Using Mikrotik's Router to Detect Power Outage

Before I had CyberCard, I still had a need to monitor if my system was running off the UPS power. If my server could detect power out and shut down other devices, my battery life would keep server up for longer.

If you have Mikrotik’s router with two power supplies and an SSH connection to the same there is a trick you can use - Mikrotik can show you each power supply state. If you take care to plug one power supply into the UPS and the other one into the non-UPS outlet, you suddenly have a detector.

ssh -i ~/.ssh/id_rsa admin@router.home "/system health print"
            voltage: 23.6V
            current: 426mA
        temperature: 50C
  power-consumption: 10W
       psu1-voltage: 24.4V
       psu2-voltage: 0V

Even better, the voltage doesn’t go immediately to 0 V as soon as power is out so there is a delay built-in. So, script is as easy as detecting 0V on the output. Something like this.

ssh -i ~/.ssh/id_rsa admin@^^router.home^^ "/system health print" \
  | egrep 'psu[12]-voltage' | grep -q '0V' && echo "Do Something!"

PS: If you’re interested in the whole script around this, you can download it here.

Sendmail via GMail on Ubuntu Server

I finally decided to migrate my Wordpress onto Ubuntu 20.04 only to discover e-mail I configured via Smtpmail stopped working. That meant my WordPress and various PHP and command line tools couldn’t use Google’s e-mail relay to deliver e-mails to my Inbox. It was time to setup my server to use Google’s SMTP again. And this time I decided to go with postfix.

Installing postfix usually involves a GUI asking a few questions. However, you can use debconf-set-selections to preload the answers. Make sure to be the root used (sudo su -).

debconf-set-selections <<< "postfix postfix/main_mailer_type string 'Internet Site'"
debconf-set-selections <<< "postfix postfix/mailname string ''"
apt-get install --assume-yes postfix libsasl2-modules

Once installed, we need to provide credentials in /etc/postfix/sasl/sasl_passwd.

unset HISTFILE
echo "[smtp.gmail.com]:587 ^^relay@gmail.com^^:^^password^^" > /etc/postfix/sasl/sasl_passwd
postmap /etc/postfix/sasl/sasl_passwd
chmod 0600 /etc/postfix/sasl/sasl_passwd /etc/postfix/sasl/sasl_passwd.db

Finally we need to update /etc/postfix/main.cf for authentication options.

sed -i 's/relayhost = /relayhost = [smtp.gmail.com]:587/' /etc/postfix/main.cf

cat <<EOF >> /etc/postfix/main.cf
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd
smtp_sasl_security_options = noanonymous
EOF

And that’s pretty much it. The only remaining thing is to restart postfix:

systemctl restart postfix

To test if it works, just use sendmail.

echo "Subject: Test via sendmail" | sendmail -v ^^youremail@example.com^^

[2022-06-16: As of 2022-06-01, it’s not possible to use your Google email and password directly. However, you can still follow this guide and use App Password instead.]

The Cost of CyberCard

After publishing text about the CyberCard project I got the question from a friend. Wasn’t it cheaper to buy Jeff Mayes’ interface driver then to build my own?

Answer is yes - at $30 that board is cheap. But that’s not all. Even the original RMCARD205 at $150 is cheaper than what I spent.

First of all, there were 4 revisions. The first revision was a bit too large. Manually filing PCB did the trick for the troubleshooting but I wanted to have revision B with the correct width. While width was now correct, I accidentally shortened it a bit. And yes, this brought me to the third revision. For that revision I also changed MCP2221A to SOIC package. It wasn’t strictly necessary but I figured having all three ICs in SOIC looked nicer than having different package styles on the same board. The last revision D was just a bit more fiddling with design without any major change. Yes, there were some other changes but this was a gist of it.

Considering each revision was around $25 in PCB cost (OSHPark) and I spent about $50 in parts for them, project was more expensive than official RMCARD205 even without accounting for my time. Since the first version was actually working, you can view all the time and money spent afterward as wasted.

