Chris Adams writes:

We appear to be under a distributed denial of service attack. We are receiving 7.5+ megabits per second of ICMP traffic (it looks like a smurf attack) from all over to a single address (one that was in our dialup pool). We've taken the IP out of our pool and are routing it to a separate interface with a computer just setup to capture traffic.

It isn't causing an immediate problem, since we've routed the traffic away, but what do we do next? We've been contacted by a couple of the people sending the ICMP replies complaining about us pinging them and told them about fixing distributed broadcast and they've said they'll look into it.

What do we do to track this down? We've got four upstreams and the traffic appears to be coming in all four; do we need to call all of them? Is there any kind of organization that can help coordinate this?

Thanks for any help you can give.

If Cisco equipment is involved, you can use the information at http://www.cisco.com/warp/public/707/22.html to characterize the attack and perhaps trace it. If you expect assistance from upstream, you'll have to characterize the attack as much as possible. Since the source addresses are usually spoofed, tracing the attack means that senior network engineers have to look at each link along the path, and it's going to be hard to get them interested if the traffic is not well defined. If you don't already know who to contact at each of your upstream providers, open a case with their support desk. Most major ISPs and NSPs have special teams that deal with attacks. If one of the upstreams (or other sources) is a member of the Forum of Incident Response and Security Teams (FIRST), you can look up the specific response team's contact info at http://www.first.org/. There's more info on mitigating DDoS attacks on the Cisco Security Advisories page, http://www.cisco.com/warp/public/707/advisory.html. If you need further help, you can contact the Cisco TAC. If it's a bona-fide emergency, you can engage our group, the Cisco Product Security Incident Response Team, to assist. Jim -- Jim Duncan, Product Security Incident Manager, Cisco Systems, Inc. <http://www.cisco.com/warp/public/707/sec_incident_response.shtml> E-mail: <jnduncan@cisco.com> Phone(Direct/FAX): +1 919 392 6209