Hi,

We have the same problem.

Attacks are random and with many source IPs (botnets). Therefore it is harder to have an automatic system to block source IPs. Our kind of "workaround" was to increase the request_list size from the default 1024 to a higher number and to enable jostle-timeout to something like 4sec. Therefore requests do not stay too long in the request_list once the box is under load. Manual iptables rules are not maintainable, we only manually block IPs for the biggest hitter. I agree what we are doing is _not_ a fix to the problem because we just allocated more resources to deal with the junk, but jostle-timeout definetely helps. I asked about it almost a year ago on this mailing-list.

Subject: Unbound DDoS / reflexion attack counter-measure ?
Date: 30/05/14 22:20

> Any solution that can be shared ?
By trying to find my previous post, I actually realised that I missed Daisuke's email.

Subject: "a mitigation against random subdomain attack"
Date: 24/03/15

His solution: https://github.com/hdais/unbound-bloomfilter

I will test it when I have a bit of time.

Thomas
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