nanog mailing list archives
RE: Digital Island sponsors DoS attempt?
From: "Quibell, Marc" <mquibell () icn state ia us>
Date: Fri, 26 Oct 2001 13:47:14 -0500
I actually thought about that being a problem, only if you block ALL ICMP messages. Any router beyond the blocking one will break PMTU discovery, so yeah you're right. One could always deny specific ICMP types.... Marc -----Original Message----- From: Bob K [mailto:melange () yip org] Sent: Friday, October 26, 2001 1:45 PM To: Quibell, Marc Cc: nanog () merit edu Subject: RE: Digital Island sponsors DoS attempt? On Fri, 26 Oct 2001, Quibell, Marc wrote:
Finally, I do not believe PMTU uses pings to discover the PMTU. I believe
it
uses TCP or UDP packets at the layers above IP, and it DOES use "ICMP
Packet
Too big" responses (from the receiver) to cut it's packet size. So in reality, a router blocking ICMP from being routed through can still send these ICMP messages PMTU needs. Is this how you understand it?
Don't forget that routers or hosts beyond (from the point of view of the host attempting PMTU) your ICMP-blocking router may have smaller MTUs than the norm and may be trying to send ICMP errors back... -- Bob <melange () yip org> | We're all wrong.
Current thread:
- Re: Fwd: Re: Digital Island sponsors DoS attempt?, (continued)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Leo Bicknell (Oct 25)
- Re: Digital Island sponsors DoS attempt? Bandy Rush (Oct 25)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Jason Forester (Oct 25)
- RE: Fwd: Re: Digital Island sponsors DoS attempt? Borchers, Mark (Oct 26)
- RE: Digital Island sponsors DoS attempt? Quibell, Marc (Oct 26)
- Re: Digital Island sponsors DoS attempt? Valdis . Kletnieks (Oct 26)
- RE: Digital Island sponsors DoS attempt? Quibell, Marc (Oct 26)
- RE: Digital Island sponsors DoS attempt? Bob K (Oct 26)
- Re: Digital Island sponsors DoS attempt? Valdis . Kletnieks (Oct 26)
- RE: Digital Island sponsors DoS attempt? Nicholas Bastin (Oct 26)
- RE: Digital Island sponsors DoS attempt? Quibell, Marc (Oct 26)
- RE: Digital Island sponsors DoS attempt? Quibell, Marc (Oct 26)
- Re: Digital Island sponsors DoS attempt? Valdis . Kletnieks (Oct 26)
- Fwd: Re: Digital Island sponsors DoS attempt? Rodney Thayer (Oct 26)
- RE: Digital Island sponsors DoS attempt? Quibell, Marc (Oct 26)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Paul A Vixie (Oct 27)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Brian Whalen (Oct 27)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Leo Bicknell (Oct 27)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Paul Vixie (Oct 28)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Leo Bicknell (Oct 28)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Paul Vixie (Oct 28)
- Re: Fwd: Re: Digital Island sponsors DoS attempt? Brian Whalen (Oct 27)