Two Barracks at the Main Base

created: 2023.02.01. 13:53 · modified: 2023.02.01. 14:24 ·  · license

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Lately, I’ve been working on a side project alongside my startup team’s work. The frontend and backend have each come far enough that it’s time to connect them (I’ll probably write about what the project is when I release its MVP). I didn’t want to pay for EC2, and sharing the Raspberry Pi that runs gunh.ee seemed complicated, so I reinitialized and booted up the other Raspberry Pi I’d set aside because of an Ethernet cable issue in my previous post. The Ethernet interface still isn’t showing up, but speed isn’t an immediate concern, so I’ll deal with that later.

To distinguish inbound traffic directed at our home’s single public IP address, the two servers need to use different external ports. Port numbers have conventional uses: 22 for SSH, 80 for HTTP, and 443 for HTTPS, for example. So I left those external port numbers as they are for the gunh.ee server, added 10000 to each for the side project, and configured the router to translate traffic headed for the side project to the corresponding conventional internal port numbers by subtracting 10000.

Every time I do something like this, I’m reminded how much taking Intro to Computer Networks has helped. Thank you, Professor Moon.

I already went through the Ubuntu setup process when setting up gunh.ee, but there are still a few points that trip me up sometimes, so I’ll jot them down here.

(On a Mac)

The entire process of downloading an Ubuntu image, writing it to an SD card, and booting from it is described in detail here.

To format the SD card, select it in Disk Utility, click ‘Erase,’ and choose ‘MS-DOS (FAT32)’.

To write the downloaded image file to the SD card, use the following command. Leave the image file compressed.

sudo sh -c 'gunzip -c ~/Downloads/< image file > | sudo dd of=< drive address > bs=32m'

Once it has booted, enter your Wi-Fi details in /etc/netplan/50-cloud-init.yaml as described here, save the file, and reboot. /etc/network/interfaces is a file used by ifconfig, but ifconfig isn’t installed in the initial Ubuntu setup, so entering the information there won’t help.