Maybe you’re concerned about anonymity or you just want know and experiment how actually things work. You can find a lot of documentation about such topics on the Internet.
This is my take on a little portion of the argument, inspired by some questions recently appeared on netfilter and redsocks mailing lists.
So, you want to telnet a server from your workstation and need to establish an anonymous connection via a third machine (let’s name it proxy), I mean that the server cannot trace back your IP address (neither workstation nor proxy): I’ll show you the Tor method.
I guess you already know what Tor is, otherwise maybe this article is not for you.
Let’s assume you have full control of the proxy machine and can install a Gnu/Linux distribution on it, Ubuntu server 13.10 for instance.
Install Tor and tor-arm (a terminal status monitor):
apt-get install tor tor-arm
Verify Tor is running and listening:
netstat -antup|grep tor
tcp 0 0 127.0.0.1:9050 0.0.0.0:* LISTEN 1806/tor
On that port Tor is waiting for a TCP session able to carry the final destination of the transiting packets. That means you need another piece of software to do the job: socat, a multipurpose relay.
Install socat:
apt-get install socat
Socat can listen for a connection and forward it to a host via a socks4 server (Tor in our example).
Now, let’s put down some names and addresses:
- client: 192.0.2.1/24
- proxy server: 198.51.100.128/24
- telnet server: 203.0.113.254/24
192.0.2.1 wants to telnet 203.0.113.254 via 198.51.100.128, right.
This is a possible schema:
192.0.2.1:[random port] (client)
|
|
198.51.100.128:2300 (proxy server: socat)
|
127.0.0.1:9050 (TOR)
|
|
|—-TOR CLOUD—-|
|
|
203.0.113.254:23 (telnet server)
Run socat:
socat TCP4-LISTEN:2300,reuseaddr,fork SOCKS4:127.0.0.1:203.0.113.254:23,socksport=9050
Everything is ready: go for an anonymous telnet session from the client:
telnet 198.51.100.128 2300
Trying 198.51.100.128...
Connected to 198.51.100.128
Escape character is '^]'.
The session is flowing through the Tor network thanks to a socks proxy in the middle. To view a bandwidth graph of your connection, use arm.
If you want to select Tor exit nodes, you could put something like this in your torrc:
StrictExitNodes 1
ExitNodes {IT}, {UK}, {FR}, {DE}, {CH}, {ES}, {AT}, {PT}, {GR}, {RU}, {NL}, {LU}, {BE}, {UA}, {DK}, {LT}, {LV}, {VA}, {FI}, {SE}, {NO}, {IS}, {CS}, {CZ}, {PL}, {EE}, {HU}, {IR}, {LI}, {MC}, {ME}, {MF}, {SI}
Pretty simple, huh?
Disclaimer.
This is just a quick and practical how to: you are warmly encouraged to read the documentation of each piece of software involved to know what exactly you are doing.
How to make a TCP connection flow through Tor on Ubuntu 13.10 with socat by Antonio Prado is licensed under a Creative Commons Attribution-ShareAlike 4.0 International