React Native

TCP or TLS over Multiple Hop SSH to Remote Server

See more Socket/SSL/TLS Examples

Demonstrates how to use the Chilkat Socket API to connect to a remote server (using TCP or TLS) tunneled through mulitple-hop SSH. The scheme looks like this:

Application => ServerSSH1 => ServerSSH2 => DestinationServer

The ConnectThroughSsh and UseSsh methods are added in Chilkat version 9.5.0.55 to accomplish this task.

React Native

import { Socket, Ssh } from '@chilkat/react-native'

async function chilkatExample() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  const ssh1 = new Ssh();

  // Connect directly to the 1st SSH server.
  try {
    await ssh1.connectAsync('serverssh1.com', 22);
  } catch {
    console.log(ssh1.lastErrorText);
    return;
  }

  // Authenticate using login/password:
  try {
    await ssh1.authenticatePwAsync('ssh1Login', 'ssh1Password');
  } catch {
    console.log(ssh1.lastErrorText);
    return;
  }

  // Connect through the 1st SSH connection to reach a 2nd SSH server.
  // Note: Any number of SSH connections may be simultaneously tunneled through a single
  // existing SSH connection.
  const ssh2 = new Ssh();
  try {
    await ssh2.connectThroughSshAsync(ssh1, 'serverssh2.com', 22);
  } catch {
    console.log(ssh2.lastErrorText);
    return;
  }

  // Authenticate with ssh2...
  try {
    await ssh2.authenticatePwAsync('ssh2Login', 'ssh2Password');
  } catch {
    console.log(ssh2.lastErrorText);
    return;
  }

  const socket = new Socket();

  // Tell the socket object to connect to our destination server though the ssh2 tunnel (which itself is routed through ssh1).
  // The connection looks like this:  ApplicationSocket(TLS) => ServerSSH1 => ServerSSH2 => DestinationServer
  try {
    socket.useSsh(ssh2);
  } catch {
    console.log(socket.lastErrorText);
    return;
  }

  // Connect using TLS to www.chilkatsoft.com
  // We could also tunnel a bare TCP connection by specifying port 80 with useTls = false.
  const useTls = true;
  const maxWaitMillisec = 20000;
  try {
    await socket.connectAsync('www.chilkatsoft.com', 443, useTls, maxWaitMillisec);
  } catch {
    console.log(socket.lastErrorText);
    return;
  }

  // Once the multiple hop SSH tunneled connection is setup,  the socket programming
  // is identical to the normal case where we have a direct connection.

  // Tell the socket object that all text is to be sent in the utf-8 encoding,
  // and the text received is assumed to be utf-8.
  socket.stringCharset = 'utf-8';

  // Send an HTTP HEAD request:
  try {
    await socket.sendStringAsync('HEAD / HTTP/1.1\r\nHost: www.chilkatsoft.com\r\n\r\n');
  } catch {
    console.log(socket.lastErrorText);
    return;
  }

  // Wait a maximum of 4 seconds while no data is forthcoming:
  socket.maxReadIdleMs = 4000;

  // Get the 1st response line, which should be "HTTP/1.1 200 OK"
  let responseStatusLine: string;
  try {
    responseStatusLine = await socket.receiveToCRLFAsync();
  } catch {
    console.log(socket.lastErrorText);
    return;
  }

  console.log(`StatusLine: ${responseStatusLine}`);

  // Now get the 1st line of the response header:
  let responseHeaderLine: string;
  try {
    responseHeaderLine = await socket.receiveToCRLFAsync();
  } catch {
    console.log(socket.lastErrorText);
    return;
  }

  console.log(`HeaderLine: ${responseHeaderLine}`);

  // Now read the remainder of the response header by reading until a double CRLF is seen:
  let remainderOfHeader: string;
  try {
    remainderOfHeader = await socket.receiveUntilMatchAsync('\r\n\r\n');
  } catch {
    console.log(socket.lastErrorText);
    return;
  }

  console.log(`Remainder: ${remainderOfHeader}`);

  // Close the connection with the server.  This closes the tunnel through ssh2.
  // Wait a max of 20 seconds (20000 millsec)
  await socket.closeAsync(20000);

  // Close the connection with ssh2.  (This closes the the tunnel through ssh1.)
  // The connection with ssh1 is still alive, and may be used for more connections.
  ssh2.disconnect();

  ssh1.disconnect();
}