From owner-freebsd-questions@freebsd.org  Tue Jan 10 17:04:14 2017
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Date: Tue, 10 Jan 2017 09:04:06 -0800 (PST)
From: Robroy Gregg <robroy@robroygregg.com>
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To: Ernie Luzar <luzar722@gmail.com>
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Subject: Re: /dev/bpf in a jail
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Good day Ernie,

On Tue, 10 Jan 2017, Ernie Luzar wrote:

> I trying to run tcpdump inside of a jail.
> Get following error message
> tcpdump: (cannot open device) /dev/bpf: No such file or directory
>
> Is it technical possible to do this?

Yeah, I have tcpdump working in a jail on 10.3-RELEASE, named "beak."

Here's the jail.conf for it:

    exec.start = "/bin/sh /etc/rc";
    exec.stop  = "/bin/sh /etc/rc.shutdown";
    exec.clean;
    mount.devfs;

    host.hostname = $name;
    path = /j/$name;
    interface = igb0;

    beak {
        allow.raw_sockets;
        devfs_ruleset = 7;
        enforce_statfs = 1;
        ip4.addr = 192.168.32.10;
    }

And here's the /etc/devfs.conf for it:

    [devfsrules_jail_bpf=7]
    add include $devfsrules_hide_all
    add include $devfsrules_unhide_basic
    add include $devfsrules_unhide_login
    add path 'bpf*' unhide

Wellbeing to you, Ernie.

Robroy