Infosec Instite n00bs CTF Labs LEVEL 4

URL :http://ctf.infosecinstitute.com/levelfour.php

Hint  :  HTTP means Hypertext Transfer Protocol

Try checking HTTP headers and cookies .
you ca use firefox pluging like HTTP headers or RETClient :

Status Code: 200 OK
Connection: Keep-Alive
Content-Encoding: gzip
Content-Length: 1235
Content-Type: text/html
Date: Sat, 14 Mar 2015 17:16:00 GMT
Keep-Alive: timeout=5, max=100
Server: Apache/2.4.7 (Ubuntu)
Set-Cookie: fusrodah=vasbfrp_syntvf_jrybirpbbxvrf
Vary: Accept-Encoding
X-Powered-By: PHP/5.5.9-1ubuntu4.6

check cookie  :

fusrodah=vasbfrp_syntvf_jrybirpbbxvrf

 try to check if its a substitution cipher 

http://en.wikipedia.org/wiki/Caesar_cipher  using cesar brutforce :

http://www.root-me.org/spip.php?page=outils&inc=code_decode

 ROT13 : http://en.wikipedia.org/wiki/ROT13

Flag :infosec_flagis_welovecookies