Open a direct-tcpip Channel (SSH Port Forwarding)

See more SSH Examples

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.

Chilkat C# Downloads

Download Chilkat for C#

bool 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.

Chilkat.Ssh ssh = new Chilkat.Ssh();

int sshPort = 22;
success = ssh.Connect("ssh.example.com",sshPort);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

//  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.
string password = "mySshPassword";

success = ssh.AuthenticatePw("mySshLogin",password);
if (success == false) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

//  The target name is resolved by the SSH server, not by this computer, so it must be
//  reachable from the server's network.
string targetHostname = "db.internal.example.com";
int targetPort = 5432;
int channelNum = ssh.OpenDirectTcpIpChannel(targetHostname,targetPort);
if (channelNum < 0) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

Debug.WriteLine("Opened direct-tcpip channel: " + Convert.ToString(channelNum));

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

ssh.Disconnect();