I have an isc dhcp server that is running on a server with three network segments. The primary network has an IP address. The other two do not. Can I configure the dhcp server to listen on and dole out IPs on the two networks that do not have assigned IPs? The idea being that there would be virtually no chance for traffic to bridge the primary onto the secondaries. It seems that without IPs on the secondaries, dhcp doesn't know how to map 'subnet' paragraphs with actual interfaces.
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4I don't know. Have you considered just trying it? It could take a whole 2 seconds. – Ryan Babchishin Sep 15 '16 at 21:56
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I did try it. Should have posted the message: – jmccanta Sep 15 '16 at 22:00
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No subnet declaration for eth0 (172.20.49.213). ** Ignoring requests on eth0. If this is not what you want, please write a subnet declaration in your dhcpd.conf file for the network segment to which interface eth0 is attached. ** – jmccanta Sep 15 '16 at 22:01
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4Did you try that too? – Ryan Babchishin Sep 15 '16 at 22:47
2 Answers
You cant, it break the rfc.
The dhcp server answer dhcp discover request, thus to answer, you need an ip, right? :) The first stage of the discovery is broadcast, but after no.
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No, you need IPs on the networks, or you won't be able to even define a subnet and range - which is the primary point of DHCP anyways. Not to mention it won't work past the first stage (broadcast from clients).
You're concerned with linking these networks together via the DHCP server - don't. You don't have to use it as a router. Just because it's on multiple networks does not make it a router. A router is wholly different than a DHCP server.
If you're concerned with having the ability to get to these other networks by SSH or something, lock that down (or don't install it on the DHCP box).
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