A simple TCP proxy built using Node.js
npm install node-tcp-proxyA classical TCP proxy that may be used to access a service on another network. An extensible replacement for socat when used thus
``bash`
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
`bash`
tcpproxy --proxyPort port [--hostname
Optionally, use --hostname to specify host or 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 --tls. Use --pfx followed by path to specify server certificate, and --passphrase to provide the password required to access it. Use --tls both, to also enable TLS with the service.
Install node-tcp-proxy using npm
`bash`
sudo npm install -g node-tcp-proxy
To create a proxy in your own code
`javascript`
var proxy = require("node-tcp-proxy");
var newProxy = proxy.createProxy(8080, "host", 10080);
To end the proxy
`javascript`
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
`javascript`
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
`javascript``
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;
}
});
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.