Self-Assigned IP on Ethernet (en0)

ethernetNetwork

Past few days my internet has been automatically getting a Self-Assigned IP on en0. I heard it does this when it can't retrieve a DHCP Server from the ISP.

I've tried these solutions below.

  1. Deleted com.apple.alf.plist
  2. Deleted NetworkInterface.plist
  3. Reset Ethernet Configurations

When I connect to my ISP to get the Router, Subnet and IP settings does it take the system's Mac Address? because changing the last digits of my Mac Address always did the trick but not anymore.

I connected the same Ethernet wire to another MacBook and it connected successfully.

Best Answer

This looks like a basic networking issue where you might need some knowledge to sniff the packets on en0 using tcpdump.

The things that are known to prevent DHCP from reaching the OS are:

  1. Firewalls (OS X, Little Snitch type, malware, and/or internet firewall like Symantec and others)
  2. Network setup where the DHCP server only sends addresses to machines that are cleared for the network

You seem to have done some of the easy troubleshooting, and I personally don't ever like deleting some plist but not all plist since there are many keychains, system plist, ByHost plist and others so you could actually make a problem partially deleting information on networking.

The one thing I would do is re-connect the known machine and record the IP address that gets assigned and swap in the "suspect" machine and force the IP to be the same. If you get network connectivity then you are on the right track with DHCP issues.

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