Tcpigeon

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It carries messages over long distances and it will generally return to its nest.

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Tcpigeon is a simple transparent TCP proxy implementation you can use for debugging purposes. It acts as a mitm entity which intercepts, logs and delivers TCP messages from client(s) to server in both directions.

Use cases

• You wrote a communication protocol and you need to verify the data exchanged between source and destination.
• You have to inspect the payload of every TCP message sent by two end-points.

This is the scenario:

                              <===> client 1
remote server <===> TCPIGEON  <===> client 2
                              ...
                              <===> client n

Install

npm:

$ npm install tcpigeon [-g]

or clone the repository:

git clone https://github.com/skanna/tcpigeon.git

Require

var Tcpigeon = require('tcpigeon'); 

See examples.

Tests

If you don't have mocha installed you need to install devDependecies:

$ cd tcpigeon
$ npm install

Run tests:

$ npm test

Options

options = {
    proxy_port  : 30080,          // proxy port
    proxy_addr  : '127.0.0.1',    // proxy address
    remote_port : null,           // remote server port - mandatory
    remote_host : null,           // remote server host - mandatory
    encoding    : 'utf8',         // character encoding
    logging     : 'file',         // log type
    max_conn    : 100             // max allowed connections
}

• remote_port and remote_host are mandatory, the other parameters have default values as shown.
• encoding can assume the same values as in the Buffer module.
• logging possible values are: "file" (default), "console" or "nolog".
• The max_conn value should be equal to the remote server capacity, at least.

Methods

// Run proxy
Tcpigeon#fly(Object tcpigeon_options) : net.Server
 
// Stop proxy
Tcpigeon#land() : undefined
 
// Drop the connection to the specified client
Tcpigeon#kill(ip_address) : undefined
 
// Returns the list of the open sockets in the form 'ip_address:port'
Tcpigeon#flock() : Array

The fly method returns null in case of configuration error, (ie an option in a bad format). In case there are many open sockets shared with the same client the kill method will destroy the first one it finds.

Events

Custom events:

// new connection - a pigeon can fly
// source format is ip_address:port
'carrier' : function(String source)
 
// a pigeon has a new message for you
'post'    : function(String message) 
 
// a pigeon was killed :(
'killed'  : function(Number clients)
 
// error - no more flying pigeons 
'falling' : function(Object Error)

Logging

Each line is preceded by a datetime value and a symbol that categorizes it. Use these symbols to spot:

• (EE) errors
• (WW) warnings
• (II) general informations
• (++) new connections
• (--) disconnections
• (<<) client to server direction
• (>>) server to client direction

The length of every message is printed too.

example:

9/28/2017, 3:48:43 PM - (II) Tcpigeon Server listening to {"address":"127.0.0.1","family":"IPv4","port":30080}
9/28/2017, 3:48:51 PM - (++) connection from 127.0.0.1:51313
9/28/2017, 3:48:51 PM - (II) 1 clients currently connected
9/28/2017, 3:48:51 PM - (<<) from 127.0.0.1:51313: client ONE - length: 10 bytes
9/28/2017, 3:48:51 PM - (<<) client ONE - length: 10 bytes
9/28/2017, 3:48:51 PM - (>>) client ONE - length: 10 bytes
9/28/2017, 3:48:51 PM - (>>) to 127.0.0.1:51313: client ONE - length: 10 bytes

Acknowledgements

Coding style is inpired to the modules written by @rootslab 👍 (have a look!!)

Thank you for giving me a lot of precious suggestions!