Proxying broadcasts?

Nejc Škoberne nejc at
Wed Aug 27 22:07:23 UTC 2008


I have a central FreeBSD 7.0 router running pf with SERVERS and USERS1 and USERS2 networks
attached to it.

I also have some Sybase SQL servers on SERVERS network, which use broadcasts to announce
themselves to the network. Before, when there were no separate segments, everything worked fine
of course.

My question: is there any way to "proxy" (forward) broadcast requests from USERS1 to the
SERVERS network? So the users in USERS* networks could find Sybase SQL servers via broadcasts?

I tried something like this in my test environment (tried to NAT broadcasted DNS requests,
just for trying if pf could do it):

nat on $ServersInterface from to ->
rdr pass on $UsersInterface proto udp from to port 53 ->

(3.100 is a client from USERS1, 1.1 is the router)

But this doesn't seem to be working (no translated packets on the interfaces). I guess it's

I also analyzed traffic when Sybase client searches for servers - it sends one broadcast packet
(UDP) to port 2638 and servers reply directly to the client with UDP reponse packet.


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