Aaron Dewell wrote:
On Thu, 25 Sep 2003, Eric A. Hall wrote:
I know you all have probably already thought of this, but can anyone think of a feasible way to run a RBL list that does not have a single point of failure? Or any attackable entry?
Easy. Have the master server only be reachable by replication partners through a VPN connection, and have dozens of secondaries advertising through multiple anycast addresses.
So why couldn't you follow this plan without the VPN and anycast? Have a couple of master servers totally unpublished (nobody except the secondaries know about it), then have dozens of secondaries that are the ones actually used (or AXFR'd off of). You can't attack all the secondaries at once if there are enough of them, and the master server is unknown (hopefully).
You could certainly improve on that system with a VPN, but the service is reasonable without it. Make your secondaries be volunteers who sign an agreement to never tell anyone what your master IP addresses are. If they get out, shift the master files to a secondary, notify the other secondaries by secure channels, and you're back in business.
Even better - Publish all the servers, nobody knows who the masters are of this list of N servers, and rotate it when needed or every so often.
I'd be a secondary/rotating master in that setup. I'm sure you'd get a bunch of volunteers.
All well an good until the DDoSer systematically DDoSes each secondary in order as has happened with SPEWS and SORBS. Further, what's the point of having a DNSbl if the blocked parties cannot get to the website to: 1/ Find out why they are blocked. 2/ Get delisted when they have fixed the issue. When it comes to SPEWS - that isn't so much of an issue, with SORBS it is the main part of the system. / Mat