netdev - Re: Something hitting my total number of connections to the server

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAA5aLPgekZJgsZV-MAD+F+ggUugQkz12D9Ef=kbP9Ev=Q1QsDw@mail.gmail.com>
Date:   Wed, 16 Aug 2017 10:18:08 +0530
From:   Akshat Kakkar <akshat.1984@...il.com>
To:     netdev <netdev@...r.kernel.org>
Subject: Re: Something hitting my total number of connections to the server

On Mon, Aug 14, 2017 at 2:37 PM, Akshat Kakkar <akshat.1984@...il.com> wrote:
> I have centos 7.3 (Kernel 3.10) running on a server with 128GB RAM and
> 2 x 10 Core Xeon Processor.
> I have hosted a webserver on it and enabled ssh for remote maintenance.
> Previously it was running on Centos 6.3.
> After upgrading to CentOS 7.3, occasionally (probably when number of
> hits are more on the server), I am not able to create new connections
> (neither on web nor on ssh). Existing connections keeps on running
> fine.
>
> I did packet capturing using tcpdump to understand if its some
> intermediate network issue.
> What I found was the server is not replying for new SYN requests.
>
> So it's clear that its not at all application issue. Also, there are
> no logs in applications logs for any connections dropped, if any.
>
> I check my firewall rules if there is some rate limiting imposed.
> There is nothing in there.
>
> I check tc, if by mistake some rate limiting is imposed. There is
> nothing in there too.
>
> I have increased noOfFiles to 1000000 and other sysctl parameters, but
> the issue is still there.
>
> Has anybody experienced the same?
>
> How to go about? Anybody ... Please Help!!!

Its getting lonely out here. Anybody there ???