How do I change my IP address when I log in?
how do I change my IP address when I connect to the internet?
imac, Mac OS X (10.6.5)
Generally, you do not, your IP address is assigned by your Internet service provider.
Unless you have paid your ISP to have a fixed IP address at a Fixed location, such as a company web site. In that case you use system preferences -> network, IF AND ONLY IF your Mac is directly attached to the Internet. If you are behind a typical home router, then the router is where the IP address is configured.
Users do not get to pick their own IP addresses.