Graeme Fowler <graeme@graemef.net> writes:
I've been seeing a lot of noise from the latter two addresses after switching on query logging (and finishing an application of Team Cymru's excellent template) so I decided to DROP traffic from the addresses (with source port != 53) at the hosts in question.
Well, blow me down if they didn't completely stop talking to me. Four dropped packets each, and they've gone away.
Something smells "not quite right" here - if the traffic is spoofed, and my "Refused" responses have been flying right back to the *real* IP addresses, how are the spoofing hosts to know that I'm dropping the traffic?
Did you filter *only* 66.230.128.15/66.230.160.1, or are you dropping traffic from other sources too? Looks like some of the other source addresses are controlled by the DOSers. Possibly used to detect filters? These clients may look similar to the DOS attack, but there are subtle differences: Jan 18 05:08:33 canardo named[32046]: client 211.72.249.201#29656: view external: query (cache) './NS/IN' denied Jan 18 05:08:33 canardo named[32046]: client 211.72.249.201#29656: view external: query (cache) './NS/IN' denied Jan 18 05:08:34 canardo named[32046]: client 211.72.249.201#29656: view external: query (cache) './NS/IN' denied Jan 18 05:47:00 canardo named[32046]: client 211.72.249.201#29662: view external: query (cache) './NS/IN' denied Jan 18 05:47:01 canardo named[32046]: client 211.72.249.201#29662: view external: query (cache) './NS/IN' denied Jan 18 05:47:01 canardo named[32046]: client 211.72.249.201#29662: view external: query (cache) './NS/IN' denied Jan 18 06:25:22 canardo named[32046]: client 211.72.249.201#29664: view external: query (cache) './NS/IN' denied Jan 18 06:25:22 canardo named[32046]: client 211.72.249.201#29664: view external: query (cache) './NS/IN' denied Jan 18 06:25:23 canardo named[32046]: client 211.72.249.201#29664: view external: query (cache) './NS/IN' denied Jan 18 07:03:41 canardo named[32046]: client 211.72.249.201#29667: view external: query (cache) './NS/IN' denied Jan 18 07:03:41 canardo named[32046]: client 211.72.249.201#29667: view external: query (cache) './NS/IN' denied Jan 18 07:03:42 canardo named[32046]: client 211.72.249.201#29667: view external: query (cache) './NS/IN' denied Jan 18 07:42:08 canardo named[32046]: client 211.72.249.201#29670: view external: query (cache) './NS/IN' denied Jan 18 07:42:09 canardo named[32046]: client 211.72.249.201#29670: view external: query (cache) './NS/IN' denied Jan 18 07:42:09 canardo named[32046]: client 211.72.249.201#29670: view external: query (cache) './NS/IN' denied Jan 18 08:20:29 canardo named[32046]: client 211.72.249.201#29673: view external: query (cache) './NS/IN' denied Jan 18 08:20:29 canardo named[32046]: client 211.72.249.201#29673: view external: query (cache) './NS/IN' denied Jan 18 08:20:30 canardo named[32046]: client 211.72.249.201#29673: view external: query (cache) './NS/IN' denied Jan 18 08:58:50 canardo named[32046]: client 211.72.249.201#29678: view external: query (cache) './NS/IN' denied Jan 18 08:58:51 canardo named[32046]: client 211.72.249.201#29678: view external: query (cache) './NS/IN' denied Jan 18 08:58:51 canardo named[32046]: client 211.72.249.201#29678: view external: query (cache) './NS/IN' denied Jan 18 09:37:12 canardo named[32046]: client 211.72.249.201#29679: view external: query (cache) './NS/IN' denied Jan 18 09:37:12 canardo named[32046]: client 211.72.249.201#29679: view external: query (cache) './NS/IN' denied Jan 18 09:37:13 canardo named[32046]: client 211.72.249.201#29679: view external: query (cache) './NS/IN' denied Jan 20 07:02:51 canardo named[32046]: client 213.61.92.192#46716: view external: query (cache) './NS/IN' denied Jan 20 07:02:51 canardo named[32046]: client 213.61.92.192#46716: view external: query (cache) './NS/IN' denied Jan 20 07:02:51 canardo named[32046]: client 213.61.92.192#46716: view external: query (cache) './NS/IN' denied Jan 20 07:41:21 canardo named[32046]: client 213.61.92.192#46752: view external: query (cache) './NS/IN' denied Jan 20 07:41:21 canardo named[32046]: client 213.61.92.192#46752: view external: query (cache) './NS/IN' denied Jan 20 07:41:21 canardo named[32046]: client 213.61.92.192#46752: view external: query (cache) './NS/IN' denied Jan 20 08:19:46 canardo named[32046]: client 213.61.92.192#46785: view external: query (cache) './NS/IN' denied Jan 20 08:19:46 canardo named[32046]: client 213.61.92.192#46785: view external: query (cache) './NS/IN' denied Jan 20 08:19:46 canardo named[32046]: client 213.61.92.192#46785: view external: query (cache) './NS/IN' denied Jan 20 08:58:12 canardo named[32046]: client 213.61.92.192#46808: view external: query (cache) './NS/IN' denied Jan 20 08:58:12 canardo named[32046]: client 213.61.92.192#46808: view external: query (cache) './NS/IN' denied Jan 20 08:58:12 canardo named[32046]: client 213.61.92.192#46808: view