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From: Willy Tarreau <>
To: Alan Cox <>
Cc: Nebojsa Miljanovic <>,, "Kittlitz,
	Edward (Ned)" <>,, "Polhemus,
	William (Bart)" <>
Subject: Re: SO_REUSEADDR not allowing server and client to use same port
Date: Thu, 28 Feb 2008 21:41:47 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20080228201926.558c4e7c@core>

On Thu, Feb 28, 2008 at 08:19:26PM +0000, Alan Cox wrote:
> > Currently, Linux does not allow reuse of same local port for both TCP server and
> > TCP client. I understand that there may be a need to prevent two servers from
> Think about what happens for simultaneous connect (that obscure little
> corner of the tcp/ip spec). Now think about what it means for security.
> ALan

exactly. That's why I think that requiring the server to explicitly allow
socket reuse is mandatory. On another side of the problem, I really think
that we should make the simultaneous connect configurable. I've been patching
all of my own 2.4 kernels for a while to add a config option to turn it off
because there is a real security issue with this on. At least for mainline,
it should be a sysctl. No stateful firewall I know supports the feature, so
legitimate uses of this feature are likely very very small.


  reply	other threads:[~2008-02-28 20:42 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-28 18:15 Nebojsa Miljanovic
2008-02-28 18:30 ` Phil Oester
2008-02-28 20:19 ` Alan Cox
2008-02-28 20:41   ` Willy Tarreau [this message]
2008-03-13 19:18   ` Nebojsa Miljanovic
2008-03-15 13:34     ` Alan Cox
2008-03-17 16:43       ` Nebojsa Miljanovic
2008-03-17 17:30         ` Alan Cox
2008-03-17 18:17           ` Nebojsa Miljanovic
2008-03-18  5:48             ` Willy Tarreau
2008-02-28 20:36 ` Willy Tarreau
2008-02-28 20:44   ` Nebojsa Miljanovic

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