Ubuntu 16.10 and Zeroconf

I don’t do enough system admin to enjoy it when I do. (Does anyone?)

When you upgrade Ubuntu, you lose a lot of the software you’d installed. There’s a list of system admin tips that I try to remember here. (Which reminds me, I should find a better home for it for when Twitter dies.)

I couldn’t resolve names of Macs in my local network. I should point out what a shame it is that Mac addresses aren’t the same thing as MAC addresses, since Google as my primary system admin resource.

That’s the work of avahi-daemon and friends (a/k/a Zeroconf and Bonjour). For awhile I thought that something had broken there. But eventually, I figured out that was working, i.e., the problem lay elsewhere.

I wondered if they’d added a firewall to 16.10. They did (or, for all I know, they’ve always had one) called ufw (more here), but it’s (still) not enabled by default. If that ever changes, I can learn what to do about it here.

After about an hour, I found out there is something called nss-resolve. Which is actually a pretty clever idea. Except it wasn’t working. Its configuration file is well documented here. Good luck figuring that out.

Finally, I just compared my 16.10 /etc/nss-switch.conf file with the one from a working installation of 16.04.1. HAH!

Not only was there a difference, it gave me a string I could Google. That brought me to this: http://askubuntu.com/questions/837982/how-to-configure-local-dns-lookup-in-ubuntu-16-10

It also brought me to this: https://github.com/systemd/systemd/issues/4157, which (if I read it correctly) says that I should go ahead and use the string from 16.04.1 that works instead of the one from 16.10 that doesn’t.

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