Server

Core Idea

A server is a machine or process that waits for requests and responds to clients.

Course Examples

• lf2607.kolamayermakers.org is the SSH server you log into.
• Caddy is the web server in front of learner websites.
• Your site.service becomes a user-owned web service.
• Forgejo is a git server for source repositories.

Machine Versus Process

People say “server” in two ways:

• Server machine: the computer reachable on the network.
• Server process: the program listening for requests, such as SSH, Caddy, or Python’s HTTP server.

When debugging, ask which meaning is relevant.

What Servers Need

• An address or name clients can reach.
• A port and protocol.
• A process listening for requests.
• Permissions and configuration.
• Logs that explain failures.

Common Failures

• DNS works, but no process is listening.
• Process listens locally, but public routing or proxying is missing.
• Service starts, but permissions stop it from reading files.
• Server returns an error, but the client only shows a short symptom.

Proof Check

For your personal service, identify the server machine, server process, port, protocol, and log command.

Docs Pointers

• Run man sshd.
• Read Python http.server documentation.
• Read Caddy documentation.
• Read Client for the other side of the request.
• Read Service, Process, and Sockets for the service process behind a server.