Linux - NetworkingThis forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.
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DHCP has a nice feature that I need in a program I'm coding (this post is related to some other posts I've made but has a new topic - DHCP)
I have problems with communicating between two hosts using completely different IP addresses (e.g [h1:192.168.0.5, eth0] <---> [eth0 h2:10.0.1.1 eth1 10.0.2.8]) but are sitting on the same link and should do so.
The thing is that the hosts drops the packets from the other host, this can be solved by adding this:
route add default dev eth0
but this messes up the packet routing to for h2, since it's default gw (e.g 10.0.2.1) will have conflicts with the new "default device". So this solution is not an option for me.
How DHCP solves this...(?)
Lets say h2 runs a DHCP server and h1 the DHCP client. This would cause no problems, h1 would send its discover to h2 and the process continous and h1 will finally get a new address say 10.0.1.6. (I have tried it so it works). When I did this I saw on Ethereal that the source address was 0.0.0.0 on the DHCP discovery packets arrive at the server!
-> Is this the trick (with src 0.0.0.0)?
-> Or how can the DHCP client get its packets to the DHCP server if it has a totaly different (current) IP address?
-> How is it possible to set the source address to 0.0.0.0 in a UDP packet?
Last edited by rickthemick; 10-29-2004 at 09:38 AM.
That's how dhcp discovery works. You ask a dhcp server for an IP address. You still don't have any address, so you use 0.0.0.0 source address (and broadcast destination address).
If the client and the server sit on the same layer2 subnet, they see each others' packets and they are able to communicate.