The Address Resolution Protocol (ARP) is a key TCP/IP protocol that is used to determine the physical address of the network card that corresponds to an IP address. When you’re troubleshooting TCP/IP connectivity problems on a Windows network, you may need to investigate or modify the ARP cache as you look for problems.
Windows comes with a command-line utility called ARP, which you can use to display or adjust the contents of the ARP cache of either a local or remote system. To make the tool easier to use, I created the ARP Gadget, which automates the ARP command. Let’s take a closer look.
Using the ARP Gadget
The ARP Gadget runs from the Windows Sidebar in Vista and the Desktop in Windows 7 and presents each of the ARP command-line tool’s options on a flyout menu, as shown in Figure A. All you need to do is select the options you want to use and click the OK button. When you do, the ARP Gadget opens a Command Prompt window and runs the ARP command, along with the selected options. If you need more information about an option, you can hover your mouse pointer over it to display a tooltip. You can also select the ARP /? check box.
The ARP Gadget displays each of the ARP command-line tool’s options on a flyout menu.
Adding and deleting entries requires elevated privileges, so you’ll encounter a UAC when you perform either of those operations and click OK. Once you work through the UAC, the command will run.
When the ARP Gadget sends the selected command to the Command Prompt window, the command line won’t appear in the window. If you want to see the command line, select the Show Command Line check box before you click OK.
Once you download the arp_gadget_package.zip file, you’ll find that it contains two files:
- ARP Gadget Readme.pdf
Simply extract both files to a folder of your choice and rename the ARP.zip file to ARP.gadget. Make sure that you have Windows Explorer configured to display file extensions. (On the View tab of the Folder Options dialog box, deselect the Hide Extensions for Known File Types check box.) Otherwise, the system might still have the file type set as .Zip even though it appears that you have renamed the extension to .gadget.
To continue, follow the appropriate steps for your version of Windows.
- Right-click on the ARP.gadget file and select Windows Sidebar from the Open With submenu.
- In the Windows Sidebar – Security Warning dialog box, click Install. The ARP Gadget will be installed in the Windows Sidebar and will be ready to use.
These steps are illustrated in Figure B.
Click Install in the Windows Sidebar – Security Warning dialog box.
- Right-click on the ARP.gadget file and select the Open With command.
- In the Open With dialog box, select Windows Desktop Gadgets and click OK.
- In the Desktop Gadgets – Security Warning dialog box, click Install. The ARP Gadget will be installed in the Desktop and will be ready to use.
These steps are illustrated in Figure C.