FreeBSD jails, dns and ping

[Matthew Seaman]

On 06/02/2018 16:17, James B. Byrne via freebsd-questions wrote:
> Note that local_unbound worked with both resolv.conf settings.  But
> both ping and pkg gave me grief with the first and worked with the
> second.
> 
> My understanding, admittedly perfunctory, has been that one is
> SUPPOSED to use 127.0.0.1 inside a jail wherever the standard loopback
> address is required. And that the jail system takes care of remapping
> 127.0.0.1 to whatever address is assigned to the loopback interface
> that the jail is configured to use.
> 
> What have I misunderstood?  Had I misconfigured something that is
> documented otherwise than what I had done?

Yes, that is the way it is supposed to work: any attempt to access 
127.0.0.1 (possibly 127.0.0.0/8 BICBW) or ::1 is remapped to the jail 
address.  Mostly this works fine, but some applications -- unbound(8) 
being one of them -- will detect that the packet was sent to 127.0.0.1 
but received on a different interface and drop the packet.

Your possible solutions are:

    * Tweak the local_unbound or unbound configuration to use the jail 
address explicitly.

    * Investigate VIMAGE jails, which have their own network stacks and 
consequently a lo0 interface within the jail.

	Cheers,

	Matthew