How to generate a packet filter device driver in Ultrix

[Jeffrey Mogul]

In article <28528.27b72f38 at kuhub.cc.ukans.edu> jian at kuhub.cc.ukans.edu writes:
>I want to config one of ethernet interfaces on the DEC 3100 running Ultrix 
>4.1 to be in a promiscous mode. Does anyone have experience with this matter?
>
>I got some hints from the menu that I need to create a psudo packet filter
>device driver first. The command for creating the packet filter device is:
>
>               #MAKEDEV pfilt
>
>I followed what the menu says. But I could not open the packet filter device
>after I created it. I saw there are some pfiltnnn files in the /dev/pf/
>directory. Am I missing something. I would appreciate any helps.

You should first of all make sure that your kernel has been built
with the proper options: see "man packetfilter(4)".  I believe that
the default configuration does not include the packetfilter.

I'm not quite sure how you intend to use the promiscuous mode support
of the packet filter, but quite often people neglect to run
	/etc/pfconfig +p <interface-name>
which is necessary before using a promiscuous-mode application.  I
put this in my /etc/rc.local; it has absolutely no effect unless a
promiscuous-mode application is running.  See the manual page.

If you want an example of how to write an application, you can
obtain the sources for tcpdump or nfswatch from gatekeeper.dec.com
via anonymous FTP:
	pub/net/tcpdump-2.0.tar.Z
	pub/net/nfs/nfswatch3.0.tar.Z

-Jeff