But I disagree. From the moment I started working on it I knew it would end more expensive than the original part. Even for the first board I spent more money in PCB and parts than what Jeff’s adapter would cost with shipping. I found this board to be the perfect project: it would result in something useful, it was simple enough that I could work with it whenever I had some spare time, cheap enough that it wouldn’t break the bank, and an excellent chance to setup PIC16F1454 as an USB device.

I was eyeing PIC16F1454 for a few years now (I still have sample from Microchip from when it was originally announced) but I never got around to. When I first started with the board design I noticed MCP2221A USB-to-serial bridge was compatible with 16F1454’s footprint. If I was a betting man, I would have said that MCP2221A was nothing other than PIC16F1454 with the custom code. This project gave me a reason to get into this interesting PIC and do some USB programming.

I actually paid not for the final board - no matter how well it works. I paid a good money to keep me entertained and to fill my free time. And it was worth every penny.

SignTool Failing with 0x80096005

After creating a new setup package I noticed my certificate signing wasn’t working. I kept getting error while running the same signing command I always had.

sign -s "My" -sha1 $CERTIFICATE_THUMBPRINT -tr ^^http://timestamp.comodoca.com/rfc3161^^ -v App.exe
 SignTool Error: An unexpected internal error has occurred.
 Error information: "Error: SignerSign() failed." (-2146869243/0x80096005)

A bit of troubleshooting later and I narrowed my problem to the timestamping server as removing /tr option made it work as usually (albeit without the timestamping portion). There were some certificate changes for the timestamp server but I don’t believe this was the issue as the new certificate was ok and I remember their server occasionally not working for days even before this.

And then I remembered what I did the last time Comodo’s timestamp server crapped out. Quite often you can use other, more reliable, timestamp server. In my case I went with timestamp.digicert.com.

sign -s "My" -sha1 $CERTIFICATE_THUMBPRINT -tr ^^http://timestamp.digicert.com^^ -v App.exe
 Successfully signed: App.exe

PS: This same error might happen due to servers refusing SHA-1.

Connecting to CyberPower OR500LCDRM1U UPS Serial Port

To keep my file server and networking equipment running a bit longer in the case of power outage, I have them connected to CyberPower OR500LCDRM1U UPS. It’s a nice enough 1U UPS but with a major issue - no USB connection.

Well, technically there is an USB connection but it doesn’t work under anything else than Windows. If you want it working under Unix, the only option is RMCARD205, optional network module upward of $150. Essentially doubling the price of UPS.

And it’s those internal connections Jeff Mayes took advantage of for a simple serial interface. If the only thing you want is a serial interface, you might as well go with his interface driver as price is really reasonable.

However, his boards require you to either have a serial port or to have an USB-to-serial cable. What I wanted was direct USB connection. Since there was nothing out there, I decided to roll my own.

Since I had an UPS locally, it was easy enough to get physical dimensions. Unfortunately just measuring them wasn’t sufficient as they narrow as you go deeper so my first assumption of 3.1x1.7 inches was a bit off. Due to that and bottom connector that was a bit shallower then expected, the final board dimensions were more like 71x43 mm. It took a bit of probing to find the 4 signals I needed were grouped together with GND and RX on the bottom while TX and 12 V were on the top.

Connecting the appropriate serial connections to UART-to-USB converter like MCP2221A was a minimum required but I felt a bit queasy about connecting it directly to my computer. Therefore I decided to isolate the UPS interface from the computer. For this purpose I used Si8621 digital isolator offering 2,500 V isolation which was probably an overkill but allowed me to sleep better.

The last physical piece needed was a cover for card to avoid having a large opening in the back of my rack. While risk of anything getting inside is reasonably low, making a 3D printed cover was easy enough. It took a few tries to get cover design right in TinkerCAD but it avoided having a gaping hole.

If you are interested in making one for yourself, check project page for all the files.