Swift

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.

Swift

func chilkatTest() {
    var success: Bool = false

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

    let tunnel = CkoSocket()!

    var sshHostname: String? = "sftp.example.com"
    var sshPort: Int = 22

    // Connect to an SSH server and establish the SSH tunnel:
    success = tunnel.sshOpenTunnel(sshHostname: sshHostname, sshPort: sshPort)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    // Authenticate with the SSH server via a login/password
    // or with a public key.
    // This example demonstrates SSH password authentication.
    success = tunnel.sshAuthenticatePw(sshLogin: "mySshLogin", sshPassword: "mySshPassword")
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    // 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
    var maxWaitMs: Int = 4000
    var useTls: Bool = false
    let channel = CkoSocket()!
    success = tunnel.sshNewChannel(hostname: "time-c.nist.gov", port: 37, ssl: useTls, maxWaitMs: maxWaitMs, channel: channel)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    // 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.
    var bigEndian: Bool = true
    success = channel.receiveInt32(bigEndian: bigEndian)
    if success == false {
        print("\(channel.lastErrorText!)")
        return
    }

    let dt = CkoDateTime()!
    dt.set(fromNtpTime: channel.receivedInt.intValue)

    // Show the current local date/time
    var bLocalTime: Bool = true
    print("Current local date/time: \(dt.get(asRfc822: bLocalTime)!)")

    // Close the SSH channel.
    success = channel.close(maxWaitMs: maxWaitMs)
    if success != true {
        print("\(channel.lastErrorText!)")
        return
    }

    // 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.sshNewChannel(hostname: "time-a.nist.gov", port: 37, ssl: useTls, maxWaitMs: maxWaitMs, channel: channel)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    // Review the LastErrorText to see that the connection was made via the SSH tunnel:
    print("\(tunnel.lastErrorText!)")

    // 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: maxWaitMs)
    if success != true {
        print("\(channel.lastErrorText!)")
        return
    }

    // Finally, close the SSH tunnel.
    success = tunnel.sshCloseTunnel()
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    print("TCP SSH tunneling example completed.")

}