|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: New Denial of Service Attack on Panix
>> Has someone come up with instructions on how to do source address >> filtering/verification for different brands of routers? It would be >> good if someone could put up a web page with complete instructions on >> how to do this. If this could be done quick enough we could possibly >> get the URL some publicity due to the current Panix attack. > >I would certainly publicize such a website. Although I think it would be >best if it was placed at some other site with info that ISP's should see >like perhaps www.ra.net. > >So far I've only seen Cisco filters posted. We still need to see >instructions for Livingston IRX, Bay, and Linux/FreeBSD ipfwadm Simple for Livingstons... create a filter "internet.out" Contents: three lines for each net block you have: permit 1.2.3.4/20 tcp permit 1.2.3.4/20 udp permit 1.2.3.4/20 icmp final line to log (optional) MUST COME AFTER permit list for netblocks: deny log The final line will have the router syslog a message any time someone tries to send from an address outside your blocks, as defined in the rest of the filter. This is optional. Keep in mind that the panix attack would probably have flooded your syslog machine's disk space with syslog info in this case. Hardening that is an issue for another day, however. Apply this to all outbound ports on your gateway IRX routers. You can do similar things with inbound ports on customer connections or other internal routers if you desire to start filtering earlier than your border gateway machines. For example, if 1.2.3.0/21 is your block for your St Louis hub and 2.3.11.0/24 and 2.3.22.0/26 are customer nets there, then the outbound interface for your St Louis IRX could have the following filter on its outbound interface(s): permit 1.2.3.0/21 tcp permit 1.2.3.0/21 udp permit 1.2.3.0/21 icmp permit 2.3.11.0/24 tcp permit 2.3.11.0/24 udp permit 2.3.11.0/24 icmp permit 2.3.22.0/26 tcp permit 2.3.22.0/26 udp permit 2.3.22.0/26 icmp deny log Alternatively you can filter on incoming ports with the same syntax. -george william herbert [email protected] Random Disclaimer time, since InterNIC asked me recently: I have not been a CRL employee for nearly 2 years. My opinions are of course my own. - - - - - - - - - - - - - - - - -
|