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Lesson 2 Internet Protocol
Objective Identify the properties of Internet Protocol.

Properties of Internet Protocol in Red Hat Linux

In the realm of network communications, the Internet Protocol (IP) stands as a fundamental pillar, facilitating the transmission of data across interconnected networks. Within the Red Hat Linux operating system, IP operates as an integral component, adhering to a set of distinct properties and configurations. This document delineates these properties, providing a comprehensive understanding for administrators and users alike.
  1. Version: IPv4 and IPv6:
    • IPv4: The fourth version of the Internet Protocol, utilizing a 32-bit address space, resulting in approximately 4.3 billion unique addresses.
    • IPv6: The successor to IPv4, boasting a 128-bit address space, thereby significantly expanding the available address pool.
  2. Addressing:
    • IP Address: A numerical label assigned to each device connected to a network. In Red Hat Linux, IP addresses can be configured statically or dynamically.
    • Subnet Mask: Defines the network portion of an IP address, used for subnetting and facilitating efficient routing.
    • Gateway: The IP address of the network gateway, serving as an intermediary for traffic between different networks.
  3. Address Configuration:
    • Static IP Configuration: Involves manually assigning an IP address, subnet mask, and gateway to the network interface.
    • Dynamic IP Configuration (DHCP): Leveraging the Dynamic Host Configuration Protocol to automatically obtain IP configuration from a DHCP server.
  4. Routing:
    • Routing Table: Maintains a list of routes, directing the Linux system on how to reach different network destinations.
    • Routing Protocols: Utilized for determining the optimal path for data transmission across networks.
  5. Interface Configuration:
    • Network Interfaces: Represent the hardware network adapters in the system. In Red Hat Linux, interfaces are configured in configuration files located in `/etc/sysconfig/network-scripts/`.
    • ifconfig and ip Commands: Utilized for viewing and configuring network interface settings.
  6. Domain Name System (DNS):
    • DNS Configuration: Specifies the DNS servers that the Linux system should use for resolving domain names to IP addresses.
    • /etc/resolv.conf: The configuration file where DNS server addresses are stored.
  7. Security and Firewall Settings:
    • iptables and firewalld: Tools for configuring packet filtering rules, ensuring secure and controlled network communications.
    • TCP Wrappers: Utilized for allowing or denying network services by IP address or network range.
  8. Network Protocols:
    • TCP/IP: The suite of protocols that IP is a part of, ensuring reliable, ordered, and error-checked delivery of data.
    • UDP/IP: Another protocol within the suite, used for simpler, connectionless data transmission.

Understanding the properties of the Internet Protocol within Red Hat Linux is imperative for administrators aiming to ensure robust, secure, and efficient network communications. By mastering IP configuration, addressing, routing, and security settings, administrators can harness the full potential of IP, ensuring that the Linux systems under their purview remain seamlessly connected and resilient in the face of network demands.

Imagine you wake one morning in a strange land where everything is written in a language you do not understand. As you venture out, you quickly find you cannot accomplish even basic tasks. Language is a protocol, and its rules tell us how to interpret what others say. The Internet has a protocol too, and its rules make sure data gets from computer to computer.

Internet Protocol

Internet Protocol (IP) underlies all communication over the Internet. It is responsible for:
  1. Describing an addressing mechanism for Internet computers
  2. Breaking data up into manageable pieces and moving them from source to destination

Internet Protocol version 4 (IPv4) became standard in 1981. Today, IP version (IPv6) is gaining acceptance as the next generation IP standard.


When you send data (email, for example), Linux breaks the data into little pieces called packets[1]. Every packet contains information on where it's going (destination address), where it came from (source address), and a data payload.

Gateways: Intermediate gateways route the IP packet to its destination host. Once there, the operating system reassembles all the packets into one unit and gives it to the appropriate program.

Connect RedHat Linux to TCP/IP-based network

To connect Red Hat Linux to any TCP/IP-based network, such as the Internet, a private intranet, or a company extranet one must understand the language of protocols. The differences in how you connect have more to do with the network medium you use (that is, LAN router, cable modem) than they do with whether you are connecting to the public Internet or a company's private network (intranet). Connections to the Internet described in this module include a simple dial-up connection from your own Red Hat Linux system. The most popular protocols for making dial-up connections to the Internet are Point-to-Point Protocol (PPP) and Serial Line Internet Protocol (SLIP). This module focuses on PPP and also builds on the procedures which were previously discussed for creating your own Local Area Network (LAN) by teaching you how to connect your LAN to the Internet.
We first provide an overview of the structure of the Internet, including descriptions of domains, routing, and proxy service. It then discusses how to connect your Red Hat Linux system to the Internet using PPP dial-up connections. For those who want to connect a LAN to the Internet, it describes how to use Red Hat Linux as a router and set it up to do IP masquerading (to protect your private LAN addresses). Finally, this module describes how to configure Red Hat Linux as a proxy server, including how to configure client proxy applications such as Chrome and Firefox.

IP is a simple protocol, and thus does not take address all the possible problems in delivering messages. For instance, Internet Protocol can not:
  1. Guarantee packet delivery
  2. Guarantee packets arrive in the order they were sent
  3. Establish a reliable connection between destination and source
Other protocols, which you will learn about in the next few lessons, build on Internet Protocol and make it more reliable.
The next lesson describes an IP address.

[1]Packet: A unit of information, usually composed of two parts: a header with controlling information and a body with actual information.
[2]Gateway:An entrance into another network, responsible for routing packets into its own network or onto a peer network.