[Dnsmasq-discuss] DHCP for pairs MAC:IP only

[john doe]

On 1/25/2018 6:57 PM, vip at iptrans.net wrote:
> 2018-01-25 18:42, john doe написав:
>> On 1/25/2018 4:55 PM, vip at iptrans.net wrote:
>>>
>>> Good day
>>>
>>> I have a DHCP-router based on dnsmasq with interface eth2 and 
>>> networks 192.168.100.1/24 192.168.102.1/24 10.0.0.1/27 on this 
>>> interface. There are computers-dhcp-clients on this network which 
>>> have to get IP based on their MAC-addresses. And if file 
>>> /etc/dnsmasq.conf doesn't contain line with corresponding MAC (option 
>>> dhcp-host) then this computer doesn't get an IP via my DHCP-router.
>>>
>>> But.
>>>
>>> In /etc/dnsmasq.conf:
>>>
>>> # Uncomment this to enable the integrated DHCP server, you need
>>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>> # to supply the range of addresses available for lease and optionally
>>> # a lease time. If you have more than one network, you will need to
>>> # repeat this for each network on which you want to supply DHCP
>>> # service.
>>> # dhcp-range=192.168.0.50,192.168.0.150,12h
>>>
>>> And if I uncomment "# dhcp-range" then I'll have computer-dhcp-client 
>>> which will get a ip address without corresponding MAC in 
>>> /etc/dnsmasq.conf.
>>>
>>
>> If I understand you correctly you want only hosts that have a matching
>> mac address to be given an address for a specific subnet
>> (192.168.100.0/24).
>> For that you can use the 'static' keyword:
>>
>> dhcp-range=192.168.100.2,static,12h
>>
>> In case it is not what you want dhcp-host should have the form:
>>
>> dhcp-range=192.168.100.2,192.168.100.253,12h
>> dhcp-host=ab:cd:ef:gh:ij:kl,fix-ip-to-be-given-to-host
> 
> Thanks.
> 
> :) My man page for dnsmasq doesn't have a information about optional 
> static mode for dhcp-range like on link 
> http://www.thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html:
> 
> "The optional <mode> keyword may be static which tells dnsmasq to enable 
> DHCP for the network specified, but not to dynamically allocate IP 
> addresses: only hosts which have static addresses given via dhcp-host or 
> from /etc/ethers will be served. A static-only subnet with address all 
> zeros may be used as a "catch-all" address to enable replies to all 
> Information-request packets on a subnet which is provided with stateless 
> DHCPv6, ie --dhcp-range=::,static"
> 
> For example configuration:
> 
> interface=eth2
> dhcp-range=192.168.100.0,static
> dhcp-range=192.168.102.0,static
> dhcp-range=10.0.0.0,static
> dhcp-host=ab:cd:ef:gh:ij:kl,192.168.102.10
> 
> With this configuration pc with mac "ab:cd:ef:gh:ij:kl" get 
> 192.168.102.10 and no other ip.
> Аnd any other pc with a different mac will not receive any ip from my 
> dhcp-server.
> 

If you want "fix" address and "non-fix" address on the same subnet 
(192.168.100.0/24):


dhcp-range=192.168.100.100,192.168.100.150,12h
dhcp-host=ab:cd:ef:gh:ij:kl,192.168.100.90

The above line means that the host with the mac address 
'ab:cd:ef:gh:ij:kl' will always get 192.168.100.90.
Any other hosts will get an ip addres from 192.168.100.100 to 
192.168.100.150 (50 addresses available).

Normally you would use one subnet per interface:

interface=eth2
interface=eth3
dhcp-range=192.168.100.100,192.168.100.150,12h
dhcp-range=192.168.101.100,192.168.101.150,12h

The subnet to be used is the one set on the interface.

-- 
John Doe