netdev - Re: binding UDP port 0 with SO

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Date:	Wed, 01 Aug 2012 21:02:56 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"Tobias S. Josefowitz" <t.josefowitz@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: binding UDP port 0 with SO_REUSEADDR

On Wed, 2012-08-01 at 13:36 +0200, Tobias S. Josefowitz wrote:
> Hey all,
> 
> I recently noticed that binding UDP port 0 with SO_REUSEADDR yields
> unexpected results for me - the kernel occasionally gives out UDP
> ports used by other processes, if they were bound with SO_REUSEADDR,
> too.
> 
> I did some digging, it seems that
> f24d43c07e208372aa3d3bff419afbf43ba87698 introduced this behaviour.
> I'm not at all sure if this could/should be called a bug, but I need
> to say, it was severly unexpected at my side, and that probably goes
> for others, too.
> 
> Just bringing this to your attention, I have no suggestions on it whatsoever.

And why are you using SO_REUSEADDR on UDP unicast sockets ?

I mean, this is exactly saying " By using this REUSEADDR, I am allowing
this port being used by another process, even from another user"



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