Keep Your Hostname on Public WiFi Networks Apr 22, 2011

Have you ever joined a public WiFi network only to have your hostname change to something seemingly random? While hacking with Wayne Seguin last night on a hotel network, he ran into this exact problem on OS X, and it reminded me of a workaround that I learned about a few years ago.

Some networks have their DHCP server configured to assign hostnames for all machines that connect to it. OS X respects this and will reassign your hostname automatically. I suspect this is to help avoid name collisions on the network, but if you want to prevent OS X from doing this, there is a workaround.

Open /etc/hostconfig and add the following line:

HOSTNAME=<your-preferred-hostname>.local

Afterwards, OS X will no longer respect the DHCP command to reassign the hostname. This is especially helpful if you have scripts that rely on your hostname being set to something specific.

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