Zig 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.

Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

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

    const tunnel = try chilkat.Socket.init();
    defer tunnel.deinit();

    const ssh_hostname = "sftp.example.com";
    const ssh_port = 22;

    // Connect to an SSH server and establish the SSH tunnel:
    tunnel.sshOpenTunnel(ssh_hostname, ssh_port) catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        return;
    };

    // Authenticate with the SSH server via a login/password
    // or with a public key.
    // This example demonstrates SSH password authentication.
    tunnel.sshAuthenticatePw("mySshLogin", "mySshPassword") catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        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
    const max_wait_ms = 4000;
    const use_tls = false;
    const channel = try chilkat.Socket.init();
    defer channel.deinit();
    tunnel.sshNewChannel("time-c.nist.gov", 37, use_tls, max_wait_ms, channel) catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        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.
    const big_endian = true;
    channel.receiveInt32(big_endian) catch {
        std.debug.print("{s}\n", .{try channel.getLastErrorText(alloc)});
        return;
    };

    const dt = try chilkat.DateTime.init();
    defer dt.deinit();
    dt.setFromNtpTime(channel.getReceivedInt()) catch {};

    // Show the current local date/time
    const b_local_time = true;
    std.debug.print("Current local date/time: {s}\n", .{try dt.getAsRfc822(alloc, b_local_time)});

    // Close the SSH channel.
    channel.close(max_wait_ms) catch {
        std.debug.print("{s}\n", .{try channel.getLastErrorText(alloc)});
        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.
    tunnel.sshNewChannel("time-a.nist.gov", 37, use_tls, max_wait_ms, channel) catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        return;
    };

    // Review the LastErrorText to see that the connection was made via the SSH tunnel:
    std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});

    // 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.
    channel.close(max_wait_ms) catch {
        std.debug.print("{s}\n", .{try channel.getLastErrorText(alloc)});
        return;
    };

    // Finally, close the SSH tunnel.
    tunnel.sshCloseTunnel() catch {
        std.debug.print("{s}\n", .{try tunnel.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("TCP SSH tunneling example completed.\n", .{});
}