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Date: Sun, 17 Mar 1996 09:19:57 -0800 (PST)
From: Robert Du Gaue <rdugaue@calweb.com>
To: Donald Burr <d_burr@ix.netcom.com>
cc: FreeBSD Questions <freebsd-questions@freebsd.org>
Subject: Re: How to use the 'snp' devices?
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> I compiled in the 'snp' pseudo-device into my kernel, which supposedly 
> allows you to 'snoop' on any Tty/Vty/Pty in your system.  I'd like to use 
> this for when I'm in X windows, so I can monitor the status of some 
> programs still running in text-mode VC's without having to switch out of 
> X.  How can I do this?  I know I use the "tcpdump" program to use the bpf 
> pseudo-device, is there a similar command to use the snp devices?

I assume you used : 

  pseudo-device   snp     2

Where here we're defining two snp devices..

> 
> Also, how do I make the devices in the /dev directory for snp devices?  
> MAKEDEV does not seem to have any commands to make them...

And then:

bash# ls sn*
snp0    snp1
bash# ./MAKEDEV snp2
bash# ls snp*
snp0    snp1    snp2
bash#


Worked fine here, though  you're right, it's not too well define in
./MAKEDEV (someone should probably put a comment in there...) :-) Here
is the section that creates it though in case yours is missing it for 
some reason:

snp?)
        unit=`expr $i : 'snp\(.*\)'`
        rm -f snp$unit
        mknod snp$unit c 53 $unit
        chown root.wheel snp$unit
        ;;