formats

Clear or Flush Arp Cache in OS X

Published on August 3, 2011, by + in osx.




To clear or delete the arp cache in Mac OS X, crack open a terminal and issue the following command:

$ sudo arp -a -d





clear_arp_osx

Done!


Thanks Theo

5 Responses

  1. Louie_de_palma

    I tried using “arp -a -d” and indeed it stated that each entry was deleted, however the cache was full when doing an “arp -a” right after. No requests made to stations that should of prompted an ARP. I checked with Wireshark and then to be sure I disconnected a node that was in the cache, I then flushed the cache but it is still there???? Baffling…

  2. Sean Fisk

    @Louie_de_palma Got the same results as you did. I didn’t use Wireshark, but again, I didn’t do anything that would have prompted a request. I also ran arp -a -d; arp -a (delete cache then immediately show cache) with the same results. I’m confused too.

  3. Louie_de_palma

    I forgot about this but will be happy of someone provides an answer. At least it’s not just me…

    • someone

      hi there,

      the arp cache should be filled up with the information of the
      established connections. Please compare to the output of:
      netstat | fgrep ESTABLISHED

      HTH!

  4. Sake

    Hi, I ran into the same problem. Google brought me here, but I was not able to find a solution. So I started to experiment. It seems that OS/X will not delete an arp entry unless you specify which interface to delete it from (at least on my Snow Leopard).

    So you can use "sudo arp -d 192.168.1.1 ifscope en1" or equivalent :-)

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