Home Knowledge Blog Contact

Decentralized Web project

dWeb tutorial - local and global IP address

1. Introduction

This article covers some basics of Internet Protocol (IP) communication. It is written in a way to be understandable by ordinary / non-technical person.

Previously, me - an experienced programmer did miss, or was not clear on some details in the IP communication. So, even a technical person can benefit and get clarity.

Throughout tutorial articles important information is marked in bold font.

2. Local IP address

A computer and some other devices (phones,printers) usually has a network card. When the computer is powered on , booted and network software enabled the network card connects to a modem/switch/router device which assigns to the computer an IP address. In this article we call this - local IP address.

Technically this address is also called 'private' network address.

The address assigned is specific and is one of the following - 192.168.0.xx , or 10.xx.xx.xx , or 172.16.xx.xx .
The 'xx' is actually a specific number - from 0 to 255.

Multiple computers and devices connecting to the same modem/switch/router device are given their own local IP addresses and form a local network.

A simple case of a local network is the home of a person where they form the local network with their WiFi connected laptop computer, WiFi connected printer, and Wifi connected phone. These 3 devices are assigned local IP addresses like for ex. - , and .

More complex cases are the local networks formed - in a coffee shop which may serve access to computers of 1 to tens of customers, or in a library or in a large company which may serve the computers of hundreds of users.

3. Global IP address

The mentioned modem/switch/router device serves as a bridge between the local network and the world wide web / www , also known as the Internet. All of the addresses of the local network become one global IP address. In other words from outside / global point of view all users and devices of the local network appear as a single global IP address.

The computers and devices in the local network still use their local IP address to communicate with each other. One example of this type is the communication between a laptop and a printer through WiFi connection at home.

Even though there is a single global IP address assigned, the modem/switch/router device takes care of routing the web communication requests of each of the 2 users to the appropriate user.

Most of the global / web IP addresses assigned to each modem/switch/router device are static - they do not change.

Small Internet providers may assign dynamic IP address - the addresses assigned to each modem/switch/router device change. For the commercial and national security purposes of tracking user communications, using dynamic IP addresses is discouraged in favor of using static global / web IP addresses.

From the very beginning the global IP addresses assigned were of the type IPV4 - like for ex. . This type allow having around 4 billion unique addresses.

A newer IP addresses type is IPV6 - like for ex. . While IPV6 allows having a lot more IP addresses the IPV4 is still dominant type in use in IP global / web communication.

4. Port used with IP addresses

In addition to IP address, whether local or global, a second parameter called port is used in IP communication.

Every IP communication request and replay use a combination of IP address and port.
Port is a number - from 1 to 65535 .

For ex. the requests on HTTP protocol use port 80 , and requests on HTTPS protocol use port 443 .

Important - The dWeb project use port 12600 .

5. Finding local and global IP addresses

While very basic, this article is a preparation for testing and enabling direct global communication between users.

We did make a program which runs on Windows 64bit, and Linux 64bit. A build for Mac OS X and Android will follow.

The program allows finding local and global IP address. More importantly it finds the type of communication - outward only, or outward and inward.

Additional details on the type of communication - outward / inward will be available in following tutorial articles.

   Support our project - become our patron on Patreon:   Patreon - Decentralized Web