Changing Tcp/ip Dhcp From Manual To Automatic On A Mac

This trick has been around in Mac OS X for quite some time, but it often doesn’t get the attention it deserves. I use this constantly for changing network needs, and have configurations setup for auto and manual DHCP, proxies, alternate DNS settings that are faster on some networks, and a variety of other networks.

Changing Tcp/ip Dhcp From Manual To Automatic On A Mac Pdf
Change From Manual To Automatic
Changing Tcp/ip Dhcp From Manual To Automatic On A Mac Pro
Changing Tcp/ip Dhcp From Manual To Automatic On A Mac Drive

Dynamic Host Configuration Protocol, or DHCP for short, is a protocol that enables your MacBook to retrieve all the networking information you need. Before you can use DHCP, you have to add a DHCP server, which provides other computers on the network with their configuration settings.

Learn how to manually configure the TCP/IP address within Windows 7. Dynamic Host Configuration Protocol - Duration. Changing your Dynamic IP address to a Static address in Windows 7.
Aug 21, 2012 MacRumors Forums. Forums Macs Mac Basics and Help. Is it possible for a Mac using DHCP to have a static IP? Changing it to 'Using DHCP with manual address' and entering a 192.168.x.x address resolved the issue. I'm certainly no expert when it comes to networking, so I don't fully understand why this worked, but it did.

Most Internet connection-sharing hardware devices (and software-sharing implementations as well) provide a DHCP server as part of the price of admission. (Internet connection sharing allows all your networked computers to access the Internet through a single Internet connection.) Most wired and wireless routers can provide DHCP services these days. Technology marches on.

If you plan to use Internet connection sharing or you know that you have a DHCP server on your network, you can set up your MacBook to automatically obtain the required IP address and information. Open System Preferences from the Dock or the Apple menu and choose Network.

From the Network dialog that appears, click the Ethernet entry in the list on the left. Choose Using DHCP from the Configure IPv4 pop-up menu; then click the Apply button. Mac OS X contacts the DHCP server to obtain an IP address, a subnet mask, a gateway router IP address, and a Domain Name System (DNS) address. (DNS servers convert a human-friendly address to a computer-friendly IP address, like 66.218.71.86.)

A few seconds after clicking the Apply button, you should see the information come up, as provided by the DHCP server. This lets you know that the process worked and configuration is complete. You might also notice that the DNS Servers information is empty (or grayed out).

Fear not: Mac OS X is really using DNS information provided by the DHCP server. Press Command+Q to quit System Preferences and save your settings.

If you ever make a network change that screws things up, such as entering the wrong subnet mask or an IP address that isn’t in the same range as others on your LAN, you can always click the Revert button to get back your old settings.

One DHCP server on a network is princely, but two or more DHCP servers on a single network will fight like alley cats and grind everything to a halt. Therefore, if you’re considering adding a DHCP server to an existing network, make doggonesure that you’re not treading on another server’s toes. (Ask that network administrator person.)

DHCP makes it simple to configure network access for your home network, and port forwarding makes it easy to those computers from anywhere. By configuring static DHCP on your router, you can combine the best of both worlds.

The Problem with DHCP and Port Forwarding

DHCP is great. You configure your router to automatically assign IP addresses and the computers on your network just plain work. Port forwarding is useful because you can access your router from outside of your network and be redirected to the computer you need inside of your network. The problem is that these two wonderful things rely on one premise: your internal IP addresses don’t change. If your router changes the IP that is assigned to a machine by DHCP, then you have to reconfigure Port Forwarding. Many programs try to get around this fact by offering Universal Plug and Play (UPnP) port forwarding features, but not everything does.

Newer routers often have the ability to remember which IP address was assigned to which computer, so if they disconnect and reconnect their IP doesn’t change. Often, though, a router reset will wipe this cache and start assigning IPs on a first-come, first-served basis. Tons of older routers don’t even have this ability, and immediately assign new IP addresses. With IP addresses changing, you have to reconfigure your port forwarding settings often, otherwise you may lose the ability to connect to your home computers.

You can do this on plenty of modern routers, but we’re going to use DD-WRT for this guide. We’ve touted DD-WRT’s ability many times before, and it’s not for nothing. This amazing custom router firmware has a solution to this mess: static DHCP, also known as DHCP reservation. While configuring your router for DHCP, you have the ability to enter the MAC addresses of your computers’ network cards and enter which IP address to assign them. DD-WRT will automatically take care of the rest! If you have a different router, you can try following along using your router’s own admin page–the instructions should be somewhat similar.

Finding Your MAC Address

The only real work you’ll have to do is find the MAC address of each computer’s attached networking card. If you’re using wireless then you should find the MAC of your wireless card, and if you’re wired then use the Ethernet card.

Just go down to the icon in your system tray for your connection and click it. Mine is wireless.

Right-click on your current active connection and click on Status.

Changing Tcp/ip Dhcp From Manual To Automatic On A Mac Pdf

Click on the “Details…” button.

Your MAC address for this device is listed as “Physical Address.”

OS X users can check under their System Settings and click on Network. If you click on the various tabs for your connection, you should find a “Physical ID,” “Ethernet ID,” or “MAC Address.” Ubuntu users can type “ifconfig” in Terminal. You’ll see various network adapters, each displaying its own hardware address. Do this for all of the computers in your network that you need port forwarding for. The others will just get their IPs assigned automatically by DHCP.

DD-WRT and Static DHCP

Change From Manual To Automatic

Now that you have a list of MAC addresses for each of your computers, open up a browser tab and head over to your router’s DD-WRT interface. Click on Setup, and under Basic Setup, make sure DHCP is turned on.

Scroll down to “Network Address Server Settings (DHCP)” and make a note of the starting IP address and the maximum number of users. The addresses you configure should fall within this range. Here, my range of IPs would be 192.168.1.100 – 192.168.1.114.

Now, click on the Services tab up top.

Changing Tcp/ip Dhcp From Manual To Automatic On A Mac Pro

Under the DHCP Server section, you can see that there’s a list of “Static Leases” click on the Add button to add a new one.

Enter the MAC address of each computer, give each one a name so you know which is which, and then assign them an IP address. You won’t be able to add the same IP address to two different MAC address, so make sure each MAC has a unique IP. If your version of DD-WRT also has a space to enter the “Client Lease Time,” a safe setting would 24 hours, or 1440 minutes.

That’s it! Be sure to click on both the Save button and the Apply Settings button, and wait for the changes to take effect. The settings should automatically change when each computer’s lease expires, though you can reconnect from each computer if you want the changes to take effect immediately.

Changing Tcp/ip Dhcp From Manual To Automatic On A Mac Drive

Now, whether your computer loses its connect, the router gets power cycled, or the DHCP lease expires, each computer you entered into the list will stick to its assigned IP. Furthermore, you won’t have to manually configure static IPs on each machine! Port forwarding won’t have to be a pain ever again.

Does your router support DHCP reservations? Do you have a more clever use for this system? Share your thoughts in the comments!