There is no "ethers" file by default, so indeed you need to create it yourself. I just tested this on Wireshark 2.6.7 and can confirm that it does work with the following caveats:
- The "ethers" file will only be read at the startup of Wireshark (so reloading a file or reading a new one will not load it, which one might consider a bug)
- The "ethers" resolving is not configuration profile aware, this means the "ethers" file in your default personal preferences folder will be used (and it will be used with all profiles). "ethers" files in Configuration profile directories are ignored (which one might consider a bug).
The file format of the ethers file is:
xx:xx:xx:xx:xx:xx host-xxx
yy:yy:yy:yy:yy:yy host-yada
