pls help me

sonika_singhi · 03-09-2005, 06:09 AM

we are building dhcp server,
the problem is we are unable to detect DHCP-DECLINE AND DHCP-RELEASE
message types packets from the client.
what may b the problem.
we run the ethereal on the server to detect those packets, but the client is not sending these packets at the time of its shutdown.
We are able to detect DHCP-DISCOVER and DHCP-REQUEST packets from the same client but not DHCP-release from client and dhcp-decline from server.

pls help,
its urgent
thanx in advance

dylants · 03-10-2005, 03:21 AM

Perhaps the clients are not sending these messages. I believe that some clients do not do this, so as a dhcp server you have to leave the ipaddress allocated until the lease expires.

Have you got access to the clients? Can you install a packet sniffer on the clients?

Is it possible to look for another lease request from a device with the same mac address and if you get one then delete the old lease?

HTH

Dylan

sonika_singhi · 03-13-2005, 11:44 PM

how the server comes to know that client is not in need of the ip-add further-if it is not sending DHCPrelease packet
how to know that?

yes, we do run ethereal at client side but unable to detect those packets.

what may b the reason that the client is not sending those dhcpreleases

pls elaborate any solution if u have
its urgent

dylants · 03-14-2005, 03:20 AM

As I recall that is just the way that their dhcp clients have been programmed! If they're not sending a dhcp release then (in my opinion) you have to assume that the lease is still in use until the lease expires.
Does the rfc for dhcp state anything about this issue?

If you are running ethereal on the client and you can see the dhcp request and discover packets but not the release and decline packets then I would think that that is a very good indication that the client is not sending these responses.

Dylan

chrisfirestar · 04-13-2005, 03:07 AM

From my understanding DCHP Servers work this way for a reason. You set a release time of say 24 hours. (usually a longer period of time like 3 days) and that way you are not assigning a different IP address every day. It makes life easier for all involved I think.

Why you need to know when its released? whats the purpose of that?