How to clear the ARP cache on Linux?

There are several reasons when you might need to clear your ARP cache. There are two common ways on Linux systems, typically using the arp or ip utility. Depending on your Linux distribution and the availability, we suggest using the ip tool.

Clearing cache with ip

Newer Linux distributions have the ip utility. The ip tool has a more advanced way to clear out the full ARP cache.

ip -s -s neigh flush all

The first -s will provide a more verbose output. By adding one more, we can select the neighbor table. The neighbor table with the ip command equals both the ARP and NDISC cache. Note that the -s options are not available on all versions of the ip command. If it not supported for your version of ip, then simply remove them from the command.

The output of the flush all command will produce the following output.

Screenshot of clearing an ARP cache with ip neigh flush command

The ARP cache is cleared, with verbose output

Clearing cache with arp command

The arp utility does not accept an option to clear the full cache. Instead, it allows to flush out entries found with the -d option.

arp -d

After deleting, have a look with the arp utility again to see the new list:

arp -n

The output of this command will typically show the active ARP entries.

Address          HWtype  HWaddress           Flags Mask     Iface              (incomplete)                       eth0      ether   00:02:9b:a2:d3:f3   C              eth0      ether   00:02:9b:d9:d1:a2   C              eth0

The entry now shows as incomplete, which means the ARP entry will be refreshed when it is needed again.


Depending on your distribution, the ip utility is quicker if you want to flush out the full ARP cache. For individual entries, the arp tool will do the job as quickly. Both tools are available for most distributions, including Arch Linux, CentOS, Debian, Fedora, RHEL, and Ubuntu.

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Relevant commands in this article

Like to learn more about the commands that were used in this article? Have a look, for some there is also a cheat sheet available.


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This article has been written by our Linux security expert Michael Boelen. With focus on creating high-quality articles and relevant examples, he wants to improve the field of Linux security. No more web full of copy-pasted blog posts.

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