David Nolan wrote:
<snip>
(*): For anyone who doesn't know, URPF is essentially a way to do
automatic acls, comparing the source IP of on an incoming packet to the
routing table to verify the packet should have come from this
interface. With the right hardware this is significantly cheaper then
acl processing. And its certainly easier to maintain. And by injecting
a /32 null route into the route table you can cause a host's local
router to start discarding all traffic from that IP.
<snip sig>
Yeah, but it's not near as fun as dynamic acls updated via a script
monitoring flow logs in real-time. It's definitely easier to implement,
though.
For people utilizing RBE/dhcp combo on Cisco routers, it is also
possible to just remove the /32 route that was dynamically created which
will kill traffic until the customer requests dhcp again, which will by
that time place them in the quarantine. One advantage to temp route
removal is that it requires no cleanup. Just make sure you don't wipe
out your permanent static routes.
-Jack