The other day I was reading about piping on Unix with |, and while creating a new .md file for this blog post, I used cp 2025-07-13-academia-goodbye.md 2025-07-14-network-games.md | subl 2025-07-14-network-games.md in my Mac terminal. Anyway, I was feeling pretty smart - until ChatGPT pointed out that this was not necessary because “cp carries nothing”. Basically, in this situation | does nothing, except enabling me to write the command in one line. Well… you learn…

Network curiosities

While learning networking on TryHackMe a few days ago, I learned about ARP packets and network scanning, MAC addresses, and of course I was curious to see what devices are currently attached to my home network, so I did a quick sudo arp-scan. What I found was suprisingly interesting. First of all, I had several unknown devices on my network, and secondly, some devices appeared and disappeared between scans. Below is the image which illustrates this behaviour.

ARP scan results
ARP-scan showing connected devices on my LAN

We can see that there are multiple unknown devices on my network. So… what? 😄 Next, I used nslookup to actually find the names of the devices, and voilà - all those locally administered “unknowns” turned out to be Android phones!

nslookup results
nslookup results showing the names of "unknown" devices

Lessons learned

  1. Android phones show up as unknown when using arp-scan.
  2. Android phones connect and disconnect from the network - probably to conserve battery power.
  3. Piping with | is sometimes redundant. 😂

Next steps

I will continue learning about networks. I want to deepen my knowledge to be able to use it in real-life, especially at home. Also, I plan to build a Python-based network scanner that will be able to:

  1. Scan my network every 30 seconds.
  2. Log the scans into a .txt file.
  3. Alert me if unknown devices appear on the network.

This will be an exercise in Python, in networking, and in cybersecurity.

Post-scriptum: This was a quick exercise, I am aware there are also other devices on my network that could be looked up and discovered. That’s for next time.

Until next time, happy network scanning.