[CentOS] [Fwd: How to listen port under 1024 with non-root user]

Rodrigo Barbosa rodrigob at darkover.org
Thu Jul 6 01:07:20 UTC 2006


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On Thu, Jul 06, 2006 at 08:56:17AM +0800, dxuranus wrote:
> I make a simple mail program which need listen port 25 and 110.but i
> found it's imposible , after searching with google i found non-root user
> can't listen port under 1024.at first i try a script(witch lauch my
> program) and use setuid but that still did't work.any way can handle
> this.
> Thanks for any help.

Yes, that is correct. It is impossible, on the Unix model, for a non-root
program to listen to a privileged port (<1024).

The best solution is for the program to start as root, bind to the
port, than lower its privileges using the setuid() family of functions.
I particularly enjoy setreuid().

- -- 
Rodrigo Barbosa
"Quid quid Latine dictum sit, altum viditur"
"Be excellent to each other ..." - Bill & Ted (Wyld Stallyns)

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