Hi, Al usual I hope this is not a faq, however majordomo didn't give me
a poiter to an archive of this list.
I've put a linux box with kernel 2.2.14 between a net and a cisco
router. It acts as a firewall, but firewalling and ipchains are not a
problem since I made my tests also without filters.
One of the users of the protected net uses multicast. It sends multicast
packets as usual, but they can't go through the linux box: they are
accepted on one interface but don't appear on the other. I don't want to
handle the packets, I just want to pass them to the original router. man
route() says:
> route add 224.0.0.0 netmask 240.0.0.0 dev eth0
> This is an obscure one documented so people know
> how to do it. This sets all of the class D (multi<AD>
> cast) IP routes to go via "eth0". This is the cor<AD>
> rect normal configuration line with a multicasting
> kernel.
It misses the -net, I suppose. Also in the kernel, in
/usr/src/linux/net/ipv4/route.c:
> } else if (res.type == RTN_MULTICAST) {
> flags |= RTCF_MULTICAST|RTCF_LOCAL;
> if (!ip_check_mc(dev_out, daddr))
> flags &= ~RTCF_LOCAL;
> /* If multicast route do not exist use
> default one, but do not gateway in this case.
> Yes, it is hack.
> */
So it seems that adding a routing entry for 224.0.0.0/240.0.0.0 pointing
to my default gateway should do what I need... but it doesn't. What am I
missing? I'm obviously not willing to install multicast routing software
on a firewall ;)
TIA
ciao
- Claudio
--
Claudio Telmon
[EMAIL PROTECTED]
http://www.telmon.org
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