Middlebury

Network Troubleshooting - Mac OS X


= >> Information that we must have in a ticket <<=
  • Name and location (building, room #). Make sure we have their extension or cell #.
  • Jack ID (it’s on a silver or white tag around or ON the jack, e.g. "A-0-12").
  • 'IP address, MAC address and the result of running the "arp -a" command.


Typical troubleshooting steps

Typical troubleshooting steps on Macs include three main approaches:

  • Renewing the IP address
  • Turning the network card off and on again
  • Creating a new location, getting the IP, MAC address and running “arp -a".

IMPORTANT:

Release and renew DHCP lease (renew IP address)

  1. Click on the Apple logo (top left corner), click System Preferences. In the window that appears click Network.
  2. For Tiger: Click on the menu next to “Show” and select “Built-in Ethernet”. For Leopard, Snow Leopard, Lion, and Yosemite: Click on “Ethernet” in the list on the left, then click the button “Advanced” in the lower right corner.
  3. Under the “TCP/IP” tab click the button “Renew DHCP Lease”. Click the button “Apply” (located in lower right corner).
  4. Try opening the midd homepage now. Didn't help? See the section below.

Create a new location

  1. Open System Preferences => Network.
  2. Click on the menu next to “Location”.
  3. For Tiger: Select “New Location”. For Leopard, Lion, and Yosemite: Select “Edit Locations”, then click on the plus “+” button.
  4. Type in any name for the new location (e.g. Middlebury), click OK or Done. Click the button “Apply” (located in lower right corner).
  5. Creating a new location changes all network settings to their defaults (automatically obtain an IP, no proxy servers, no manual DNS servers, etc.). It also saves the customer’s custom settings.
  6. Try opening the midd homepage now. Didn't help? See section below.

Disable and re-enable the Network Card (NIC)

For Tiger:

  1. Open System Preferences => Network.
  2. Click on the menu next to “Show” and select “Network Port Configurations”. In the list of ports:
  3. To disable the NIC, remove the checkmark next to “Built-in Ethernet”. Click the button “Apply Now” (located in lower right corner).
  4. Wait 5 seconds, then enable the NIC, by placing a checkmark next to “Built-in Ethernet”. Click the button “Apply Now” (lower right corner).

For Leopard, Lion, and Yosemite:

  1. Open System Preferences => Network.
  2. Click on “Ethernet” in the list on the left. Click on the gear button (it’s below the list on the left).
  3. To disable the NIC, elect “Make Service Inactive”. Click the button “Apply”.
  4. Wait 5 seconds, then enable the NIC by clicking on the gear button again and selecting “Make Service Active” this time. Click the button “Apply”.

Getting the IP address and MAC address and running "arp -a"

To get the IP address and MAC address:

  1. Open System Preferences => Network.
  2. For Tiger: Click on the menu next to “Show” and select “Built-in Ethernet”. For Leopard, Lion, and Yosemite: Select “Ethernet” in the list on the left and click “Advanced”.
  3. Under the TCP/IP tab, record the IP address (if it’s blank, leave a note saying that it’s blank).
  4. For Tiger: Under the Ethernet tab record the Ethernet ID (this is the MAC address). For Lion and Yosemite: the MAC address will be under the "Hardware" tab.

Arp is a Unix command used to identify network-connected computers, routers, etc. To run "arp -a":

  1. Open Macintosh HD => Applications => Utilities. Find “Terminal” and double-click it.
  2. Type in arp -a
  3. Press enter (or return) on the keyboard.
  4. Record the result. This will give the IP address and MAC address of the router, and may be used by SR or LNS to determine if there’s a Rogue DHCP server in the customer’s building.

Another way for checking the IP and MAC address: Click on apple logo (upper left corner) => "About this Mac"=> "More Info" => (for Lion and Yosemite) "System Report" => "Network" => "Ethernet". (Shows both IP and MAC address). Note: on Yosemite, there is no "More Info" tab.

Other troubleshooting steps

  1. Find out what’s the OS[1]. E.g. Tiger (10.4), Leopard (10.5), Lion (10.7), Yosemite (10.10). Older OSs can be troubleshot like Tiger.
  2. Find the status of the NIC: Open System Preferences => Network. NOTE: In 10.4 you need to select "Network Status" from the 2nd drop-down menu to be able to look at the status of the NIC. In 10.5 the status is displayed when you select "Ethernet" from the list on the left.




"Built-in Ethernet is currently active and has the IP address [see list of IPs below]" Possible causes: Should have a live connection. If the customer still cannot access the internet, there may be a proxy server, manually entered DNS address or a 3rd party firewall. Solutions: Quit and re-open browser. Try visiting www.middlebury.edu (if the registration page appears, register the computer). Renew lease. Create a new location. Disable NIC / enable NIC. Try different browser. Reboot. Disable 3rd party firewalls (they are rare on Macs but do exist, e.g. Little Snitch, NetBarrier, Norton etc.). Invite customer to LIB202.

    1. "Built-in Ethernet is currently active but has a self-assigned IP address" OR"The cable for Built-in Ethernet is connected but your computer does not have an IP"Possible causes: The computer detected a cable, a jack, and some connection, however, it cannot talk to the DHCP server. Loose cable. Bad cable. Bad card.Solutions: Ensure that the cable is firmly plugged into the network card and a live jack. Create a new location. Try a different jack. Try a different cable. Reboot. Invite customer to LIB202.
    2. "The cable for Built-in Ethernet is not plugged in"Possible causes: The cable may be unplugged/loose on one end. The cable may be bad. The network card may have failed. Solutions: Ensure that the cable is firmly plugged into the network card and a live jack. Create a new location. Try a different jack. Try a different cable. Reboot. Invite customer to LIB202.
  1. Check the IP address. Refer to Network Troubleshooting to see what various IP addresses can tell you.

Information that we must have in a ticket

If you still haven’t resolved the issue, get some information from the customer and create a ticket:

  • Name and location (building, room #). Make sure we have their extension or cell #.
  • Jack ID (it’s on a silver or white tag around or ON the jack, e.g. "A-0-12").
  • 'IP address, MAC address and the result of running the "arp -a" command.



  1. <sup>Find OS version: Click on apple logo in top left corner of screen, select "About this Mac" and look in middle of the pop-up.</sup>
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