Since it won't be possible to do it as a normal user without special settings. (A normal user should not be able to break the system by default...) If you can convince the administrator that you need to do it, they can add the relevant command for your user to the sudoers file... (Looks like you basically want the DHCP client to restart). Seems like you'll need access to the
ipconfig command. (
sudo ipconfig set en0 NONE; sudo ipconfig set en0 DHCP (replace en0 with your ethernet interface as reported by
ifconfig) should do it...)
You might also want to check if there is a group that you can be added to to allow you to access network settings...
Looks like another method is to set up multiple network "Locations" (admin will need to do it) and you can then switch between them using
scselect, seemingly without admin rights...
The administrator should be able to limit you to only those commands in su.
(Some of this info comes from a superuser post I found (but can only access via Google cache where I am currently..))