i have the following configuration:

[ISP gateway/dhcp server] <==(adsl)===> [my linux router] <==(private lan)==> [other machines, some servers, some desktops]

the linux router routes traffic from the private lan to the internet and back.
now i'd like the machines in the lan to have public ip's, which are supplied by the isp's dhcp server. this way i could drop NAT:ing traffic and have all machines "directly" connected to the internet.

the router's ip address is also dhcp configured.

but i can't get dhcrelay to work.

tcpdump port bootpc and port bootps

on both interfaces has shown me that the router receives an dhcp request from a windows machine on the lan, and transmits it to the isp's dhcp server. however i never see a reply from the isp's dhcp server to the router.
could this be because the incoming dhcp request looks like

ip addresses src: 0.0.0.0 dst: 255.255.255.255

and the relayd dhcp request looks like:

ip addresses src: router_public_ip destination: isp_gateway_ip_address

and the isp's dhcp server is dropping the request because of this?
can anyone think of another reason why it doesn't work ?

thanks

//deice
// an intermediate linux network administrator

Are you sure your ISP provides you with public IPs for your LAN machines ? Otherwise (which is usually the case, considering the cost of fixed IP ranges), its dhcp server simply is not allowed to issue another IP to your router.

>Are you sure your ISP provides you with public IPs for your LAN machines ? Otherwise (which is usually the case, considering the cost of fixed
>IP ranges), its dhcp server simply is not allowed to issue another IP to your router.

i am quite sure, first, because the contract clearly states i have 5 public ip addresses via dhcp.
and second, because i had this system running with bridging, and that worked perfectly. all the machines were getting public ips via the linux bridge from the isp's dhcp server and everything worked quite fine.

but i want to switch to a routing setup so i can use all traffic shaping and other advanced features, and to isolate some machines from the internet with NAT and permit others full access. and simply as a learning exercise

//deice
// an intermediate linux network administrator