That's Odd, because with my experience with it, the destination (for example, irc.lightning.net) gets the committed access rate you set, however, the pipes are still flooded and connectivity to the outside world is poor to nil. You would still have to agree that by having the upstream providors set the rate-limits is the safest and most effective interim solution until something can be done permanently about this oh so wonderful attack :-) Alex Bligh wrote:
My limited experience is that if you run CEF on the interface concerned, life is bearable. If you don't, it isn't. If you run < 11.1.17?? CA where fast discards and routes to null0 were introduced, life is disastrous.
Alex Bligh GX Networks (formerly Xara Networks)
Alex Bligh wrote:
servers, one for the outside world and one for our customers only. The public server will be connected via a T1 to a smurf tracing friendly transit provider for external connectivity. This T1 will be used for this
OK, tell me where this falls down. Set up two IP addresses for your IRC server on the same machine. On the router upstream from the machine, allow only your customers to connect to one IP address, and anyone else to connect to the other IP. Now go to your border routers, enable CEF and configure something like:
! impose limits access-list 100 permit ip any host public-irc.my.net access-list 100 permit ip any host public-irc.my.net access-list 101 deny ip any host private-irc.my.net ! i/f config for borders interface myinterface ip access-group 101 in rate-limit input access-group 102 512000 512000 512000 conform-action transmit exceed-action drop
Effectively this means that if your public IP gets smurfed, it's b/w usage internally on your network is limited. If your private IP gets smurfed, it all gets dropped (thinking about it if you made exceptions for IRC peering you could do the whole thing on one IP if your customers never use border router i/fs).
If you are paying per bit, you'll still pay for smurfs, but they'll have to be 45Mb/s in size to cause any real damage. You'll probably find BGP flapping up and down as your T1 saturates is more of a problem.
-- Alex Bligh GX Networks (formerly Xara Networks)
-- \\|// -(@ @)- ==========================oOO==(_)==OOo================================= Steven Nash uin: 9021398 Cisco Certified Design Specialist em: snash@lightning.net Network Engineer Lightning Internet Services LLC http://www.lightning.net -=+===================================================================+-
-- \\|// -(@ @)- ==========================oOO==(_)==OOo================================= Steven Nash uin: 9021398 Cisco Certified Design Specialist em: snash@lightning.net Network Engineer Lightning Internet Services LLC http://www.lightning.net -=+===================================================================+-