Date: Thu, 19 Aug 1999 10:24:43 -0700 From: George Chung <gchung@microsoft.com> To: "'freebsd-net@freebsd.org'" <freebsd-net@freebsd.org> Subject: PLEASE HELP: mcast weirdness on private network Message-ID: <C35556591D34D111BB5600805F1961B910ECC116@RED-MSG-47>
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Hi Gurus: On a "normal" network (routers, connected to the inet), an app on NT4 and FreeBSD 3.2 can join an mcast group (225.0.0.1) and send/receive messages to each other on that address. However, when I move the binaries to a private network (no router) with NT4 and FreeBSD: An NT box is able to communicate bidrectionally with another NT box. The FreeBSD boxes are able to communicate bidrectionally with each other. The FreeBSD boxes are able to receive mcast packets from the NT boxes. BUT, the NT boxes aren't able to pick up mcast packets from FreeBSD!! Here's the network: m1 10.100.100.100 FreeBSD dual-homed (the 2nd interface is unconfigured). m2 10.100.100.102 FreeBSD dual-homed (the 2nd interface is unconfigured). m3 10.100.100.200 NT4 m4 10.100.100.202 W2K I had to tweak the FreeBSD boxes to get them to even work by adding a route for 225.0.0.1 (otherwise, I got a EHOSTUNREACH error when pinging 225.0.0.1). I am not sure I did this correctly. Here's my command: route add -net 225.0.0.1 -netmask 0xf0000000 -interface 10.100.100.100 The mcast code on FreeBSD does the following above and beyond the default (because they are multihomed): in the call to join the group, I specify the specific interface to receive on. I also call setsockopt to set the outgoing interface on mcast sends. I am scratching my head. The only thing I can think of is that Windows NT is filtering out IP packets whose source IP address it doesn't "know". But the only way I know how to do that for UDP sockets is to explicitly connect it to an endpoint. Any help would be greatly appreciated. Thanks, George To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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