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Old 09-11-2003, 09:02 PM   #1
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dhcp server and iptables firewall

Ive got a dhcp server on one network segment, 192.168.10.x, and my clients on another segment, 192.168.100.x . these are seperated by an iptables firewall on a multihomed machine. my problem is that when a machine on the .100 subnet sends a dhcp request to, i cant seem to make it forward to the 192.168.10.x segment. However, if i eventually get that far, will the dhcp server receive a proper arp reply for the client on another nic and network segment? should i be forwarding all arp between the two network segments? if so, how? i'd appreciate any help. right now im tying a firewall conf of:

iptables -t nat -I PREROUTING -i eth3 -p udp -s --sport 68 -d --dport 67 -j DNAT --to-destination

iptables -A INPUT -p udp --dport 67 -j ACCEPT

the dhcp machine accepts everything right now, it wont be locked down until i resolve this problem. thanks in advance for any help.

Old 09-12-2003, 08:45 AM   #2
Registered: Aug 2003
Distribution: Dead Rat
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You need to install a DHCP forwarder on the firewall node. Or fake one with IPtables.... Mandrake and Red Hat both come with one packaged, you just need to load and start it.

Or check out this website.
Old 09-12-2003, 09:52 AM   #3
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that looks like just what i need. thanks for the link and ill post results when i get them.

Old 09-15-2003, 06:35 PM   #4
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dhcrelay worked great. thanks for the help.



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