Lua

FTP through SSH Tunnel with Dynamic Port Forwarding

See more FTP Examples

Demonstrates how to start a background thread that runs a portable SSH tunnel w/ dynamic port forwarding that the foreground thread can be used for establishing FTP sessions through an SSH tunnel.

Note: Some developers may be accustomed to starting an stunnel.exe proxy from https://www.stunnel.org. The stunnel.exe is not necessary here. Chilkat's background thread fulfills the task of what the external stunnel.exe does. Therefore, your application is self-contained, meaning that it can run anywhere because the SSH tunnel proxy is built-in.

Lua

local chilkat = require("chilkat")

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

local success = false

local tunnel = chilkat.SshTunnel.new()

local sshHostname = "sftp.example.com"
local sshPort = 22

-- Connect to an SSH server and establish the SSH tunnel:
success = tunnel:connect(sshHostname, sshPort)
if not success then
    print(tunnel.last_error_text)
    return
end

-- Authenticate with the SSH server via a login/password
-- or with a public key.
-- This example demonstrates SSH password authentication.
success = tunnel:authenticate_pw("mySshLogin", "mySshPassword")
if not success then
    print(tunnel.last_error_text)
    return
end

-- Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
-- with dynamic port forwarding:
tunnel.dynamic_port_forwarding = true

-- We may optionally require that connecting clients authenticate with our SOCKS proxy server.
-- To do this, set an inbound username/password.  Any connecting clients would be required to
-- use SOCKS5 with the correct username/password.
-- If no inbound username/password is set, then our SOCKS proxy server will accept both
-- SOCKS4 and SOCKS5 unauthenticated connections.

tunnel.inbound_socks_username = "chilkat123"
tunnel.inbound_socks_password = "password123"

-- Start the listen/accept thread to begin accepting SOCKS proxy client connections.
-- Listen on port 1080.
success = tunnel:begin_accepting(1080)
if not success then
    print(tunnel.last_error_text)
    return
end

-- Now that a background thread is running a SOCKS proxy server that forwards connections
-- through an SSH tunnel, it is possible to use any Chilkat implemented protocol that is SOCKS capable,
-- such as HTTP, POP3, SMTP, IMAP, FTP, etc.  The protocol may use SSL/TLS because the SSL/TLS
-- will be passed through the SSH tunnel to the end-destination.  Also, any number of simultaneous
-- connections may be routed through the SSH tunnel.

local ftp = chilkat.Ftp2.new()

-- Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
ftp.socks_hostname = "localhost"
-- The SocksPort must equal the port passed to BeginAccepting above.
ftp.socks_port = 1080
ftp.socks_version = 5
-- The SOCKS5 login/password set here must equal the InboundSocksUsername/Password set above.
ftp.socks_username = "chilkat123"
ftp.socks_password = "password123"

-- This is the actual FTP server domain or IP address, and the login/password for the user account on the destination FTP server.
ftp.hostname = "ftp.someFtpServer.com"
ftp.username = "myLogin"
ftp.password = "myPassword"
ftp.auth_tls = true

-- Connect and login (via the SSH tunnel) to the FTP server.
success = ftp:connect()
if not success then
    print(ftp.last_error_text)
    return
end

-- Change to the remote directory where the file is located.
-- This step is only necessary if the file is not in the root directory
-- for the FTP account.
success = ftp:change_remote_dir("junk")
if not success then
    print(ftp.last_error_text)
    return
end

local localFilename = "c:/temp/hamlet.xml"
local remoteFilename = "hamlet.xml"

-- Download a file.  (the data connection is also automatically established through the
-- SSH tunnel using dynamic port forwarding..)
success = ftp:get_file(remoteFilename, localFilename)
if not success then
    print(ftp.last_error_text)
    return
end

-- The disconnect is disconnecting with the FTP server and closes the SSH tunnel.
-- The background tunnel thread is still running, and may be used for subsequent FTP connections,
-- or even connections for any other purpose, such as HTTP, IMAP, SMTP, POP3, etc.
success = ftp:disconnect()

-- When the app is finished with the tunnel, it can cleanup..

-- Stop the background listen/accept thread:
local waitForThreadExit = true
success = tunnel:stop_accepting(waitForThreadExit)
if not success then
    print(tunnel.last_error_text)
    return
end

-- Close the SSH tunnel (would also kick any remaining connected clients).
success = tunnel:close_tunnel(waitForThreadExit)
if not success then
    print(tunnel.last_error_text)
    return
end