Re: DHCP release
DHCLIENT is the tool. In a terminal run:
sudo dhclient -r
Here is the excerpt from the man page for dhclient
The client normally doesn’t release the current lease as it is not required by the DHCP protocol. Some cable ISPs require their clients to notify the server if they wish to release an assigned IP address. The -r flag explicitly releases the current lease, and once the lease has been released, the client exits.
My System: 9.04 - Dell Latitude D620, Video: Intel 945GM, Audio: Intel 82801G, Wireless: Intel 3945ABG, Ethernet: Broadcom CM5752, Bluetooth: Toshiba Internal