Nginx TCP Delays

Payam Chychi pchychi at
Tue Sep 22 10:18:06 MSD 2009

On Mon, Sep 21, 2009 at 9:25 PM, Khalid Shaikh
<khalid.j.shaikh at> wrote:
> Team,
> I've applied almost every suggestion given to me and still cannot resolve
> the delays.
> Is there anyone whom is willing to log into the server and take a look?  I
> can compensate if needed!
> Please email me!
> Active connections: 7506
> server accepts handled requests
>  173367 173367 443669
> Reading: 82 Writing: 1721 Waiting: 5703
>      21.03 seconds
> Best,
> Khalid
> khalid.j.shaikh at

does not seem to be an nginx issue, server side issue due to high
amount of connections being tracked by nf_conntrack aka iptables
modifying that value to something of power of 2 will solve the
issue... you can set the number  safely around 1048576 as well as your
hash bucket size

Active connections: 12558
server accepts handled requests
 192560 192560 747535
Reading: 152 Writing: 2661 Waiting: 9745

also enabling linux syncookie helps a lot so you dont have to deal
with stupid bogus traffic :)
[201926.711051] possible SYN flooding on port 80. Sending cookies.


Payam Tarverdyan Chychi
Network Security Specialist / Network Engineer

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