tcprelay

tcprelay

tcprelay helps client accessing the host unreachable. For example:

• Virtual machine vm1 runing on server A, with NAT ip 192.168.122.*.
• Server A has public IP 192.168.1.10.
• Client can access server A, but can not access tcp port 80 of vm1 directly.
• With tcprelay running on server A.
• Client can access tcp port 80 of vm1 directly by 192.168.1.10:8080.

Figure

Client A can not direct access target machine, for some reason firewall or NAT etc.
The other middle machine can access target. Tcp client can access target with tcp by tcprelay running on middle machine.

                                             +----------------+
                                             |                |
        +------------------------------->    |     target     |(vm1)
        |     can not direct access          |                |
        |                                    +----------------+
        |                                             ^  192.168.122.*:80
        |                                             |
        |                                             | 
        |                                             |  192.168.122.1
+--------------+                             +----------------+
|              | 192.168.1.20                |                |
|   client A   | +------------------------>  |     server A   |(tcprelay)
|              |           192.168.1.10:8080 |                |
+--------------+                             +----------------+

how to run

on server A, run tcprelay.

./tcprelay -l ":8080"  -t "192.168.122.101:80"

It will listen on 8080, and all the client connected to :8080 will be relay to 192.168.1.101:80

For the client, just type http://1.2.3.4:8080 you can access the web service on target machine.

how to build

download this code, cd into the dir. type command as follows:

SET GOOS=linux
SET GOARCH=amd64
SET GOPROXY=https://goproxy.cn
go build .

download

if you don't want to compile it. just download in release page.
It's very easy to use.

reference

This program is taken from this two repository. they are the hero.

https://github.com/xtaci/kcptun
https://github.com/hikaricai/p2p_tun

powerful another port mapping tool

gost is a powerful relay tool.
https://github.com/ginuerzh/gost
It's easy to use, like this.

./gost -L  tcp://:8080/192.168.122.101:80