Problems Receiving UDP Broadcasts on Some Versions of Linux

From: Curt Sampson
Date: Mon Jan 25 2010 - 02:37:18 EST

I'm posting this here because it smells as if it may be something
a where a kernel network code developer might just say, "oh yeah,
obviously your problem is this."

I'm not subscribed to this list, so please cc me on any replies. (The
Mail-followup-to header may do this automatically for you.)

The short summary is that on two very similar servers on the same
network, an application that listens for broadcast UDP packets on a
given port works fine on the Ubuntu 8.04/Linux 2.6.24-26-server box but
does not receive the packets on the Ubuntu 9.04/Linux 2.6.28-17-server
box. I have confirmed that tcpdump sees identical packets being received
on both hosts.

Did something change between these two kernel revisions that I need to
listen differently?

Full details, including sample code, are available at:

Thanks for any help you can give me. Even if you're not sure, but have
clues I should consider following up, feel free to e-mail me. I'm
also happy to take pointers to kernel code I should read, if there's
enlightenment there.

Curt Sampson <cjs@xxxxxxxxx> +81 90 7737 2974
The power of accurate observation is commonly called cynicism
by those who have not got it. --George Bernard Shaw
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