This is meant to be the first part of a 3-part series discussing the space & types of IP addresses, with a particular focus on what has changed between IPv4 and IPv6. In this first post I’ll take the audience through a historical tour of some developments within the IPv4 address space.

In a second part I’ll discuss the properties of different types of addresses from a routing and from a security perspective, both in the IPv4 and in the IPv6 space. In the third part we’ll look at the implications of deploying IPv6 in certain networks based on those differences, e.g. “how to handle ACLs and IP address based log analysis approaches in a dual-stack network where systems have one RFC 1918 IPv4 address and multiple IPv6 GUAs?” (for specific reasons the latter two parts might be published on another medium though). In any case let’s start with a brief history of IPv4. The goal here is to understand how we got to the state that we have today.

Coworker: ...and the IP address are compared with a string match.
Me: grinning manically
Coworker: Why are you looking at me like that?
Me: Open up a terminal and type ping 4.2.514 and hit enter.
Coworker: ...what's the fourth number?
Me: grin widens Just hit enter.
Coworker: WTF!?

Here's the point of the whole thing. The IETF people, when they were thinking about IPv6, saw this mess getting made - and maybe predicted some of the additional mess that would happen, though I doubt they could have predicted SDN and wifi repeater modes - and they said, hey wait a minute, stop right there. We don't need any of this crap! What if instead the world worked like this?

In this tutorial, learn to manage the persistent network configuration of your Linux host. Learn to:

• Understand basic TCP/IP host configuration.
• Configure Ethernet and wifi networks using Network Manager.
• Understand systemd-networkd.

In this tutorial, learn about TCP/IP network fundamentals for your Linux system. Learn to:

• Understand network masks and Classless Inter-Domain Routing (CIDR) notation.
  +Know the differences between private and public dotted quad IP addresses.
• Understand common Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) ports and services.
• Know the differences between and major features of UDP, TCP and Internet Control Message Protocol (ICMP).
• Know the major differences between IPv4 and IPv6.
• Know the basic features of IPv6.

Thisarticle takesa detailed look at the design principles, the basis for deploying VPN, and the IPSECprotocol concept, providing a description of thegeneral features of IPSECand of the mechanisms required for itsimplementation. This article was speciallyselected for translation bydeveloperWorks Russia as an example of developerWorks world-wide offerings.