linux-kernel - Possibility to adjust the only-root-can-bind-to-port-under-1024 limit

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Message-ID: <4742B3A3.2050103@univits.com>
Date:	Tue, 20 Nov 2007 11:14:59 +0100
From:	Mikael Ståldal 
	<mikael.staldal-ingen-reklam@...vits.com>
To:	linux-kernel@...r.kernel.org
Subject: Possibility to adjust the only-root-can-bind-to-port-under-1024 limit

In Linux you have to be root in order to listen to TCP or UDP ports below 1024 (the 
well-known ports). As far as I know, this limit is hardcoded in the kernel.

In some cases, this limit do more harm than good, so it would be nice to be able to adjust it.

FreeBSD have a pair of sysctl parameters allowing you to adjust (or effectively remove) this 
  limit, net.inet.ip.portrange.reservedlow and net.inet.ip.portrange.reservedhigh. It would 
be nice if something similar to net.inet.ip.portrange.reservedhigh was implemented in Linux 
(with default value 1023).

I have no patch for this, since I have never done any kernel hacking before. But it seems 
like it should be easy to implement by replacing the PROT_SOCK constant with 
net.inet.ip.portrange.reservedhigh + 1.

(See my blog post for a more elaborate discussion about this:
http://www.staldal.nu/tech/2007/10/31/why-can-only-root-listen-to-ports-below-1024/)

/Mikael

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