external: query (cache) './NS/IN' denied Jan 20 09:36:34 canardo named[32046]: client 213.61.92.192#46833: view external: query (cache) './NS/IN' denied Jan 20 09:36:34 canardo named[32046]: client 213.61.92.192#46833: view external: query (cache) './NS/IN' denied Jan 20 09:36:34 canardo named[32046]: client 213.61.92.192#46833: view external: query (cache) './NS/IN' denied Jan 20 10:14:58 canardo named[32046]: client 213.61.92.192#46858: view external: query (cache) './NS/IN' denied Jan 20 10:14:58 canardo named[32046]: client 213.61.92.192#46858: view external: query (cache) './NS/IN' denied Jan 20 10:14:58 canardo named[32046]: client 213.61.92.192#46858: view external: query (cache) './NS/IN' denied Jan 22 06:27:28 canardo named[32046]: client 66.238.93.161#34373: view external: query (cache) './NS/IN' denied Jan 22 06:27:28 canardo named[32046]: client 66.238.93.161#34373: view external: query (cache) './NS/IN' denied Jan 22 06:27:28 canardo named[32046]: client 66.238.93.161#34373: view external: query (cache) './NS/IN' denied Jan 22 07:05:55 canardo named[32046]: client 66.238.93.161#34420: view external: query (cache) './NS/IN' denied Jan 22 07:05:55 canardo named[32046]: client 66.238.93.161#34420: view external: query (cache) './NS/IN' denied Jan 22 07:05:55 canardo named[32046]: client 66.238.93.161#34420: view external: query (cache) './NS/IN' denied Jan 22 07:44:20 canardo named[32046]: client 66.238.93.161#34473: view external: query (cache) './NS/IN' denied Jan 22 07:44:20 canardo named[32046]: client 66.238.93.161#34473: view external: query (cache) './NS/IN' denied Jan 22 07:44:21 canardo named[32046]: client 66.238.93.161#34473: view external: query (cache) './NS/IN' denied Jan 22 08:22:38 canardo named[32046]: client 66.238.93.161#34503: view external: query (cache) './NS/IN' denied Jan 22 08:22:38 canardo named[32046]: client 66.238.93.161#34503: view external: query (cache) './NS/IN' denied Jan 22 08:22:38 canardo named[32046]: client 66.238.93.161#34503: view external: query (cache) './NS/IN' denied Jan 22 09:00:56 canardo named[32046]: client 66.238.93.161#34540: view external: query (cache) './NS/IN' denied Jan 22 09:00:56 canardo named[32046]: client 66.238.93.161#34540: view external: query (cache) './NS/IN' denied Jan 22 09:00:56 canardo named[32046]: client 66.238.93.161#34540: view external: query (cache) './NS/IN' denied Jan 22 09:39:20 canardo named[32046]: client 66.238.93.161#34574: view external: query (cache) './NS/IN' denied Jan 22 09:39:21 canardo named[32046]: client 66.238.93.161#34574: view external: query (cache) './NS/IN' denied Jan 22 09:39:21 canardo named[32046]: client 66.238.93.161#34574: view external: query (cache) './NS/IN' denied Notice the pattern: 3 probes every 38 minutes Each probe from the same source port Source port increases slowly and steadily This looks like some application actually waiting for a response. The slow source port change is probably an indication that this client only tests a small number of DNS servers. I guess that this client is either one of the many bots used to send the spoofed requests, or maybe a bot not allowed to spoof its source and therefore used for other purposes. In any case, I assume that other DNS servers may see such control sessions coming from other addresses. These 3 clients started probing my DNS server almost simultaneously on January 8th: Jan 8 19:33:52 canardo named[26496]: client 213.61.92.192#31195: view external: query (cache) './NS/IN' denied Jan 8 19:33:52 canardo named[26496]: client 213.61.92.192#31195: view external: query (cache) './NS/IN' denied Jan 8 19:33:52 canardo named[26496]: client 213.61.92.192#31195: view external: query (cache) './NS/IN' denied Jan 8 19:36:29 canardo named[26496]: client 66.238.93.161#11299: view external: query (cache) './NS/IN' denied Jan 8 19:36:29 canardo named[26496]: client 66.238.93.161#11299: view external: query (cache) './NS/IN' denied Jan 8 19:36:30 canardo named[26496]: client 66.238.93.161#11299: view external: query (cache) './NS/IN' denied Jan 8 19:37:47 canardo named[26496]: client 211.72.249.201#29112: view external: query (cache) './NS/IN' denied Jan 8 19:37:47 canardo named[26496]: client 211.72.249.201#29112: view external: query (cache) './NS/IN' denied Jan 8 19:37:47 canardo named[26496]: client 211.72.249.201#29112: view external: query (cache) './NS/IN' denied Maybe preparing for the attack on ISPrime? I didn't start receiving spoofed requests from 66.230.128.15/66.230.160.1 before January 20th I just tried filtering the probing addresses. This made the probing stop immediately after dropping a set of 3 probes. But the spoofed requests continuted at the same rate as before, so this does not support my theory. However, I believe it would be too much of a coincidence if there isn't some connection between the probing and the DOS attack. It would be interesting to hear if others see similar probing. Bjørn