Bug 10689 - Multicast doesn't work unless promisc or allmulti is on
Multicast doesn't work unless promisc or allmulti is on
Product: Red Hat Linux
Classification: Retired
Component: kernel (Show other bugs)
All Linux
medium Severity medium
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Assigned To: Alan Cox
Depends On:
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Reported: 2000-04-10 00:15 EDT by matt.domencic
Modified: 2008-05-01 11:37 EDT (History)
0 users

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2000-08-08 16:48:55 EDT
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Description matt.domencic 2000-04-10 00:15:15 EDT
I'm using 6.0 and a Xircom PCMCIA ethernet card (xirc2ps_cs).

MULTICAST is enabled (so says ifconfig)

However, I can't receive multicast packets unless the interface is switched
to PROMISC or ALLMULTI.  I do see that the multicast group was joined (via
/proc/net/igmp), but no packets arrive.
Comment 1 Anonymous 2000-04-10 17:49:59 EDT
As it turns out this may not be a bug - it is definitely a behavior difference
between the 2.0.x and 2.2.x kernel though.  In 2.0.x you are permitted to create
a socket, join a group, and then bind the socket to the multicast address you
are interested in.  In 2.2.x, you must bind first, and then join the group.
Comment 2 Anonymous 2000-04-10 19:03:59 EDT
Argh.  Scratch that.  It still will not work under 2.2.x, but works beautifully
in all possible ways under 2.0.x.

I have now verified this behavior with several ethernet cards using different
Comment 3 Anonymous 2000-04-27 17:51:59 EDT
I've tracked down the problem further.  It only happens with a PCMCIA ethernet
card.  A regular ethernet card works fine.  The behavior happens with both
pcmcia-cs 3.1.10 and 3.1.14
Comment 4 Jeff Johnson 2000-05-15 06:26:59 EDT
This is a kernel problem. Changing component.
Comment 5 Alan Cox 2000-08-08 16:48:35 EDT
Does this still occur with 3.1.18
Comment 6 Alan Cox 2000-08-08 16:48:53 EDT
Does this still occur with 3.1.18

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