How to use dns-sd
Today I was troubleshooting why some of my smart home devices weren’t showing up on my Wi-Fi network.
Turns out, not all of them are going to show up correctly. In order to find them, you may need to run some mDNS queries with dns-sd installed by default on macOS.
First, you can query what types of protocols are available to you.
dns-sd -B _services._dns-sd._udp | awk '{ print $NF }'
After some filtering/cleanup, my list looked like this.
_sleep-proxy
_raop
_companion-link
_meshcop
_srpl-tls
_matter
_ltpdu
_hap
_spotify-connect
_sleep-proxy
_matter
_meshcop
_ltpdu
_hap
_srpl-tls
_rdlink
_aqara-setup
_hap
_pdl-datastream
_printer
_ipp
_scanner
_http
_uscan
_raop
_companion-link
_airplay
You may query each one of them with the following command
dns-sd -B _ltpdu._udp.
and may get something like this in response
Instance Name
Nanoleaf A19 DE0-EB91
Nanoleaf A19 1WWJ
Nanoleaf A19 96M2
Nanoleaf A19 4565
Nanoleaf A19 3R4X
Let’s query one of them
dns-sd -L "Nanoleaf A19 DE0-EB91" _ltpdu._udp.
and we get
Nanoleaf\032A19\032DE0-EB91._ltpdu._udp.local. can be reached at B6A77EC42FDCBA97.local.:5653 (interface 15)
xp=609841E38E704518 srcvers=3.2.0 md=NL67 eui64=B43A31FFFED909F7 id=EB91
Now let’s do another query
dns-sd -G v4 B6A77EC42FDCBA97.local.:5653
We get the follwoing. I removed IP address for security reasons.
Hostname Address TTL
B6A77EC42FDCBA97.local.:5653. <REDACTED> 77
It seems to point to some DigitalOcean server in New York. I guess that’s an investigation for another day.