To clarify, what I intended to say was if you filter all the IP addresses that do not belong to you from the Ethernet side of your routers outgoing traffic. The problems with spoofed or bogus IP addresses coming from your net blocks go away. If all Internet connected entities did this then this would make it possible to find and get the systems administrators to have the zombies patched failing that the zombie machines could be null routed. This would also assist in tracking down hackers, port scanners, and other criminal types who currently have free reign over your network with spoofed addresses. Bill Larson Network Administrator , Compu-Net Enterprises Local: (931) 920-0043 Toll free: (877) 920-1429 ----- Original Message ----- From: "Rob Thomas" <robt@cymru.com> To: <nanog@merit.edu> Sent: Thursday, July 12, 2001 12:03 PM Subject: Re: DDOS prevention offensive.
] Discuss the effect that wide spread filtering against spoofed ] addresses would have on the current number of DDOS attacks.
I performed a statistical analysis of a collection of log files from one oft-targeted site. The data therein revealed that 68% of all the naughty packets contained obviously bogon source addresses (e.g. 127/8).
I wouldn't extrapolate this analysis to fit all sites. I see more than enough DoS attacks were the source is not spoofed. I do think such filtering would go a long way towards mitigating DDoS attacks.
-- Rob Thomas http://www.cymru.com/~robt cmn_err(CE_PANIC, "Out of coffee...");