Security Basics mailing list archives
Re: TCP Syn Flooding
From: "Anders Reed Mohn" <anders_rm () utepils com>
Date: Mon, 17 Feb 2003 23:09:32 +0100
I received this message a few times yesterday after I installed the box: Fri, 02/14/2003 20:35:01 - TCP connection dropped - Source:205.138.3.201, 80, WAN - Destination:69.2.167.25, 20306, LAN - 'TCP:Syn Flooding' End of Log ---------- What should I make of this?
Not sure, Tim, but I'll make a guess. Is there a website at 205.138.3.201 that you've visited? Now, the firewall will have reacted because this address sent one or more SYN packets that weren't expected. The target port for the SYN packet is a typical client port, and not a service, so it's probably not an attack of any sort. This is something that all firewalls log tons of after you've visited a web-site. I think the explanation is that when you _left_ the page, the TCP-connections to it were not closed. Thus, the remote server still thinks you are connected, and sends traffic to you. Your firewall, however, has already dropped the connection and therefore thinks this is illegitimate traffic. Cheers, Anders :)
Current thread:
- TCP Syn Flooding Tim Laureska (Feb 17)
- Re: TCP Syn Flooding Matt Thoene (Feb 17)
- Re: TCP Syn Flooding Ivan Hernandez (Feb 17)
- RE: TCP Syn Flooding Craig Searle (Feb 18)
- RE: TCP Syn Flooding Tim Laureska (Feb 18)
- RE: TCP Syn Flooding Craig Searle (Feb 18)
- RE: TCP Syn Flooding Tim Laureska (Feb 18)
- RE: TCP Syn Flooding Tim Laureska (Feb 18)
- Re: TCP Syn Flooding Anders Reed Mohn (Feb 18)
- Re: TCP Syn Flooding neopara (Feb 18)
- RE: TCP Syn Flooding Tim Laureska (Feb 19)
- RE: TCP Syn Flooding neopara (Feb 20)
- Windows auditing eric (Feb 22)
- RE: TCP Syn Flooding Tim Laureska (Feb 19)
- <Possible follow-ups>
- RE: TCP Syn Flooding Michael Parker (Feb 17)
- RE: TCP Syn Flooding Anomaly (Feb 18)
- Re: TCP Syn Flooding Chris Berry (Feb 17)
- re: TCP Syn Flooding H C (Feb 18)
- RE: TCP Syn Flooding Michael Parker (Feb 18)