Help: Tunneling multicast

From: Wayne Throop (throopw_at_sheol.org)
Date: 01/26/04 

Date: Mon, 26 Jan 2004 00:32:32 GMT

: "Bev A. Kupf" <bevakupf@myhome.net>
: I want to tunnel multicast DNS (zeroconf/rendezvous, multicast group
: 224.0.0.251, port 5353) between four subnets. The routers connecting
: these subnets do not route multicast, and I don't control the router.
: But I do have linux boxes in all four subnets. Is there a simple way
: for me to tunnel multicast between the subnets over unicast packets,
: making use of something like vtun or something that makes use of the
: Linux 2.4 tap/tun interface??

Dunno about that. But you should be able to run mrouted on the
linux boxen, which should do the trick. Not that I have extensive
experience with mrouted, but even though you don't have access
to THE routers, you can start up your OWN routing demons to
supplement them. On the other hand, mrouted isn't free,
and isn't trivial to use (though there's a linux howto on it).

Other possibilities are mtunnel and udptunnel. But these are more
intended to tunnel specific sessions in the rtp protocol. But they
might, or a trivial tweak to them might, do what you need with less
arcane incantations required th an mrouted. I've used tinkered versions
of udptunnel for this-n-that (but still rtp sessions, so nothing like
DNS). So these may or may not work. And be aware of the usual warnings
that apply to udptunnel, ie, tunneling a packet-orinted protocol over a
stream-orinted protocol can have unfortunate results, performance-wise.

( use google to find 'em )

Wayne Throop throopw@sheol.org http://sheol.org/throopw

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