characteristics of ipv4

The word “IP ” stands for “Internet Protocol.” An Internet Protocol or IP Address is a unique logical numeric address assigned to every computer, printer, switch, router, or network device. It is the core component of the TCP/IP network.  There is no possibility of a network without an IP address. IP addresses such as 192.168.1.1 uniquely identify every host in the network.  There are two parts of the IP address.

Every device connected to a network, from your smartphone to a web server, relies on an IP address to communicate. Whether browsing the internet or streaming videos, IP addresses ensure data reaches the right destination. This article dives deep into what addresses are, their role in networking, and key concepts like IPv4, IPv6, subnetting, and security. Let’s start with the basics.

Why Are IP Addresses Important?

IP addresses serve two primary functions:

• Identification: They uniquely identify devices on a network, like a phone number for a device.
• Routing: They guide data packets to their destination, ensuring your email or webpage reaches the correct server or device.

Without IP addresses, devices couldn’t communicate, making networking impossible. They’re managed by protocols and organizations like the Internet Assigned Numbers Authority (IANA).

The network part of the IP Address

The network part specifies the unique number assigned to the network and identifies the class of the IP address. All hosts in a network are grouped in a single IP address range, called its net or subnet.

The host part of the IP Address

This is part of identifying the host uniquely in the network. Each host assigns a unique address from the network’s range. Each network has a different address range; routers on layer 3 connect these networks.

Note: For each host on the network, the network part of the address will be the same, but the host part should be different.

How Do IP Addresses Work?

As network devices generate TCP or UDP segments, a header with source IP address and destination IP address, among other information, is added. This PDU (protocol data unit) is called a packet. When a router receives a packet, it looks at the destination address in the header and forwards it to the destination network. The packet may pass through multiple routers before it reaches the destination network. Each router it has to go through is called a hop.

IP address Fields

This field plays a very important role in sending data through different hops. Version 4 is the most used in today’s networking. The Figure below illustrates the header structure of the IPv4 address.

Version

This field shows the version of the IP. For IPv4 address, this value is 4.

Header Length

Header length specifies the size of the header itself. The smallest size is 20 bytes. The figure does not show a variable length’s rarely used options field. Most IPv4 headers are 20 bytes in length.

DS Field

The Differentiated Services field marks packets for different quality-of-service (QoS) levels. For example, data belonging to voice and video protocols is not accepted for delay. The DS field marks packets carrying data belonging to these protocols so that they get priority treatment through the network. On the other hand, peer-to-peer traffic is considered a significant problem and can be marked down to give the best-effort treatment.

Total Length

The total length field specifies the size of the packet. The length contains the header size, including the data size.

Identification

When a device receives a segment from TCP or UDP, It may be required to break the segment into chunks called fragments before sending it out to the network. Identification fields find the fragments that make up the original segment. Each fragment of a segment will have the same identification number.

Flags

Used for the fragmentation process.

Fragment Offset

The fragment offset field identifies the fragment number so that the segment can be reassembled in the correct order.

Time to Live (TTL)

The TTL value is set to the originating host. Each router that the packet passes through reduces the TTL by one. The packet is dropped if the TTL reaches 0 before reaching the destination. This is done to prevent the packet from moving around the network endlessly.

Protocol

The protocol field identifies the protocol to which the data belongs. For example, a value of 6 implies that the data has a TCP segment, while a value of 17 signifies a UDP segment. In addition to TCP and UDP, many protocols can carry data in an IP packet.

Header Checksum

The header checksum field is used to check for errors in the header. For each router and at the destination, a cyclic redundancy check is performed on the header, and the result should match the value stored in this field. If the value does not match, the packet is discarded.

Source IP address

This field stores the IP of the source of the packet.

Destination IP address

This field stores the IP of the packet’s destination.

IP Address Security and Privacy

IP addresses pose security and privacy risks, as they reveal device locations and enable tracking.

Risks

• IP Spoofing: Attackers fake IP addresses to impersonate devices.
• Tracking: Websites log public IPs, potentially linking them to user behavior.
• DDoS Attacks: Public IPs are targets for denial-of-service attacks.

Solutions

• VPNs: Mask your public IP by routing traffic through a server (e.g., NordVPN).
• Firewalls: Block unauthorized access to your IP.
• NAT: Hides private IPs behind a public IP.
• IPv6 Privacy Extensions: Randomize IPv6 addresses to reduce tracking.

How to Find Your IP Address

Finding your IP is simple. Here’s how:

On Windows

1. Open Command Prompt (Win + R, type cmd).
2. Type ipconfig and press Enter.
3. Look for “IPv4 Address” (e.g., 192.168.1.5) under your active network.

On Linux/Mac

1. Open Terminal.
2. Type ifconfig or ip addr and press Enter.
3. Find your IP under the active interface (e.g., eth0 or wlan0).

Public IP

• Visit sites like whatismyipaddress.com to see your public IP (e.g., 203.0.113.1).