Wednesday, July 9, 2008

MaraDNS is immune to the new cache poisoning attack.

MaraDNS is immune to the new cache poisoning attack. MaraDNS has always been immune to this attack. Ditto with Deadwood (indeed, people can use MaraDNS or Deadwood on the loopback interface to protect their machines from this attack).

OK, basically, this is an old problem DJB wrote about well over seven years ago. The solution is to randomize both the query ID and the source port; MaraDNS/Deadwood do this (and have been doing this since around the time of their first public releases that could resolve DNS queries) using a cryptographically strong random number generator (MaraDNS uses an AES variant; Deadwood uses the 32-bit version of Radio Gatun).

The only issue is Windows users not using Cygwin; please make sure random_seed_file points to a text file with secret that is at least 16 bytes long.