Working with networking services
In this section, we enumerate some of the most common network services running on Linux. Not all the services mentioned here are installed or enabled by default in your Linux platform of choice. Chapter 8, Configuring Linux Servers, and Chapter 9, Securing Linux, go into how to install and configure some of them. Our focus in this section remains on what these networking services are, how they work, and the networking protocols they use for communication.
A network service is typically a system process implementing an application layer (OSI Layer 7) functionality for data communication purposes. Network services are usually designed as peer-to-peer or client-server architectures.
In peer-to-peer networking, multiple network nodes each run their own equally privileged instance of a network service while sharing and exchanging a common set of data. Take, for example, a network of DNS servers, all sharing and updating their domain name records.
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