lots of connections in SYN_RECV state

[Puneet Agarwal]

nslookup does not give any result on those IP addresses.
So not able to figure out who is causing this.

Is there a way to check the reason, why they do not answer to the SYN-ACK's?

Thanks and Regards
Puneet

----------------------------------------
> Date: Thu, 6 Nov 2014 15:30:46 +0100
> From: me at sillymon.ch
> To: puneet.agr at outlook.com
> CC: kernelnewbies at kernelnewbies.org
> Subject: Re: lots of connections in SYN_RECV state
>
> Hi
>
> Am 2014-11-06 14:27, schrieb Puneet Agarwal:
>> I have a couple of servers, for the past few days I am seeing lots of
>> connections in SYN_RECV state in netstat commands output.
>
> This *could* be the result of a SYN-flood attack on your server.
>
>
>> Is there a solution to this problem?
>
> The Wikipedia page mentions some countermeasures (if it indeed is an
> attack and not a networking stack issue).
>
> http://en.wikipedia.org/wiki/SYN_flood
>
> Maybe you could check from which IP addresses these SYNs come from and
> investigate why they do not answer to the SYN-ACK request of your
> server.
>
>
> Cheers,
>
> Silvan