How to Change an OpenBSD Server's Hostname Thoroughly

Mar 09, 2023 @ 7:54 pm

Changing host names on Unix is surprisingly complicated and implementation-specific. Even though there is a “hostname” command in most (all?) Unices, it generally doesn’t change everything.

After recently renaming an OpenBSD system, I thought I’d make a quick howto. In this example, I’ll change a server the new name cthulhu.example.com.

First, use the hostname command:

# hostname cthulhu.example.com

Next modify /etc/myname to have the same information:

# cat /etc/myname
cthulhu.example.com

Update /etc/hosts, replacing the old hostname with the new.

Finally replace the host keys:

# cd /etc/ssh
# rm -f *_key *.pub
# ssh-keygen -A

And that’s it for the base system. Consider other software you might have installed such as mail, etc.

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raindog308

Dread Lord of LowEnd Content at LowEndBox

I'm raindog308, techno polymath and long-time LowEndTalk community Administrator. My technical interests include all things Unix, perl, python, golang, shell scripting, vintage operating systems such as MVS, and relational database systems such as Oracle, PostgreSQL, and MySQL.

I also enjoy using LEBs! I have an empire of little guys for VPNs, larger guys for apps, and big guys for databases and storage. When I'm not in front a screen I'm into German Shepherd dogs, quality knives, target shooting, theology, tabletop roleplaying games, and forest hiking.

I enjoy writing technical articles here on LowEndBox to help people get more out of their systems. You can find me on LowEndTalk @raindog308

1 Comment

Cuphead:
I’m confused about a few things and haven’t made this change yet. Can you share a more detailed cover letter?
March 9, 2023 @ 11:22 pm | Reply