Trying to get tcpdump to work

[Jeffrey Mogul]

In article <1991May7.141459.11191 at fcom.cc.utah.edu> cole at cc.utah.edu writes:
>I am trying to get tcpdump to work.  I have a ds3100 with Ultrix 4.1.  Here
>is what I did.
[summarized]
>made pfilt device (cd /dev; MAKEDEV pfilt)
>did pfconfig (/usr/etc/pfconfig +promisc)
>
>When I run tcpdump as root it says:
># tcpdump host 128.110.48.3
>ln0: No such device
>tcpdump: your system may not be properly configured; see "man packetfilter(4)"
>
>Also, if I do
># /usr/etc/pfconfig + promisc ln0 
>it reports no device ln0.
>
>Anybody see my mistake?  Thanks.

Almost certainly you have not reconfigured your kernel to include
the packet filter.  This is NOT included in the default configuration.
(Perhaps this default is a mistake, but at the time it seemed likely
that "most" Ultrix customers would not be using tcpdump, and would
rather have the extra free memory.  Here at WRL, all of our kernels
are configured to include the packet filter.)

As the message says, 'see "man packetfilter"' and 'man config', I guess.

-Jeff