Snort mailing list archives
Re: spoof detection?
From: Chris Green <cmg () uab edu>
Date: Tue, 13 Nov 2001 19:29:38 -0600
"Sheahan, Paul (PCLN-NW)" <Paul.Sheahan () priceline com> writes:
I was just reading an article on "How to Spot Source Address Spoofing". Pretty interesting. I was wondering if anyone is using Snort to try and detect when someone spoofs their address in an attempt to denial of service their site. It would go something like this: * Say my web server IP address is 200.200.200.200 * An attacker somewhere on the Net spoofs their source address to that of my web server (200.200.200.200), then starts sending out packets all over the Net on a certain port, say port 21 for example. * All machines on the Net receiving these packets that don't have port 21 open, respond to my web server with a RST, thinking my web server is the source of the packets. * So now my web server is receiving tons of RSTs from different hosts on the Net, where enough of them could cause a denial of service. Is there a way to setup Snort to look for a high threshold of RSTs so I can tell when someone might be spoofing my address and trying to cause a denial of service on my site?
No but the place to do that would probably be stream4. AFAICT, its a pretty poor DOS attack because you're only getting RST's generated that you should ignore and the cost of injecting syns to random hosts is costs the same as the resulting RST flood. It would have been much more effecient to SYN flood your irc server in the first place with spoofed IPs since the attacker already has the ability to spoof. In my experience, most often case of seeing these is when some poor old irc server is getting synflooded and you see a gazillion RST's from irc.blah.ru:6667 Is this article available online? I would be interested to see if it offered any other insights. -- Chris Green <cmg () uab edu> Laugh and the world laughs with you, snore and you sleep alone. _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- spoof detection? Sheahan, Paul (PCLN-NW) (Nov 13)
- Re: spoof detection? Chris Green (Nov 13)
- Re: spoof detection? Martin Forest (Nov 13)