more thoughts on the Code Red DDoS attacks. this advice has to do with Cisco routers. Chuck -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Bill Woodcock Sent: Thursday, July 19, 2001 8:30 PM To: [EMAIL PROTECTED] Subject: Re: Code Red > Reports from our monitoring systems saw the CPU usage jump by somewhere > between 150-200% for our core routers today I just got off the phone with the TAC about this, and received the following _preliminary_ advice: 1) If it's not enabled, turn on CEF, to move some of the packet-forwarding load off the processor and into hardware. For some reason, a lot of this traffic is being process-switched, as evidenced by high "IP Input" cpu loads. 2) If you can, put in an ACL which prohibits port-80 traffic destined _to the interfaces of the router itself_. Since the destination IP addresses of the packets which constitute the attack itself are random, many of them will be addressed to your routers, rather than to hosts, and those will _always_ be process switched, if they're not blocked by an inbound ACL. It goes without saying that you should have a "no http server" line in any production router. -Bill Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=13056&t=13056 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
