devfs and bpf owner, group, and mode

David Kelly dkelly at
Tue Nov 8 15:08:20 GMT 2005

I'm having problems in 5.4 getting automatic ownership and mode correct
on /dev/bpf2. Added this to /etc/devfs.conf:

# Allow group tcpdump to use bpf*
own     bpf0    root:tcpdump
perm    bpf0    0660
own     bpf1    root:tcpdump
perm    bpf1    0660
own     bpf2    root:tcpdump
perm    bpf2    0660

And this to /etc/devfs.rules:

add path 'bpf*' mode 0660 group tcpdump

The intent is to allow members of group "tcpdump" to use /dev/bpf2
without being root. The above creates /dev/bpf[012] as desired at boot
but some time later /dev/bpf2 disappears.

System has two NICs, xl0 and fxp0. At this time fxp0 is not being used.
Vlan0 is configured (as a VLAN of course) on xl0, and thats where I need
/dev/bpf2 for tcpdump to see what my stuff is doing.

If missing, /dev/bpf2 is created automatically when tcpdump opens, but
its not created with the same ownership and mode as during reboot.

Suspect my problem is related to [devfsrules_bpf=5] or the fact I
haven't informed the system to apply this rule to the /dev filesystem.

So where is the 'i' that I've failed to dot?

David Kelly N4HHE, dkelly at
Whom computers would destroy, they must first drive mad.

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