Swift

SSH Tunnel Through an Outbound SOCKS Proxy

Demonstrates reaching the SSH server through an outbound SOCKS proxy using the SocksVersion, SocksHostname, SocksPort, SocksUsername, and SocksPassword properties.

Background: This is the reverse direction from dynamic forwarding: here a SOCKS proxy is used to reach the SSH server, for networks where outbound connections must pass through one. SocksVersion is the switch — 0 means no SOCKS, while 4 or 5 selects the protocol. SOCKS5 supports username/password authentication and remote DNS; SOCKS4 supports only a username.

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Swift


func chilkatTest() {
    var success: Bool = false

    //  Demonstrates reaching the SSH server through an outbound SOCKS proxy using the SshTunnel
    //  properties SocksVersion, SocksHostname, SocksPort, SocksUsername, and SocksPassword.

    let tunnel = CkoSshTunnel()!

    //  Set SocksVersion to 4 or 5 to route the outbound connection to the SSH server through a SOCKS
    //  proxy.  A value of 0 (the default) means no SOCKS proxy.
    tunnel.socksVersion = 5
    tunnel.socksHostname = "socks.example.com"
    tunnel.socksPort = 1080

    //  SOCKS4 supports only a username; SOCKS5 supports username and password.
    tunnel.socksUsername = "myProxyLogin"
    tunnel.socksPassword = "myProxyPassword"

    tunnel.destHostname = "db.internal.example.com"
    tunnel.destPort = 5432

    //  Connect to the SSH server through the SOCKS proxy configured above.
    var sshPort: Int = 22
    success = tunnel.connect(hostname: "ssh.example.com", port: sshPort)
    if success == false {
        print("\(tunnel.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.
    var password: String? = "mySshPassword"

    success = tunnel.authenticatePw(login: "mySshLogin", password: password)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    var listenPort: Int = 1080
    success = tunnel.beginAccepting(listenPort: listenPort)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }

    print("Tunnel established through the SOCKS proxy.")

    var waitForThreadExit: Bool = true
    success = tunnel.closeTunnel(waitForThreads: waitForThreadExit)
    if success == false {
        print("\(tunnel.lastErrorText!)")
        return
    }


}