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Re: [han.holl@pobox.com] libc/1172: rresvport should avoid well known ports
- To: Thorsten Kukuk <kukuk@suse.de>
- Subject: Re: [han.holl@pobox.com] libc/1172: rresvport should avoid well known ports
- From: Andreas Jaeger <aj@arthur.rhein-neckar.de>
- Date: 25 Jun 1999 20:39:37 +0200
- Cc: libc-alpha Mailinglist <libc-alpha@sourceware.cygnus.com>, han.holl@pobox.com
- References: <u83dzgdxqd.fsf@arthur.rhein-neckar.de> <19990625194659.A3312@Wotan.suse.de>
>>>>> Thorsten Kukuk writes:
Thorsten> Hello,
Thorsten> On Fri, Jun 25, Andreas Jaeger wrote:
>>
>> We've received the appended bug report. I understand the problem the
>> user has but I'm not sure that we should follow the suggestion.
>>
>> Could you please comments on this?
Thorsten> I would say programs which uses fixed port numbers between 512 - 1023 are
Thorsten> broken. For this, we have the numbers less 512.
Thorsten> 512 - 1023 are reserved for dynamically used privileged ports.
Check RFC1700, the ports are reserved until 1023 - and there're some
well known programs in the range like kerberos,syslog,talk.
Andreas
P.S. Some exceperts from RFC1700
WELL KNOWN PORT NUMBERS
The Well Known Ports are controlled and assigned by the IANA and on
most systems can only be used by system (or root) processes or by
programs executed by privileged users.
Ports are used in the TCP [RFC793] to name the ends of logical
connections which carry long term conversations. For the purpose of
providing services to unknown callers, a service contact port is
defined. This list specifies the port used by the server process as
its contact port. The contact port is sometimes called the
"well-known port".
To the extent possible, these same port assignments are used with the
UDP [RFC768].
The assigned ports use a small portion of the possible port numbers.
For many years the assigned ports were in the range 0-255. Recently,
the range for assigned ports managed by the IANA has been expanded to
the range 0-1023.
Port Assignments:
[...]
login 513/tcp remote login a la telnet;
# automatic authentication performed
# based on priviledged port numbers
# and distributed data bases which
# identify "authentication domains"
who 513/udp maintains data bases showing who's
# logged in to machines on a local
# net and the load average of the
# machine
cmd 514/tcp like exec, but automatic
# authentication is performed as for
# login server
syslog 514/udp
printer 515/tcp spooler
printer 515/udp spooler
# 516/tcp Unassigned
# 516/udp Unassigned
talk 517/tcp like tenex link, but across
# machine - unfortunately, doesn't
# use link protocol (this is actually
# just a rendezvous port from which a
# tcp connection is established)
talk 517/udp like tenex link, but across
# machine - unfortunately, doesn't
# use link protocol (this is actually
# just a rendezvous port from which a
tcp connection is established)
ntalk 518/tcp
ntalk 518/udp
utime 519/tcp unixtime
utime 519/udp unixtime
efs 520/tcp extended file name server
router 520/udp local routing process (on site);
# uses variant of Xerox NS routing
# information protocol
# 521-524 Unassigned
timed 525/tcp timeserver
timed 525/udp timeserver
[...]
mdbs_daemon 800/tcp
mdbs_daemon 800/udp
device 801/tcp
device 801/udp
xtreelic 996/tcp Central Point Software
xtreelic 996/udp Central Point Software
# Dale Cabell <dacabell@smtp.xtree.com>
maitrd 997/tcp
maitrd 997/udp
busboy 998/tcp
puparp 998/udp
garcon 999/tcp
applix 999/udp Applix ac
puprouter 999/tcp
puprouter 999/udp
cadlock 1000/tcp
ock 1000/udp
1023/tcp Reserved
1024/udp Reserved
# IANA <iana@isi.edu>
--
Andreas Jaeger aj@arthur.rhein-neckar.de jaeger@informatik.uni-kl.de
for pgp-key finger ajaeger@aixd1.rhrk.uni-kl.de