DHCP gives an IP when the DHCP relay is not in the subnet

[perl-list]

Without the bit about not giving an IP (or an IP from a different subnet) if the relay is 10.1.1.4, you could do it something like this: 

shared-network SomeNetwork { 
subnet 192.168.1.0 netmask 255.255.255.0 { 
option routers 192.168.1.1; 
option subnet-mask 255.255.255.0; 
pool { 
range 192.168.1.2 192.168.1.254; 
} 
} 
subnet 10.1.1.0 netmask 255.255.255.0 { 
} 
} 

which alerts the DHCP server that requests from 10.1.1.0/24 are in the same physical network as 192.168.1.0/24 and so it will pick a pool address from 192.168.1.2 - 192.168.1.254 

as for how to not answer when 10.1.1.4 relays (or answer with a different subnet's IP), that is beyond my knowledge. 

> From: "Mik J" <mikydevel at yahoo.fr>
> To: dhcp-users at lists.isc.org
> Sent: Thursday, January 5, 2017 12:36:58 PM
> Subject: DHCP gives an IP when the DHCP relay is not in the subnet

> Hello,

> Is it possible that the dhcp offers an IP but the dhcp relay is not in the
> subnet ?

> I have a vlan 192.168.1.0/24 and 3 dhcp relay. Each dhcp relay will use a
> loopback to relay the dhcp request 10.1.1.1 or 10.1.1.2 or 10.1.1.3. The client
> machines will receive an IP in 192.168.1.0/24

> Is it possible ?

> NB: if there's a DHCP relay in 10.1.1.4, I don't want to offer an IP in
> 192.168.1.0/24

> Do you have a link or keywords that would help to find the typical configuration
> for that

> Thank you

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> dhcp-users mailing list
> dhcp-users at lists.isc.org
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