auto DHCP?

You are being much too brief. I don't understand what you mean by "getting a new IP" or "auto dhcp" mode. Did you configure (in the confconsole) eth0 to use DHCP rather than a StaticIP configuration?

Can you explain a bit more about your setup? How are you getting a new IP (e.g., What are you using for a DHCP server and how do you ask it to reassign a client's IP)

Usually DHCP is used in a regular client-server model. The clients broadcasts a DHCP request packet and the server responds by checking it's records and then telling the client what IP it can reside in. In other words, the client asks and the server responds.

That's how it usually works. I think what you might be asking about is support for the DHCP reconfigure extension (RFC3203) where the server can dynamically ask the client to renew it's IP configuration. Is that correct? If so we've never tested if that works with the DHCP client we're using (udhcpc), but it would be interesting to learn more about this, with your help.

Note that behind the scenes the confconsole doesn't actually configure the network directly, it just edits the configuration files in /etc/network and then asks the system's network configuration scripts to reconfigure your interface like this:

ifdown eth0
ifup eth0

Try to remove udhcpc and install another dhcp client instead:

apt-get update
apt-get remove udhcpc
apt-get install dhcp3-client

If that doesn't work, you might also want to try dhcpcd.

Yes eth0 is using DHCP but when i get a new IP i have to go back into confconsole and click on DHCP to get my new IP or it will stay on my old IP. Thanks.