Linux › Section J · Network applications and services › Topic J.1
The basics of network services
A web page, a remote login and a name lookup all work the same way underneath: a client program opens a connection to a server program waiting on a port, and the two exchange bytes. Talking to a server by hand, then watching a real client do it, shows exactly where the kernel's job ends and the application's begins.
In this topic
- Clients, servers and services
- Port names and /etc/services
- A TCP service is a two-way byte stream
- Worked example: a request typed by hand
- Encrypted services need a TLS client
- curl: a client that knows the protocol
- Worked example: reading a curl trace
- Where the application layer lives
- Which services is this machine running?
- Common mistakes to avoid
- Key takeaways
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