README.md
# node-tcp-proxy [](https://www.codacy.com/gh/tewarid/node-tcp-proxy/dashboard?utm_source=github.com&utm_medium=referral&utm_content=tewarid/node-tcp-proxy&utm_campaign=Badge_Grade) [](https://codeclimate.com/github/tewarid/node-tcp-proxy/maintainability)
A [classical](https://tools.ietf.org/html/rfc1919) 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 <name or IP>] --serviceHost host1,host2 --servicePort port1,port2 [--q] [--tls [both]] [--pfx file] [--passphrase secret]
```
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.
## npm
Install node-tcp-proxy using [npm](https://www.npmjs.com/package/node-tcp-proxy)
```bash
sudo npm install -g node-tcp-proxy
```
## Programming Interface
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;
}
});
```
## Alternatives
You may want to check out these interesting alternatives
* [http-proxy](https://github.com/http-party/node-http-proxy) - programmable proxying library that supports websockets. It is suitable for implementing components such as reverse proxies and load balancers.
* [sslh](https://github.com/yrutschle/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](http://www.dest-unreach.org/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.