Rust

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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// 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.

let ssh = chilkat::Ssh::new();

let ssh_port = 22;
if ssh.connect("ssh.example.com", ssh_port).is_err() {
    println!("{}", ssh.last_error_text());
    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.
let password = "mySshPassword".to_string();

if ssh.authenticate_pw("mySshLogin", &password).is_err() {
    println!("{}", ssh.last_error_text());
    return;
}

// The target name is resolved by the SSH server, not by this computer, so it must be
// reachable from the server's network.
let target_hostname = "db.internal.example.com".to_string();
let target_port = 5432;
let channel_num = ssh.open_direct_tcp_ip_channel(&target_hostname, target_port);
if channel_num < 0 {
    println!("{}", ssh.last_error_text());
    return;
}

println!("Opened direct-tcpip channel: {}", channel_num);

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

ssh.disconnect();