Well, just a few months into using a Thingino-flashed WyzeCam3, I noticed that one of the units had stopped responding.

I could see it connecting to the network (or at least taking a DHCP lease from the router), but all connection attempts failed. The LED was lit, but I couldn’t tell what it was doing. I shut it down, and checked the SD Card — the last motion it had captured was from fifteen hours ago, although there was plenty of room left on the card. Something was weird.

I powered it back up, confirmed that it was connecting to the network, and checked to see if it was actually offering any network services. This was where things got weirder:

#nmap -Pn 192.168.x.x
Starting Nmap 7.99 ( https://nmap.org ) at 2026-08-05 08:49
Nmap scan report for MuhCam.lan (192.168.x.x)
Host is up (0.051s latency).
Not shown: 999 filtered tcp ports (no-response)
PORT   STATE SERVICE
53/udp open  ssh

Nmap done: 1 IP address (1 host up) scanned in 11.03 seconds

Say what!? Running sshd with UDP listening on the DNS port!? I’ve seen strange configurations in my time, but I haven’t seen that. Also, trying to ssh to that port didn’t work.

The fact that it connected to WiFi told me that it was mostly booting, but this made me think there was some corruption in the config files. It made no sense.

I was getting ready to open it up and see if there was a way I could hook up to a serial console or some other desperate measure, when I saw it flash the IR LEDs briefly, but not very brightly. This roused suspicion. Out of curiosity, I swapped the USB cable that it uses for power. Slightly different results now:

#nmap -Pn 192.168.x.x
Starting Nmap 7.99 ( https://nmap.org ) at 2026-08-05 09:14
Nmap scan report for MuhCam.lan (192.168.x.x)
Host is up (0.029s latency).
Not shown: 999 filtered tcp ports (no-response)
PORT STATE SERVICE
123/udp open ssh

Nmap done: 1 IP address (1 host up) scanned in 10.19 seconds

OK, so now it says that sshd is listening on the NTP port? So whatever was corrupting the config files was not a one-time thing. Was it filesystem issues? Memory corruption? Failing hardware?

I thought Id’ try one more thing. I unplugged it, and plugged the original USB cable into a different A/C adapter.

What do you know? It came up cleanly, with the configuration intact! It was the power supply!

For the record, the normal nmap output looks more like:

#nmap -Pn 192.168.x.x            
Starting Nmap 7.99 ( https://nmap.org ) at 2026-08-05 09:27
Nmap scan report for MuhCam.lan (192.168.x.x)
Host is up (0.0053s latency).
Not shown: 994 closed tcp ports (conn-refused)
PORT     STATE SERVICE
22/tcp   open  ssh
53/tcp   open  domain
80/tcp   open  http
443/tcp  open  https
554/tcp  open  rtsp
8080/tcp open  http-proxy

Nmap done: 1 IP address (1 host up) scanned in 1.72 seconds

I clicked on a link to a web page I host on a Rocky Linux 9.7 VPS, and my browser stalled. That seemed strange, so I ssh-ed in to see if the web server was running correctly. ssh timed out.

So I used the VPS provider’s web-based console to log in, and found the networking was all dead. That was unexpected. After trying to remember the service name in this flavor/version, I executed systemctl restart NetworkManager.service and it was back … until I did a dnf update. Then it locked hard, and even the web-based console couldn’t log in for a while.

Tech support helped me track down the problem.

The VPS “only” had 2G of RAM, and that’s not enough on a modern Linux system to run a web server, database, and package manager. The dnf package manager subsystem was consuming all available memory when computing dependencies, and being killed by the oom-killer, leaving the system in weird states.

I ended up resizing the VPS to a mighty 4G RAM. It’s a few bucks more a month.

Makes me think of my first Linux box, which ran Debian Hamm in what I seem to think was 6M of memory.

I keep some directories synchronized between my notebook and desktop with rsync. After upgrading my desktop to Mac OS 15.4.1, I started getting errors:

[sjg@BigThud 2025-04-21 13:01:05] ~/Documents/Backup
$ rsync -auP . sjg@10.3.2.xx:Documents/Backup
(sjg@10.3.2.xx) Password:
rsync: failed to set times on "/Users/sjg/Documents/Backup/Whatever": Operation not permitted (1)

Interestingly, ssh also showed an error:

[sjg@BigThud 2025-04-21 13:04:29] ~/Documents/Backup
$ ssh sjg@10.3.2.xx "ls /Users/sjg/Documents/Backup/Whatever"
(sjg@10.3.2.xx) Password:
ls: /Users/sjg/Documents/Backup/Whatever: Operation not permitted

On the desktop, I look again at Documents/Backup/Whatever, and the permissions are fine. What gives?

To make a long story short, something in the latest update on the desktop changed sshd‘s full disk access permission. Looking at System Preferences > Privacy & Security > Full Disk Access, sshd-keygen-wrapper was checked, so it should have been enabled. I tried toggling that, but it didn’t help.

Apparently, the sshd-keygen-wrapper was pointing at an old version or something? I had to go into System Preferences > General > Sharing and turn Remote Login off then on again, then go into System Preferences > Privacy & Security > Full Disk Access and re-enable sshd-keygen-wrapper.

Et voilà, I could ssh and rsync again!

There’s gotta be a better way. But after a horrible upgrade process for a horrible commercial open-source product, I need to see which sub-directories from the old installation are missing in the new one. Don’t ask. I’ve literally been having nightmares about this upgrade.

Anyway, given tree1 and tree2 under some common point, I want a list of directories that exist in tree1 and don’t exist in tree2.

Here was my clumsy way of solving the problem.

cd tree1
find . -type d -print | sort > ../dirs_old
cd ../tree2
find . -type d -print | sort > ../dirs_new
cd ..
comm -23 dirs_old dirs_new

So your site was using too much bandwidth, and you converted all those animated .gif images to .webp using the WebPShop plugin.

But how many bytes have you actually saved? The command line will tell you:

ls -l *.gif | awk '{ print $5 }' | paste -sd+ - | bc 

ls -l *.webp | awk '{ print $5 }' | paste -sd+ - | bc 

Of course, this assumes that all the files in the current directory are the images and their conversions, and there aren’t a bunch of other files with one of those extensions. If that’s not the case, you’ll need to be more specific than *.extension in the ls command.