ICMP filtering, was Re: ICANN Targets DDoS Attacks

Wed Oct 30 06:14:49 UTC 2002

## On 2002-10-29 19:55 -0600 Rob Thomas typed:

RT> 
RT> Hi, NANOGers.
RT> 
RT> ] 	ICMP?
RT> 
RT> I have my own thoughts on ICMP filtering, which you will find here:
RT> 
RT> http://www.cymru.com/Documents/icmp-messages.html
RT> 
RT> I don't claim to have correct thoughts, however, so input and suggestions
RT> are always welcome.  :)  If anyone could pick up a NANOG t-shirt for me,
RT> that would be welcome as well.  :)

Hi Rob

 I find it hard to believe You have no thoughts about:

  1) rate-limiting ICMP 

  2) passing ICMP "statefully"
 (that is for example ICMP echo reply only accepted in reply to an ICMP echo)

  3) DoS problems related to ICMP unreachables

-- 
Regards,
	Rafi

RT> 
RT> Thanks,
RT> Rob.
RT> 