[Dnsmasq-discuss] Can dnsmasq 'alias' a host name?

[Simon Kelley]

Chris G wrote:
> On Wed, Sep 02, 2009 at 08:46:01PM +0100, Simon Kelley wrote:
>> Chris G wrote:
>>> On Wed, Sep 02, 2009 at 05:51:15PM +0100, Simon Kelley wrote:
>>>> Chris G wrote:
>>>>> Can dnsmasq provide an alternative name for a client?
>>>>>
>>>>> This is going on from my problem with a system that insists on calling
>>>>> itself garage.local when I want it to be called garage.
>>>>>
>>>>> Is there a way that I can tell dnsmasq that garage.local is also
>>>>> garage so that requests for the address of garage will get the address
>>>>> of garage.local?
>>>>>
>>>> yes.
>>>>
>>>>
>>>> cname=garage,garage.local
>>>>
>>>> should do it.
>>>>
>>> It doesn't seem to work though.  I have added the following to the end
>>> of /etc/dnsmasq.conf :-
>>>
>>>     cname=garage,garage.local
>>>
>>> I have killed and restarted dnsmasq (it's still providing DNS OK).
>>>
>>> However I can't ping or ssh to garage, but I can ping and ssh to
>>> garage.local. 
>>>
>>>
>> The fact that this thing is putting .local on the end of its name
>> suggests that is might be doing mDNS, and that the host you are testing
>> it with is also configured to use mDNS as a name-resolution method.
>> Since dnsmasq doesn't have anything to do with mDNS, it can't affect that.
>>
>> Some things to check:
>>
>> 1) /var/lib/misc/dnsmasq.leases. Does the garage.local name appear
>> there, it will if the NAS is announcing that name in its DHCP requests.
>>
> /var/lib/misc/dnsmasq.leases contains:-
> 
>     1251924290 00:0b:5d:7f:56:e0 192.168.1.90 MAXLAPTOP 01:00:0b:5d:7f:56:e0
>     1251923804 00:01:e3:9d:8b:b5 192.168.1.129 C475IP *
>     1251923525 08:00:27:24:d0:9c 192.168.1.144 xp 01:08:00:27:24:d0:9c
>     1251922953 00:90:a9:70:06:ff 192.168.1.88 * 01:00:90:a9:70:06:ff
>     1251923251 00:e0:4c:c0:a9:60 192.168.1.89 lounge *
>     1251923827 00:50:8d:93:fd:09 192.168.1.83 maxine *
> 
> That 192.168.1.88 is the garage system.
> 
> 
>> 2) /etc/nsswitch.conf does mdns appear in the hosts: line?
>>
> Yes:-
> 
>     hosts:          files mdns4_minimal [NOTFOUND=return] dns mdns4
> 
> 
>> 3) Try "dig garage.local" which just does a DNS query and doesn't try
>> the other name-resolution methods.
>>
>     ; <<>> DiG 9.5.1-P2 <<>> garage.local
>     ;; global options:  printcmd
>     ;; Got answer:
>     ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 10135
>     ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
> 
>     ;; QUESTION SECTION:
>     ;garage.local.                  IN      A
> 
>     ;; Query time: 0 msec
>     ;; SERVER: 127.0.0.1#53(127.0.0.1)
>     ;; WHEN: Wed Sep  2 20:49:35 2009
>     ;; MSG SIZE  rcvd: 30
> 
>> There are ways around this, but we need to know exactly what's going on
>> first.
>>
> Thanks for all the help so far.  Yes, I think mDNS may be getting in
> the way.  Turning it off is fine, especially if I can just persuade
> the garage system to be 'normal'!  :-)
> 
> The garage system has the following running:-
>     3817 root       1024 S   /usr/bin/mDNSResponder -f /etc/mDNSResponder.conf 
>     3818 root       1024 S   /usr/bin/mDNSResponder -f /etc/mDNSResponder.conf 
>     3819 root       1024 S   /usr/bin/mDNSResponder -f /etc/mDNSResponder.conf 
> 

Yes, that name is coming from mDNS, and not from the NAS announcing its
name when it does DHCP.

You need to stop using mDNS for name resolution (edit
/etc/nsswitch.conf) and then, since the NAS doesn't tell dnsmasq its
name, you need to tell dnsmasq that the host with MAC address
00:90:a9:70:06:ff is "garage".


dhcp-host=00:90:a9:70:06:ff,garage

you can remove  the CNAME line too, it's not needed.


Cheers,

Simon.