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The TCP/IP Guide for Beginners

The TCP/IP protocol is used by computers to communicate over the Internet. Any device using the Internet – even your intelligent lightbulb – utilizes this protocol. And as you probably know, it’s an acronym for Transmission Control Protocol (TCP) / Internet Protocol (IP).

In fact, TCP/IP is much more than a protocol. It’s a full set of communication protocols that use different layers to specify how the data is broken down into packets, how it is assigned an address, how it travels through the lightning fast Internet lanes, and how it is received. Technical standards are defined and maintained by the Internet Engineering Task Force.


TCP/IP was built by the Defense Advanced Research Projects Agency (DARPA) back in the 70s. The first version of the TCP protocol was published in 1974. Later on, when new versions emerged, TCP was split in two sections: Transmission Control Protocol and Internet Protocol.

To set up a TCP/IP based network you need computers, which serve as interfaces to each network, forwarding data packets back and forth. In addition to this, firewalls, content caching systems and network address translators are also needed.

The Internet Protocol (now at IPv6) section plays two key roles:

– It takes care of all the identification and host addressing needs, by making use of an advanced IP addressing system;

– It routes data packets from the source computer to the destination computer, by making use of all the computers that serve as routers and can be found on the way from source to destination.

As time has passed by, the TCP protocol has evolved. Today, it is able to correct error data, when the errors are minimal. If the errors are numerous, it can automatically ask the router to resend the data packages that can’t be corrected. Additional capabilities include layers that can deal with data congestion, duplicate data packets, and more.

The IP protocol doesn’t rely on a specific piece of hardware or software. All you need to make it work is the proper hardware equipment and a software layer that is able to send and receive data packets over a computer network.

The initial DARPA implementation was requiring two ports for a half duplex-transmission. Later on, the protocol has evolved, being able to use fewer ports, while sending more data. Today, you will only need a port to achieve full-duplex, bidirectional data transportation.

The Internet Assigned Numbers Authority maintains the official port numbers that can be used for specific TCP/IP operations. Despite that, some implementations make use of unofficial, and yet well known port numbers.


System ports have numbers that range from 0 to 1023 and are officially known and approved. Ports ranging from 49,152 to 65,535 are private and cannot be used for standard applications. Nevertheless, they can be used for private purposes, be them temporary or permanent.