netdev - Re: ipv6 issues after an DDoS for kernel 4.6.3

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: <1467987260.30694.2.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Fri, 08 Jul 2016 16:14:20 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Toralf Förster <toralf.foerster@....de>
Cc:	netdev@...r.kernel.org
Subject: Re: ipv6 issues after an DDoS for kernel 4.6.3

On Fri, 2016-07-08 at 15:51 +0200, Toralf Förster wrote:
> I do run a 4.6.3 hardened Gentoo kernel at a commodity i7 server. A
> DDoS with about 300 MBit/sec over 5 mins resulted an issue for ipv6 at
> that system.
> 
> The IPv6 monitoring from my ISP told my that the to be monitored
> services (80, 443, 52222) weren't reachable any longer at ipv6 (at
> ipv4 there was no issue). Restarting the NIC brought back green lights
> for the services at the ipv6 ports too.

Hard to tell without knowing DDOS details, but IPv6 lacks some
scalability improvements found in IPv4.

IPv4 no longer has a routing cache, but IPv6 still has one.

Are you sure conntrack is needed at all ?