I have a need to set up an on-demand dial-up PPP link on a machine which
currently is also running `mrouted' to route multicast packets
between two ethernet interfaces and an mbone tunnel.

The traffic through the PPP link is to be limited to TCP packets (just
telnet and ftp are needed), so I set up an IPF filter for that.
I thought that I might as well use those filter rules to keep
the ppp daemon from dialing on spurious multicast traffic.
But it didn't work. Even if I say `block {in,out} on ppp0 all'
IGMP traffic is still going out on the interface.

Is this a know feature??


I then turned to the the PPP daemon's `active_filter_out' option
but that does not seem to work _at all_..   No matter what filter
expression I use, no packets are ever discriminated by it, i.e.
either all packets rejected or all are accepted.

-pk