I use linux kernel 2.6. I have enabled SYN cookies already. But that does not seem to solve the problem. Overall request latency is very high with these many half open connections. Thanks and Regards Puneet ---------------------------------------- > Subject: Re: lots of connections in SYN_RECV state > From: dave.jing.tian@xxxxxxxxx > Date: Fri, 7 Nov 2014 23:49:35 +0800 > CC: puneet.agr@xxxxxxxxxxx; kernelnewbies@xxxxxxxxxxxxxxxxx > To: me@xxxxxxxxxxx > > Latest kernel provides a TCP SYN Cookie feature to defense from SYN flooding. > > -daveti > > >> On Nov 6, 2014, at 11:58 PM, Silvan Jegen <me@xxxxxxxxxxx> wrote: >> >> 2014-11-06 16:15,Puneet Agarwal: >>> Is there a way to check the reason, why they do not answer to the >>> SYN-ACK's? >> >> I don't think so. After all, they just don't answer and they won't tell >> you why (AFAIK there is no way to ask them why either)... >> >> You could try to check for patterns in the incoming IP addresses to see >> from how many different places these connections are being made. I think >> that way it should be possible to figure out from which geographic >> location these problematic connections are coming from as well. What you >> would do with these findings I am not sure though. >> >> If these connection negatively impact the performance of your servers >> you should definitely look into to countermeasures mentioned in the RFC >> here. >> >> http://tools.ietf.org/html/rfc4987 >> >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies@xxxxxxxxxxxxxxxxx >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
