North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: Pattern matching odd HTTP request

  • From: Karsten W. Rohrbach
  • Date: Tue Sep 18 19:54:35 2001

Bill McGonigle([email protected])@2001.09.18 18:58:42 +0000:
> On Tuesday, September 18, 2001, at 06:30 PM, Jake Khuon wrote:
> >
> > You start to suspect a DDOS port-flood attack.  It's certainly causing 
> > me to
> > spawn a lot of httpds and occupying a lot of ports.
> On Apache 1.3, this brings the number of httpd processes up to 
> MaxClients, then each one waits 300 seconds (the default timeout) for 
> the connections to time out, at which point the other connections are 
> made, and the cycle continues.  A DDOS of this nature would be 
> particularly nasty.  One client (happened to be on localhost) tied up 
> the server for 6 minutes this way with the default Apache config.

indeed, that's nasty.
the quick fix action would be setting
    Timeout 5
in the httpd.conf, but this won't really fix the problem and make the
objects inaccessible for users with high latency links.

source ip based connection rate limiting would perhaps solve the
problem. are there any modules available out there to accomplish this

> Here's what the logfile for these attempts looks like:
> - - [18/Sep/2001:18:43:06 -0400] "-" 408 -
> Doh!

yup, i see them from time to time in some of my servers' logs, but not
at that rate jake reported. i cc'ed brian from the apache project,
perhaps they got some solution for this...


> CS Students do it in the pool.
KR433/KR11-RIPE -- WebMonster Community Founder -- nGENn GmbH Senior Techie -- --
karsten& -- alpha& -- alpha& -- [email protected]
GnuPG 0x2964BF46 2001-03-15 42F9 9FFF 50D4 2F38 DBEE  DF22 3340 4F4E 2964 BF46
Please do not remove my address from To: and Cc: fields in mailing lists. 10x

Attachment: pgp00017.pgp
Description: PGP signature