Which UDP Port to Use?
Johannes Franken
jfranken at jfranken.de
Sat Dec 17 20:32:27 UTC 2005
* Michael D. Berger <m.d.berger at ieee.org> [2005-12-17 19:53 +0100]:
> On RH-E-WS-4 I need to open a UDP socket for internal use. How shall
> I select the port number?
Rules for selecting an UDP port:
- UDP port numbers can be between 1 and 65535.
- For listening on ports <1024, your daemon needs to run with UID 0
(root user).
- As long as you're not listening on a broadcast IP, there must be no
other program using this port (that is, neither listening or as
source-port)
- Run "netstat -puna" to see which UDP ports are aready in use on your
machine.
- Download http://www.iana.org/assignments/port-numbers and look for
"Unassigned" ports, to avoid conflicts with services you might install
later.
- Better choose a port outside the range given in
/proc/sys/net/ipv4/ip_local_port_range, because these ports might
already be in use as source-ports by other programs on later boots.
--
Johannes Franken
Red Hat Certfied Engineer
mailto:jfranken at jfranken.de
http://www.jfranken.de/
More information about the redhat-list
mailing list