forward.js

An efficient port forwarding utility

Why I made it

• On Windows, nc/ncat/socat.exe can not be trusted because they are not signed.
• I want a prototype so can be easily modified to do more works such as dump, analyse data.
• I want to see connection info CLEARLY which almost not provided by nc/ncat/socat.
• The nc/ncat/socat's port forwarding are low efficiency or can not serve multiple connections.
• I don't want to remember complicated arguments for socat, and also nc which are distribution-dependent.

Usage

(You can also install it by npm install -g forward.js)

Listen at a local port and forward incoming connections to other host:port.

forward.js [localAddress:]port [destHost:]port

Note:

• IPv6 address must be wrapped by square brackets, e.g.[::1]:8080

Samples

Forward TCP port 8080 of all interfaces, to a.b.c:9090

forward.js 8080 a.b.c:9090

Forward TCP port 8080 of all IPv4 interfaces to an IPv6 address's 9090 port

forward.js 0.0.0.0:8080 [2001:db8:a0b:12f0::1]:9090

Forward TCP port 8080 of all IPv6 interfaces to 192.168.1.12:9090

forward.js [::]:8080 192.168.1.12:9090

Screenshot:

$ forward.js 9999 www.google.com:80
Using parameters {
  "localAddress": "",
  "localPort": 9999,
  "destHost": "www.google.com",
  "destPort": 80
}
Listening at [::]:9999
Incoming connection will be forwarded to [www.google.com]:80

Press ENTER to toggle Log level.
  0: No (default)
  1: Show connection
  2: Dump all req/res data


Log level 1: Show connection


Log level 2: Dump all req/res data

====[::ffff:127.0.0.1]:56618 Connected from [::ffff:127.0.0.1]:56618
====[::ffff:127.0.0.1]:56618 Connect to [www.google.com]:80
====[::ffff:127.0.0.1]:56618 Connected to [216.58.197.4]:80 src [192.168.11.3]:64287

====[::ffff:127.0.0.1]:56618 <REQ>Data:>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
GET / HTTP/1.1


====[::ffff:127.0.0.1]:56618 <RES>Data:<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
HTTP/1.1 404 Found
...


====[::ffff:127.0.0.1]:56618 <RES>Data:<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
...

====[::ffff:127.0.0.1]:56618 <REQ>Ended
====[::ffff:127.0.0.1]:56618 <RES>Ended

Do not worry about the log of listening at ::(all IPv6 interfaces), as far as i'v tested, on Windows and Mac OS X, listening at :: will cause all IPv4 interfaces being listened either.(called dual-stack).

Test client: (nc-connect.js is here)

$ nc-connect.js 9999
Connected to 127.0.0.1:9999 source 127.0.0.1:56618
GET / HTTP/1.1

HTTP/1.1 302 Found
...