[Dnsmasq-discuss] Question to dhcp-lease-format in conjunction with dhcp-script

[Simon Kelley]

Michael Rack wrote:
> Hi,
> 
> i have a question to the dnsmasq dhcp-lease-format in conjunction with 
> dhcp-script. I have some devices with no hostname. When dnsmasq is 
> calling my dhcp-script with the init parameter, in what format have this 
> hosts to be exported?

Exactly the same format as the hosts file

<expiry time> <MAC address> <IP address> <hostname>|* <client-id>|*

> 
> Currently i create a output to stdout look like as follow:
>  > 1221753155 00:1f:3f:53:a2:38 81.95.xxx.117  01:00:1f:3f:53:a2:38
>  > 1221753001 00:17:31:83:0a:a2 81.95.xxx.119  01:00:17:31:83:0a:a2
>  > 1221753063 00:1d:73:18:18:ca 81.95.xxx.124  01:00:1d:73:18:18:ca
>  > 1221753205 00:04:0e:df:0f:dd 81.95.xxx.125 datapipe 01:00:04:0e:df:0f:dd
>  > 1221753257 00:1d:73:05:81:7c 81.95.xxx.22 AP001D7305817C 
> 01:00:1d:73:05:81:7c
>  > 1221753006 00:13:49:63:55:fd 81.95.xxx.25  01:00:13:49:63:55:fd
>  > 1221753059 00:16:01:f4:e8:59 81.95.xxx.41 buffalo-router 
> 01:00:16:01:f4:e8:59
>  > 1221753166 00:1f:3a:b5:bf:c3 81.95.xxx.87  01:00:1f:3a:b5:bf:c3
> Is this correct, or how to export this rows?

No, you need to have a * instead of the hostname when it's not present.
> 
> And other question:
> * What is the fifth part of the dhcp-lease-format?

Client-identifier.
> * Why is the MAC-Address prefixed with 01: ?
Because that's what many DHCP clients use as the client identifier (the 
01 means "ethernet") Not all do that though, so don't rely on it.

If you look in contrib/wrt/lease_update.sh in the dnsmasq tarball, it 
has exactly the right shell code to turn the arguments to the 
lease-change script into the correct format.

 >Why does dnsmasq forget to send the leading 00: ?
I've not seen that before, are you sure it's not a problem with your 
script, maybe you are mangling the lease database somehow: "old" events 
are generated for existing leases that will have been through your code 
and fed back to dnsmasq with an "init" call.

Cheers,

Simon.

> 
> Thanks,
> Michael.
> 
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