Subject: Re: Lost network connectivity in 4.0.x

From: Ken Moffat <[email-masked]>
Date: Thu, 28 May 2015 17:11:19 +0100

On Thu, May 28, 2015 at 03:41:49PM +0100, Ken Moffat wrote:
> On Wed, May 27, 2015 at 10:53:00PM -0700, Cong Wang wrote:
> > (Please always Cc netdev for networking bugs.)
> > 
Sorry, didn't spot that.  But anyway
> 
> > For example:
> > 
> > 1) What is your network setup? iptables? routes? etc.
> > 
> I'm using iptables.  Ah, yes - it started dropping packets around
> the time I last had a problem:
> 
> May 27 00:48:26 ac4tv dhclient: DHCPREQUEST on eth0 to 192.168.7.254
> port 67
> May 27 00:48:27 ac4tv dhclient: DHCPACK from 192.168.7.254
> May 27 00:48:27 ac4tv dhclient: bound to 192.168.7.152 -- renewal in
> 1787 seconds.
> 
>  That address came from my router, and I had been getting the same
> address for an hour, tbut then the dropped packet messages start
> appearing - they are for a different address, one that would have
> been offered by my server:
> 
Now that I've had time to think about this and look a bit more
deeply, I can see that at one point I got a lease from my server,
but then after a random length of time the client tried to renew and
got a lease from the router.  Some time after that, it failed
because iptables rejected the nfs packets because they were "not for
me".

So, not a kernel problem, and the reason I'm (now) seeing this on
4.0+ kernels is that I have not recently booted a system with an old
(3.19 or earlier) kernel and kept it running for a long time.

Thanks again, sorry to waste everybody's bandwidth.

ĸen
-- 
Nanny Ogg usually went to bed early. After all, she was an old lady.
Sometimes she went to bed as early as 6 a.m.