Chilkat2-Python

Open a direct-tcpip Channel (SSH Port Forwarding)

Demonstrates the Chilkat Ssh.OpenDirectTcpIpChannel method, which opens a direct-tcpip channel through the SSH server to a target host and port. The first argument is the target hostname and the second is the target port. It returns the channel number, or -1 on failure.

Background: This is SSH local port forwarding at the API level: the channel carries ordinary TCP traffic to a service that may be reachable only from the SSH server's network — a database, an internal web app, a message broker. The key detail is that the server resolves the target name, not your machine, so it must resolve and be reachable there. Supplying a numeric IPv4 address avoids remote DNS resolution entirely.

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Chilkat2-Python

import sys
import chilkat2

success = False

# Demonstrates the Ssh.OpenDirectTcpIpChannel method, which opens a direct-tcpip channel
# through the SSH server to a target host and port.  The 1st argument is the target hostname
# and the 2nd is the target port.  It returns the channel number, or -1 on failure.

ssh = chilkat2.Ssh()

sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
if (success == False):
    print(ssh.LastErrorText)
    sys.exit()

# 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 = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
if (success == False):
    print(ssh.LastErrorText)
    sys.exit()

# The target name is resolved by the SSH server, not by this computer, so it must be
# reachable from the server's network.
targetHostname = "db.internal.example.com"
targetPort = 5432
channelNum = ssh.OpenDirectTcpIpChannel(targetHostname,targetPort)
if (channelNum < 0):
    print(ssh.LastErrorText)
    sys.exit()

print("Opened direct-tcpip channel: " + str(channelNum))

# The channel now carries ordinary TCP data to the target, tunneled over SSH.

ssh.Disconnect()