jail.conf ignoring exec.fib?

Arthur Chance freebsd at qeng-ho.org
Wed Aug 21 11:35:24 UTC 2013

On 21/08/2013 11:35, Karl Pielorz wrote:
> --On 20 August 2013 18:02 +0100 Arthur Chance <freebsd at qeng-ho.org> wrote:
>> And that's just made me think of something else - I have a horrible
>> feeling that jexec will attach to the jail using whatever fib it's
>> running under, i.e. the fib from the host environment. Do you have (or
>> can you enable) ssh running in the jail? If so, log into the jail that
>> way, and see what
>>     sysctl net.my_fibnum
>> shows then, because you'll be running under the environment created by
>> /etc/rc.
> Ok, one word: Bingo. That was it. I'll spare you the gory details of how
> I cut myself off from the machine, managed to create a jail with no
> access etc. etc.
> But yes, that was it - in summary:
>   jail -c -v  Does not actually *show* the fib being set, but will show
> an error if the setfib call fails.
>   jexec       Runs a process in the jail, using the prevailing fib - not
> the jails fib, you can rectify this by using 'setfib X jexec jail tcsh'
> I don't know if that last point should be considered a 'bug' or not...

Certainly the jexec problem is going to bite people again and again, so 
you should probably file a PR for it. As for the -v option, the man page 
says "Print a message on every operation", so it's down to what is or 
isn't regarded as an operation worth reporting.

> Many thanks for your help!

No problem, it helps me understand jails better as well.

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