Lua Requires Chilkat v11.0.0+

TCP Socket through SSH Tunnel (Port Forwarding)

See more Socket/SSL/TLS Examples

Demonstrates using Chilkat Socket to communicate to a TCP service through an SSH tunnel. This example will connect to an NIST time server and (using the old Time Protocol (RFC 868)), will read the current GMT time.

Note: This is not necessarily a recommended means for getting the current date/time. The most commonly used time protocol is the Network Time Protocol (RFC-1305). The intent of this example is to show how TCP communications can occur through an SSH tunnel.

Lua

local chilkat = require("chilkat")

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

local tunnel = chilkat.Socket.new()

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

-- Connect to an SSH server and establish the SSH tunnel:
local success = tunnel:ssh_open_tunnel(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:ssh_authenticate_pw("mySshLogin", "mySshPassword")
if not success then
    print(tunnel.last_error_text)
    return
end

-- OK, the SSH tunnel is setup.  Now open a channel within the tunnel.
-- Once the channel is obtained, the Socket API may
-- be used exactly the same as usual, except all communications
-- are sent through the channel in the SSH tunnel.
-- Any number of channels may be created from the same SSH tunnel.
-- Multiple channels may coexist at the same time.

-- Connect to an NIST time server and read the current date/time
local maxWaitMs = 4000
local useTls = false
local channel = chilkat.Socket.new()
success = tunnel:ssh_new_channel("time-c.nist.gov", 37, useTls, maxWaitMs, channel)
if not success then
    print(tunnel.last_error_text)
    return
end

-- The time server will send a big-endian 32-bit integer representing
-- the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
-- The ReceiveInt32 method will receive a 4-byte integer, but returns
-- true or false to indicate success.  If successful, the integer
-- is obtained via the ReceivedInt property.
local bigEndian = true
success = channel:receive_int32(bigEndian)
if not success then
    print(channel.last_error_text)
    return
end

local dt = chilkat.DateTime.new()
dt:set_from_ntp_time(channel.received_int)

-- Show the current local date/time
local bLocalTime = true
print("Current local date/time: " .. dt:get_as_rfc822(bLocalTime))

-- Close the SSH channel.
success = channel:close(maxWaitMs)
if not success then
    print(channel.last_error_text)
    return
end

-- It is possible to create a new channel from the existing SSH tunnel for the next connection:
-- Any number of channels may be created from the same SSH tunnel.
-- Multiple channels may coexist at the same time.
success = tunnel:ssh_new_channel("time-a.nist.gov", 37, useTls, maxWaitMs, channel)
if not success then
    print(tunnel.last_error_text)
    return
end

-- Review the LastErrorText to see that the connection was made via the SSH tunnel:
print(tunnel.last_error_text)

-- Close the connection to time-a.nist.gov.  This is actually closing our channel
-- within the SSH tunnel, but keeps the tunnel open for the next port-forwarded connection.
success = channel:close(maxWaitMs)
if not success then
    print(channel.last_error_text)
    return
end

-- Finally, close the SSH tunnel.
success = tunnel:ssh_close_tunnel()
if not success then
    print(tunnel.last_error_text)
    return
end

print("TCP SSH tunneling example completed.")