Valentin Mihov's Blog

Random pieces of wisdom about technology

Hacking the package TTL with DD-WRT

Some ISPs are changing the TTL of the packets going to their customers to protect from splitting the network accounts to several people. This could be quite annoying when a person wants to use a wireless router, so she could use her laptop/ipod/whatever-you-like from every point in the house. Of course there is a solution. Here is mine:

  1. Get a Linksys WRT54GL wireless router (it runs linux!!!)

  2. Install DD-WRT firmware on it

  3. Go to the web interface of the router (usually http://192.168.1.1). Go to Administration->Commands and enter the following in the Commands textbox:

     iptables -t mangle -I PREROUTING -i vlan1 -j TTL --ttl-set 128
    
  4. Hit “Save Firewall” and you are ready to go!

This will set the TTL of all incoming packets to 128 ;-)