netdev - Re: inet_hash_connect: source port allocation

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Message-ID: <1291056363.3435.1338.camel@edumazet-laptop>
Date:	Mon, 29 Nov 2010 19:46:03 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	John Haxby <john.haxby@...cle.com>
Cc:	NetDev <netdev@...r.kernel.org>,
	Stephen Hemminger <shemminger@...tta.com>
Subject: Re: inet_hash_connect: source port allocation

Le lundi 29 novembre 2010 à 18:29 +0000, John Haxby a écrit :

> Sorry,  I think I phrased my question badly.
> 
> inet_csk_get_port() starts its search for a free port with
> 
>      smallest_rover = rover = net_random() % remaining + low;
> 
> whereas __inet_hash_connect() basically misses out that call to 
> net_random() so you get a predictable port number.
> 
> Is there any good reason why that is the case?
> 

It seems random select was done at bind() time only in commit
6df716340da3a6f ([TCP/DCCP]: Randomize port selection)

It probably should be done in autobind too.



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