On Mon, 21 Feb 2000 out of nowhere LigerTeam spoke:
~ :The flag value Each one correspond to 1 bit,
~ :but it have unused 2 bit.
~ :
~ :|unused|unused|URG|ACK|PSH|RST|SYN|FIN|
~ :
~ :Understanding of the very problem is simple.
not new. These bits have been already used by queso fingerprints while ago
(`f' type of packet). Whether these bits are considered or ignored also
apparently depends on the tcp-stack implementation. (linux vs. MacOS f.e)
~ :When the flags variable in tcp header is adjusted
~ :totally with given value,
~ :higher two bit(unused bit) must be cleared
~ :and set at 0.
wouldn't agree. By rfc two higher bits here are considered `reserved' and
should be set to `0'. Having seen these bits being set to `1' is already a
good indication of hostile activity or broken hardware in your network, so
you should be able to spot these packets too.
--
Key fingerprint = 4422 16FC 3C7D E10A B044 CA4F 2BE0 3943 9758 9324
http://www.kalug.lug.net/fygrave/
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 15:36:45 PDT