#!/zitstif.no-ip.org/

Ever want to access the internet without authenticating at your local college? Have you found yourself accessing wifi points at airports that require you to pay ‘X’ amount of dollars for service? Well my cheap friend, I have a solution for you!

I will for warn you, that this method is a bit slow and it does require *nix on both ends. Also this is for educational purposes only!

Firstly, you need an accessible server that is running ssh on it, along with a nifty program called ‘dns2tcp’. There are some other similar programs like iodine and such that can do this for you, but this walk-through is focused on the usage of dns2tcp. Also, you need a DNS name, which you can freely get via no-ip.com or dyndns.

File:

http://www.hsc.fr/ressources/outils/dns2tcp/index.html.en

Guide:

http://www.wains.be/index.php/2009/04/24/howto-setting-up-dns2tcp/

I followed this guide quite closely, and it actually did not end up working for me. The guide suggests to start the daemon via:

sudo /etc/init.d/dns2tcpd start

However, this did not work for me. By using netstat, I found that dns2tcpd was not even listening. Instead, I ended up using ‘/usr/local/bin/dns2tcpd’. But before I continue, I’ll post my dns2tcpd config file:

listen = 0.0.0.0
port = 53
# If you change this value, also change the USER variable in /etc/default/dns2tcpd
user = nobody
chroot = /tmp
domain = yourdomain.org
ressources = ssh:127.0.0.1:22

Change accordingly, and yes, ‘ressources’ is suppose to be misspelled.

Here is the command that has worked for me and I’m currently using to make this post possible:

sudo nohup dns2tcpd -f /etc/dns2tcpd.conf &

Verify that you’ve forwarded a port on your router to port 53 on your server, or if your server is in the DMZ, you shouldn’t have to worry about doing this.

Now, in a remote location that has restricted access (via redirecting every HTTP request to a login page), test that you’re server is visible via DNS by using a command like ‘host’. We’ll use my DNS name for this example:

host zitstif.no-ip.org
zitstif.no-ip.org has address 75.41.5.12

If this works, there’s a good chance you’re in business. Then, the next test you want to do is:

dns2tcpc -z zitstif.no-ip.org 75.41.5.12
Available connection(s) :
        ssh

If you see results like this, then chances are, this will work. Next, we need to do some DNS tunneling:

dns2tcpc zitstif.no-ip.org 75.41.5.12 -l 4444 -r ssh

If dns2tcpc is listening on port 4444, you now should be able to ssh into it and this will redirect you to your home server.

ssh -D 1234 user@localhost -p 4444

Once you’ve authenticated then you’re set to now setup firefox or a browser that supports SOCKS 4/5, to connect to your loopback interface on port 1234.

One big reason why I made mention of this, is because Hak5 had an episode showing how to do basically the same thing but they stated you had to pay for your own DNS service / name. My method works, and it’s also cheaper.