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Start a systemd Service on the First Connection (TCP Socket Edition)
Configure systemd to keep a TCP port open at all times while starting the backing service process only when the first connection arrives.
Challenges
Focused, hands-on problems for sharpening your DevOps and server-side skills. Some teach specific concepts while others mirror real-world scenarios. Every challenge includes hints, feedback, and automated solution checks.
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Make One Echo Server Work with Both TCP and Unix Sockets
Make a single echo server listen on either a TCP socket or a Unix domain socket, selected by its command-line argument. The challenge illustrates that the same stream-socket workflow works with two address families (AF_INET and AF_UNIX).
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Write a TCP Client for a Chat Server
Write a TCP client to hold a back-and-forth conversation with a "chat" server: send a line, read the reply, send another line - repeat until the session is over. A hands-on lesson in designing an application protocol on top of a byte-oriented TCP stream.
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Write a TCP Client for a Telemetry Server
Write your first TCP client for a push-only telemetry server that starts sending sensor readings as soon as you connect. Likely the easiest way to get started with TCP socket programming.
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Write a TCP Echo Server From Scratch
The Hello World of network programming: implement a tiny TCP echo server in the language of your choice.
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Classic Sysadmin Task: Which Port Is a Service Listening On?
Test your Linux and Networking skills by identifying which port a service is using. Sounds easy? Perhaps, but be careful - you only get one shot!
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Classic Sysadmin Task: Which Process Is Listening on a Port?
Test your Linux and Networking skills by pinpointing a process that is listening on a given port. Sounds easy? Perhaps, but be careful - you only get one shot!