How to Apply the ARP-Fix for Colocated Macs
"Why do I have constant issues connecting to my colocated Mac running OS X?"
This question doesn't come up often, but it’s worth sharing the most likely answer and how to fix the issue permanently.
If you’ve been with MacStadium for a while or have ever used a Mac behind multiple network gateways in the past, you are likely aware of the networking issue present in previous versions of Apple’s OS X operating system.
The simple issue is that OS X 10.9 and OS X 10.10 included a feature that was incompatible with certain network configurations apparent in most data center and corporate environments. Mac servers running either OS version were having difficulties maintaining a network connection and required constant reboots. We researched the issue and got in touch with both Apple and Cisco, a networking technology company that develops software we use in part of our network. Here’s our post explaining the issue if you want to learn more.
What does that mean for you, today?
If you only subscribe to servers from MacStadium you have nothing to worry about. We apply this fix to all of our Mac computers as part of our deployment process. It’s completely automated and we’ve done it with thousands of servers in the past year and will continue to do so with installs of OS X 10.9 and 10.10 into the foreseeable future.
On the other hand, if you’re a current or prospective colocation customer (send your Mac) then your Mac may be susceptible to this issue if it’s running OS X 10.9 or 10.10. Making sure your personal machine is online at all times is a priority for us.
We’ve created a simple tool in our account dashboard for you to detect whether the fix is enabled, enable it, or disable it. See below for the steps.
How to Enable the ARP-Fix from the Account Dashboard
Step 1: Log into your account dashboard.
Step 2: Select one of the colocated Macs that you would like to check the ARP fix status of, or if you would like to enable or disable the ARP fix on.
Step 3: Click on the "ARP Fix" tab for the selected Mac.
From here you can check if the ARP fix has yet been applied to the colocated Mac, or enable and disable it.
Step 4: Verify the IP address of the Mac you would like to detect the ARP status for and input your username and password.
This will allow us to check whether the ARP fix is enabled or needs to be installed.
Step 5: Click Check Status.
You’ll receive a response with the current OS X version and the ARP-Fix status. If you receive an error, verify that the computer with the chosen IP address is online and that your username and password are correct then try detecting status again.
If the status is Enabled, you’ve got nothing else to worry about. Please open a support ticket if you are still having network connectivity issues.
If the status is Disabled, please click the Enable button to apply the ARP-Fix. After a few seconds you will receive a response that it was successful and that your server requires a reboot.
You can do a software reboot by logging into the Mac as you would normally through RDP, VNC, Screen Sharing, or SSH.
An alternative to that is to do it directly from the dashboard you're already looking at. Navigate to the Actions button on the right for the selected Mac and click Hard-Reboot in order to hard reboot the power outlet your server is plugged into. See below:
After waiting 30-60 seconds for your server to come back online fully, navigate back to the ARP-Fix page and detect ARP-Fix status once more. You’ll receive a status of Enabled and then you’re done.