node-tcp-proxy

node-tcp-proxy

A simple TCP proxy that may be used to access a service on another network. An extensible replacement for socat when used thus

socat TCP-LISTEN:port,fork TCP:host:port

port is where socat listens for incoming requests. host:port are the host and port where the actual service is listening at.

To achieve the same with node-tcp-proxy

tcpproxy  --proxyPort port [--hostname <name or IP>] --serviceHost host1,host2 --servicePort port1,port2 [--q] [--tls [both]] [--pfx file] [--passphrase secret]

Optionally, hostname specifies the IP address to listen at. Node.js listens on unspecified IPv6 address :: by default. If serviceHost and servicePort specify a comma separated list, the proxy will perform load balancing on a round-robin basis.

TLS can be enabled at the proxy port using the tls option. If followed by both, TLS is also used with the service. Use pfx option to specify server certificate, and passphrase to provide the password required to access it.

npm

Install node-tcp-proxy from npm, thus

sudo npm install -g node-tcp-proxy

Programming Interface

To create a proxy in your own code

var proxy = require("node-tcp-proxy");
var newProxy = proxy.createProxy(8080, "host", 10080);

To end the proxy

newProxy.end();

hostname can be provided through an optional fourth parameter e.g. {hostname: 0.0.0.0} to createProxy. Console output may be silenced by adding quiet: true e.g. {hostname: 0.0.0.0, quiet: true}.

If you specify more than one service host and port pair, the proxy will perform round-robin load balancing

var hosts = ["host1", "host2"];
var ports = [10080, 10080];
var newProxy = proxy.createProxy(8080, hosts, ports);
// or var newProxy = proxy.createProxy(8080, "host1,host2", "10080,10080");

You can intercept and modify data sent in either direction, and modify the service host selection strategy

var proxy = require("node-tcp-proxy");
var util = require("util");
var serviceHosts = ["www.google.com", "www.bing.com"];
var servicePorts = [80, 80];
var newProxy = proxy.createProxy(8080, serviceHosts, servicePorts, {
    upstream: function(context, data) {
        console.log(util.format("Client %s:%s sent:",
            context.proxySocket.remoteAddress,
            context.proxySocket.remotePort));
        // do something with the data and return modified data
        return data;
    },
    downstream: function(context, data) {
        console.log(util.format("Service %s:%s sent:",
            context.serviceSocket.remoteAddress,
            context.serviceSocket.remotePort));
        // do something with the data and return modified data
        return data;
    },
    serviceHostSelected: function(proxySocket, i) {
        console.log(util.format("Service host %s:%s selected for client %s:%s.",
            serviceHosts[i],
            servicePorts[i],
            proxySocket.remoteAddress,
            proxySocket.remotePort));
        // use your own strategy to calculate i
        return i;
    }
});

Alternatives

You may want to check out these interesting alternatives

• http-proxy - programmable proxying library that supports websockets. It is suitable for implementing components such as reverse proxies and load balancers.

• sslh - accepts connections on specified ports, and forwards them further based on tests performed on the first data packet sent by the remote client.

• socat - socat is a relay for bidirectional data transfer between two independent data channels. Each of these data channels may be a file, pipe, device (serial line etc. or a pseudo terminal), a socket (UNIX, IP4, IP6 - raw, UDP, TCP), an SSL socket, proxy CONNECT connection, a file descriptor (stdin etc.), the GNU line editor (readline), a program, or a combination of two of these.