netdev - Re: IPv4 route cache DOS attack

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Date:	Tue, 27 Nov 2012 17:34:09 -0800
From:	叶雨飞 <sunyucong@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: IPv4 route cache DOS attack

Thanks!!! it works, after flushing cache it stays 0.

On Tue, Nov 27, 2012 at 5:01 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Tue, 2012-11-27 at 15:15 -0800, 叶雨飞 wrote:
>> Hi,
>>
>> I have a linux router running kernel 3.2  that receive public ingress
>> packets and route them through an GRE tunnel, return packets don't go
>> through it
>>
>> I've recently faced a serious issue with the route cache,  when the
>> router received spoofed source , the route cache will quickly get
>> exhausted (depending on the size of it) and soon the ip dst cache
>> overflow will be printed and network subsystem will hang until
>> restarted.
>>
>> So, my question is, how can I turn off the route cache without
>> recompile the kernel or adding the  patch for removal  in 3.7?  I
>> tried to set
>>
>> echo 0 > /proc/sys/net/ipv4/route/max_size but that has no effect at all.
>>
>> And if some one can share some insight on why when dst cache
>> overflows, the network subsystem hangs, it would be great.
>
> echo -1 >/proc/sys/net/ipv4/rt_cache_rebuild_count
>
>
>
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