Convice Bind to listen on IP alias with a range of IPs.

[michoski]

On 5/1/12 2:32 PM, "Augie Schwer" <augie.schwer at gmail.com> wrote:
>> Contrary to what a lot of other people have suggested, it is in fact
>> possible using the socket API to bind() to IPs which aren't explicitly
>> created, due to special handling on the loopback interface. This can
>> certainly be done under Linux, for example., and I have just re-confirmed
>> that to myself.
> 
> Thank you for confirming for others that this is a real feature.

The feature wasn't argued, I even showed it working with 127/8, but rather
what BIND will listen-on...

>> Unfortunately, it seems likely that named is using the normal socket APIs to
>> first enumerate the list of IPs on the box, and then filter those through
>> listen-on statements to get the final list of IPs to pass to a bind() socket
>> call - this would be a sensible way to implement the CIDR listen
>> functionality.
>> If so, then if the IP isn't *explicitly* on an interface, it won't appear in
>> the final output set, regardless of the fact a bind() call will succeed.
> 
> OK, that makes sense, I have found that the following work-around does work:
> 
> sudo ifconfig lo:1 10.0.0.1 netmask 255.255.255.224
> sudo ifconfig lo:2 10.0.0.2 netmask 255.255.255.255
> 
> I get the full usable range on my loop-back interface, and Bind will
> happily now listen-on the 10.0.0.2 address.

Exactly what was answered by multiple people...  you need an alias with the
IP you want BIND to listen-on!

Alas, the English language is such that some times the same thing needs said
several different ways to be fully understood.

Glad you got it working.

-- 
For men use, if they have an evil turn, to write it in marble:
and whoso doth us a good turn we write it in dust.
        -- Sir Thomas More