Whether you're using BitTorrent's web UI, forwarding ports for gaming, or streaming media to your phone, you sometimes need to know the IP addresses of your computers. The problem is, if you use DHCP (as most people do), those computers get re-assigned IP addresses every time you reboot them - which means you have to check what it is every time. You can avoid this hassle, however, with something called DHCP Reservations, which let you reserve specific IPs for each computer on your network. That way, they'll always have the same IP address and you never need to worry about checking it again.
Note: If you've heard of static IP addresses before, this is very similar. Since you manage it all from the router, though, it's a bit easier to set up. If, for some reason, you can't use DHCP reservations, you can set up a static IP on each of your computers instead, but this is our preferred method.
Many routers support DHCP reservations out of the box, but if they don't, you can always install the DD-WRT firmware, which adds the support to many more routers. Every router is a bit different, but in general, here's how to set it up:
- Head to your router's configuration tool by typing in your router's IP address in your browser's navigation bar. Usually this is something like
192.168.0.1. You can check it by running
ipconfigin a Command Prompt, or heading to System Preferences > Network on a Mac.
- Find the DHCP reservation setting. This could also be called "DHCP Static Lease" or something similar. On my router, it was under the "Gateway" category.
- Head to the computer for which you want to reserve an IP address and find its MAC address. Once again, you can find this by typing
ipconfiginto a Windows Command Prompt, or by going to System Preferences > Network on a Mac, clicking on your Wi-Fi card or Ethernet port, hitting Advanced, and going to the Ethernet tab. Your MAC address will be in the form 00:00:00:00:00:00. Note that a Wi-Fi card and Ethernet port will have two different MAC addresses, and you can't assign them both to the same IP, so pick the one you use primarily.
- Type that computer's MAC address into the first entry in the DHCP Reservation setting. Then, type in the IP address that you want to reserve for that machine. Hit Apply, or whatever button is available to you.
- Repeat with any other computers that you want to reserve
ipconfig /renew and then
ipconfig /release in a Windows Command Prompt, or by going to System Preferences > Network on a Mac, turning your Ethernet or Wi-Fi card off, and then back on again. If you then check your IP address (either with ipconfig on Windows or by checking the Network Preference Pane on your Mac), you should see that they have their new reserved IPs, which they'll use every time you turn them on.