how to do interval jail ips

Matthew Seaman m.seaman at
Mon Apr 6 15:25:31 UTC 2015

On 06/04/2015 15:53, Artem Kuchin wrote:
> 06.04.2015 17:46, Ernie Luzar пишет:
>> Artem Kuchin wrote:
>>> Hello!
>>> I have several jails and some of the use real ips, some are just
>>> internal for the server like 10.0.0.x
>>> However, i assigned all ips to the external em0 interface.
>>> This causes problems, because of server in the same lan have 10.0.0.x
>>> address of their interfaces too.
>>> So, there is a conflict.
>>> This is just a colocation, so, i cannot control the ip assignment.
>>> What is the correct way to assign ip address which are seen only
>>> withing a host?
>>> (some kind of virtual NIC)
>>> Artem
>> xl0,   for lan on device xl0
>> em0,x.x.x.x   for rl0 device facing pubic internet
>> use the correct device names for you network configuration
> i don't get it. I do not have xl0 device
> I only have em0
> Or i can specify whatever device i like even if it is not installed in
> the server?

You can create jail IPs bound to the loopback interface lo0 exactly as
you would for a standard NIC.

Be aware though that if you assign your internal IPs from, say, that will mean you would have trouble reaching anything on
that particular subnet via your network interface.  However as this will
be entirely internal to your machine, you could choose whatever IPs you
liked -- but preferably use ones from the RFC1918[*] defined ranges.



[*] Technically RFC6761 nowadays, but that covers a lot more than just
the reserved private address ranges.

Dr Matthew J Seaman MA, D.Phil.

JID: matthew at

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