On Feb 4, 7:44pm, [email protected] ([email protected]) wrote: -- Subject: Re: DoS attack against TCP services
| Now the server has over 5000 TIME_WAIT connections. | | netstat -a -n | grep TIME_WAIT | tcp 0 0 139.18.25.33.59256 198.6.1.83.53 TIME_WAIT | tcp 0 0 139.18.25.33.59257 77.222.50.250.53 TIME_WAIT | tcp 0 0 139.18.25.33.59258 193.232.128.6.53 TIME_WAIT | tcp 0 0 139.18.25.33.59259 78.104.145.37.53 TIME_WAIT | tcp 0 0 139.18.25.33.59260 192.5.6.30.53 TIME_WAIT | tcp 0 0 139.18.25.33.59261 192.41.162.30.53 TIME_WAIT | tcp 0 0 139.18.25.33.59262 192.35.51.30.53 TIME_WAIT | tcp 0 0 139.18.25.33.59263 192.43.172.30.53 TIME_WAIT | tcp 0 0 139.18.25.33.59264 202.12.27.33.53 TIME_WAIT | ... | | It seems to be a result of the named. lsof shows that the connections are | not owned by named. lsof doesn't show any of the TIME_WAIT connections. So | stopping and restarting named doesn't delete the connections. | | Any more things that could be interessing for a problem report? I'd start a tcpdump to record all traffic from your local machine going to port 53 on the appropriate interface... I'd also look at the open descriptors of the named process (although they should be closed at this time, since TIME_WAIT means closed on this side, and waiting for the 4 minutes to expire before killing the connection)... Also I'd record that information every minute or so to see how many connections are added and how many are going away. Perhaps there is some bug triggered in the tcp stack and somehow connections are not being GC'ed? christos
