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SubjectISSUE: Linux bug/restriction prevents multicast participation
Bug report form (as suggested by the old mailing list FAQ)
Summary: A bug/misguided restriction in Linux prevents users from
participating in certain multicast video sessions.

Full description: Multicast standards prescribe that the port range
49152-65535 be used for video traffic. From my observations, Linux does not
allow user processes to use multicast sessions with ports 61000+, and
therefore Linux can not participate in many multicast video sessions. Since
unicast sockets can't bind to the port range either, I'm assuming that this
port range was reserved with some purpose in mind (IP masquerading?), but
regardless this restriction is being inappropriately applied to the class-D
multicast range.

Keywords: networking, kernel, multicast

Kernel version: 2.2.16-3 (and others)

Environment (example):
Kernel modules 2.3.10-pre1
Gnu C egcs-2.91.66
Linux C Library
Linux C++ Library
Procps 2.0.6
Mount 2.10f
Net-tools (1999-04-20)
Kbd [option...]
Sh-utils 2.0
Sh-utils Parker.
Sh-utils Inc.
Sh-utils NO
Sh-utils PURPOSE.

Example trigger of problem: use any classic multicast app to join a session
that utilizes a port in the restricted range.

Other notes, patches, fixes, workarounds: No external solution is available,
since sessions are announced using automated tools (SDR) on various OSes,
and it's unreasonable to force users to recompile and run a hacked kernel to
use multicast or run programs such as vic/vat as setuid root (assuming
there's a way for root to get around this restriction, which I'm not sure is

I've already mentioned this problem in other forums (both physical and
electronic), and basically received no informed responses.



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