Bugtraq mailing list archives
Re: Small TCP packets == very large overhead == DoS?
From: "Crist Clark" <crist.clark () globalstar com>
Date: Wed, 18 Jul 2001 14:31:47 -0700
Pavel Machek wrote:
Hi!If any of you have tested what happens to the ability of a box to perform well when it has a small MTU you will know that setting the MTY to (say) 56 on a diskless thing is a VERY VERY bad idea when NFS read/write packets are generally 8k in size. Do not try it on a NFS thing unless you plan to reboot it, ok ? Last time I did this was when I worked out you could fragment packets inside the TCP header and that lesson was enough for me ;_)AFAI can remember, there's minimum MTU defined for IP (something like 576)... ...and then there are networks like hamradio that use lower MTU. They are really non-compliant, but Linux wants them to work.
No, there is no minimum MTU. However, all IP-compliant hosts must be able to handle 576-byte datagrams. That is, the network to which a host is attached may have a smaller MTU, but the host must be able to handle reassembled datagrams that are 576-bytes long. The 576-byte requirement is what the host's network stack must handle (that set of algorithms in software or hardware) and does not have anything to do with requirements on the network medium. -- Crist J. Clark Network Security Engineer crist.clark () globalstar com Globalstar, L.P. (408) 933-4387 FAX: (408) 933-4926 The information contained in this e-mail message is confidential, intended only for the use of the individual or entity named above. If the reader of this e-mail is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any review, dissemination, distribution or copying of this communication is strictly prohibited. If you have received this e-mail in error, please contact postmaster () globalstar com
Current thread:
- Small TCP packets == very large overhead == DoS? Darren Reed (Jul 07)
- Re: Small TCP packets == very large overhead == DoS? Darren Reed (Jul 09)
- RE: Small TCP packets == very large overhead == DoS? David LeBlanc (Jul 09)
- Re: Small TCP packets == very large overhead == DoS? Pavel Machek (Jul 15)
- Re: Small TCP packets == very large overhead == DoS? Crist Clark (Jul 19)
- <Possible follow-ups>
- Re: Small TCP packets == very large overhead == DoS? Eric Vyncke (Jul 09)
- RE: Small TCP packets == very large overhead == DoS? Russ (Jul 09)
- Re: Small TCP packets == very large overhead == DoS? Darren Reed (Jul 10)
- RE: Small TCP packets == very large overhead == DoS? David LeBlanc (Jul 10)
- Re: Small TCP packets == very large overhead == DoS? Darren Reed (Jul 10)
- Re: Small TCP packets == very large overhead == DoS? gregory duchemin (Jul 09)
- Re: Small TCP packets == very large overhead == DoS? Darren Reed (Jul 09)
- Re: Small TCP packets == very large overhead == DoS? John Kristoff (Jul 10)
- Re: Small TCP packets == very large overhead == DoS? Brett Lymn (Jul 10)
- RE: Small TCP packets == very large overhead == DoS? Franck Martin (Jul 10)
- Re: Small TCP packets == very large overhead == DoS? Crist Clark (Jul 18)