Recently I needed to find out information about a Juniper router password which is stored as a hash in the router configuration. The tricky part is while the password hash is technically a MD5 hash it is modified to make it unique and make it harder to crack. Luckily there is a way to crack the hash using JTR (John The Ripper) though it will require that you also have the username associated to the password as the username is used as part of the salt for the hash. Below there is first information on how to crack Juniper hashes which are the same as Netscreen hashes followed by more information about the hash itself.
I am getting ready for a password contest at Defcon that Alex and I and a few other guys from the Hashcat team are going to enter and I decided to install John the Ripper on a Cent OS box in case I needed it for anything. John is in the yum repos however the version is pretty old and it is not compiled with NTLM support so I decided to build it from source so that i could apply the Jumbo patch which adds support for a whole lot of different algorithms which are normally only available in the pro version of John the Ripper.
Below I show the steps I took to get it compiled and working on Cent OS 64 bit: