[Dnsmasq-discuss] client name via DHCP

[Simon Kelley]

Helmut Hullen wrote:
> Hallo, Richard,
> 
> Du meintest am 10.02.11:
> 
>>>>> when I use the ISC DHCP, then I can see the name of the Windows
>>>>> client in "/var/state/dhcp/dhcp.leases".
>>>>>
>>>>> With dnsmasq as DNS and DHCP server I haven't found this feature -
>>>>> is it somewhere hidden?
> 
> [...]
> 
>> The hostname is in the dnsmasq.leases file.  Exact directory depends
>> on how you installed dnsmasq.  If you're using the leasefile-ro
>> option, then getting this information is dependent on your script
>> saving it somewhere.  If the client doesn't send a hostname, the
>> hostname column will have "*" or the mac address.
> 
> Sorry - there's a difference:
> 
> ISC DHCP shows
> 
> lease 192.168.0.60 {
>   starts 4 2011/02/10 08:13:27;
>   ends 4 2011/02/24 08:13:27;
>   cltt 4 2011/02/10 08:13:27;
>   binding state active;
>   next binding state free;
>   rewind binding state free;
>   hardware ethernet 74:f0:6d:00:7b:f5;
>   uid "\001t\360m\000{\365";
>   client-hostname "KB-PC";
> }
> 
> and "dnsmasq" shows
> 
> 1305130516 74:f0:6d:00:7b:f5 192.168.0.60 Client-A60 01:74:f0:6d:00:7b:f5
> 
> The client's own name is "KB-PC", dnsmasq reads "Client-A60" from a list  
> on the server (which is completely independent from the "real" client's  
> name).
> 
> I want to see the "real" client's name, it's a better help for guessing  
> who's the owner of the machine.
> 

So you want the hostname the client sends to the DHCP server, which is
not used by dnsmasq because it's overridden by on-the-server
configuration? That is available: it's set in the environment variable
DNSMASQ_SUPPLIED_HOSTNAME given to the lease-change script. (All the
environment variables are prefixed with DNSMASQ_, it really  is the
client's idea of the hostname, not dnsmasq's.

Writing a little script which logs this and the dnsmasq hostname, MAC
address, IP address or anything else useful should give you a file which
can be searched.

HTH

Simon.