if not success then
    print(tunnel.last_error_text)
    return
end

local listenPort = 1080
success = tunnel:begin_accepting(listenPort)
if not success then
    print(tunnel.last_error_text)
    return
end

print("Tunnel established through the SOCKS proxy.")

local waitForThreadExit = true
success = tunnel:close_tunnel(waitForThreadExit)
if not success then
    print(tunnel.last_error_text)
    return
end