Home page logo
/

fulldisclosure logo Full Disclosure mailing list archives

Re: ICMP (was: daily internet traffic report)
From: Cedric Blancher <blancher () cartel-securite fr>
Date: Sun, 17 Oct 2004 23:46:11 +0200

Le dim 17/10/2004 à 22:21, James Edwards a écrit :
So, blocking ***all*** ICMP ***types*** is bad but you can block some
***types*** without getting into trouble. Till you understand that all
the types do in relation to networking I would leave the alone.

Nowadays, using a decent stateful firewall allows one to get rid of ICMP
filtering by associating ICMP errors to existing connections. As an
example, when filtering using Netfilter, ICMP errors triggered by known
IP connections are recognized as such (i.e. RELATED state) and thus can
be filtered in a different way unsollicited ones (i.e. INVALID state)
are.

This kind of feature allows one not to block valid ICMP stuff and keep
away from direct ICMP solicitations you can filter the way you want.

My 0.02€...


-- 
http://www.netexit.com/~sid/
PGP KeyID: 157E98EE FingerPrint: FA62226DA9E72FA8AECAA240008B480E157E98EE
Hi! I'm your friendly neighbourhood signature virus.
Copy me to your signature file and help me spread!

_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.netsys.com/full-disclosure-charter.html


  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]
AlienVault