What is a public IP address?

• Public IP addresses are unique identifiers assigned by ISPs to devices for internet communication, enabling global connectivity and data exchange
• They are essential for hosting websites, supporting remote access, and facilitating IoT, with both dynamic and static options available for diverse use cases

The internet is the most important topic that has surrounded us from many angles in this increasingly digital world and the context of computer networks. The internet is connected to a number of our everyday electronic devices, including computers, tablets, smartwatches, and smartphones.

For any of these devices to interact with the wide variety of devices across the world, they each must have a unique network identity. So this identifier, which is assigned to each device, is known as an internet protocol, or what we call an IP address.

IP addresses are divided into two sub-parts known as private IP address and public IP address. A private IP address is a static IP address that cannot be changed. This article covers in detail the second part which is the public IP address.

What is a public IP address?

An IP address is a unique numerical identifier assigned to every device or network that connects to the internet. Dr. Leonard Kleinrock, a pioneer in packet-switching and a key figure in the development of the internet, defines an IP address as “a structured numerical label that allows computers and devices to identify themselves and exchange information on a global scale”. It acts as the virtual address of a device, enabling communication between devices across the internet.

Public IP addresses, as the name suggests, are accessible over the internet. Paul Mockapetris, the inventor of the Domain Name System (DNS), explains public IPs as “essential digital identifiers that enable direct communication between devices and the internet, forming the basis of web hosting and data exchange”. Unlike private IP addresses, which are confined to local networks, public IPs allow devices to interact globally. Your internet service provider (ISP) assigns a public IP address to your router, facilitating connectivity with other devices and servers worldwide.

Also read: How did the internet start?
Also read: Interview with Lu Heng: The man who wants to decentralise IP addresses and save the internet

Key features of public IP addresses

Internet accessibility

Public IPs make it possible for devices to send and receive data over the internet. As Vinton Cerf, widely regarded as one of the “fathers of the internet,” once stated, “The ability to address devices uniquely is the backbone of our internet’s open connectivity and its global success.” This underscores the pivotal role of public IPs in sustaining the internet’s global reach and interoperability.

Cerf’s insight highlights the foundational role public IP addresses play in ensuring that devices, irrespective of location, can communicate seamlessly. Without such unique identifiers, global networks would fragment, drastically reducing the efficiency of internet communication.

Website hosting

Public IPs are essential for hosting websites or applications that require global access. Tim Berners-Lee, the inventor of the World Wide Web, noted, “A website’s visibility hinges on its ability to connect users globally, and public IP addresses form the cornerstone of this reach”.

Berners-Lee emphasizes that public IPs are indispensable for ensuring that websites and applications are accessible worldwide. Without them, services reliant on broad connectivity, such as e-commerce platforms or global cloud applications, would face severe limitations.

Dynamic and Static Assignments

Public IPs can be assigned dynamically (temporary) or statically (permanent) based on specific needs. Dr. Radia Perlman, a networking pioneer and the creator of the Spanning Tree Protocol, stated, “Dynamic IP allocation optimizes resource use, but static IPs are crucial for stability in business applications requiring consistent connectivity”.

Perlman’s observation reflects the dual nature of public IP assignments, highlighting the efficiency of dynamic IPs for casual users and the necessity of static IPs for businesses and services with specialized connectivity needs. Her perspective offers a balanced view of the trade-offs between flexibility and reliability in IP management.

A website’s visibility hinges on its ability to connect users globally, and public IP addresses form the cornerstone of this reach.

Tim Berners-Lee, the inventor of the World Wide Web

How public IP addresses work

Public IP addresses serve as gateways between individual devices and the broader internet. When your home or business connects to the internet, your ISP assigns your router a public IP address. All devices on your network then share this public IP for external communication.

For instance, when you visit a website, your device sends a request to the site’s server using your public IP address. The server then sends data back to your address, ensuring seamless communication. As Kevin Mitnick, a renowned cybersecurity expert, explained, “Your public IP is essentially your home address on the internet. It’s how other computers or services know where to send the information you’ve requested.”

Dynamic Host Configuration Protocol (DHCP)

The Dynamic Host Configuration Protocol (DHCP) is commonly used by ISPs to assign public IP addresses dynamically. This means the IP address can change periodically, optimizing the pool of available addresses for efficient use. Mark Nottingham, a thought leader in internet architecture and HTTP standards, highlighted the efficiency of this system: “DHCP ensures the internet can cater to millions of devices, enabling smooth connectivity by dynamically allocating IP addresses based on demand.”

Static public IPs

Some organizations prefer static public IPs for consistent connectivity. These are ideal for hosting servers, websites, and applications that demand stability. Dr. Henning Schulzrinne, co-developer of the RTP (Real-time Transport Protocol), emphasized their importance: “For applications requiring reliability, such as VoIP or hosting services, static public IPs provide a stable and consistent identity essential for uninterrupted operation.”

Your public IP is essentially your home address on the internet. It’s how other computers or services know where to send the information you’ve requested.

Kevin Mitnick, a renowned cybersecurity expert

Public vs. Private IP addresses

Private IP addresses are used within local networks, such as homes or offices, to identify devices without being directly accessible over the internet. For example, your smartphone, laptop, and smart TV might all have private IPs within your home network, but they share a single public IP for external communication.

Key differences

Types of public IP addresses

Public IP addresses are classified into two main categories: dynamic and static. Each type serves different purposes and has distinct advantages and disadvantages.

Dynamic public IP addresses

Dynamic IP addresses are temporarily assigned by ISPs from a pool of available addresses. They are cost-effective and suitable for general users, but their changing nature may pose challenges for specific use cases like hosting.

Kevin Mitnick noted that, “Dynamic IPs offer a layer of unpredictability, which can be beneficial for everyday users to reduce direct cyber threats, but they fall short when consistency is required.” This transient nature makes them ideal for casual browsing but less effective for permanent services.

Advantages:

• Efficient use of IP pools.
• Lower risk of being targeted by hackers, as the IP frequently changes.

Disadvantages:

• Interruptions for services requiring consistent IPs.
• May complicate remote access configurations.

Dynamic IPs offer a layer of unpredictability, which can be beneficial for everyday users to reduce direct cyber threats, but they fall short when consistency is required.

Kevin Mitnick, a renowned cybersecurity expert

Static public IP addresses

Static IP addresses remain fixed over time, making them reliable for businesses or individuals who host websites, operate servers, or need a stable address for remote access.

Paul Mockapetris, the inventor of DNS, emphasized, “Static IPs are the backbone of critical internet services. They provide the stability and predictability that businesses need for uninterrupted operations.” However, this consistency comes with increased risk.

Additionally, Dr. Henning Schulzrinne observed, “Static IPs are essential for applications like VoIP and enterprise VPNs, ensuring reliability in communication and remote work environments.”

Advantages:

• Reliable for hosting and remote access.
• Easier to configure services like VPNs.

Disadvantages:

• Higher cost.
• Greater exposure to cyber threats due to static nature.

Elaborating further, cybersecurity expert Bruce Schneier remarked, “The predictability of static IPs makes them more susceptible to targeted attacks, emphasizing the importance of additional security layers for these addresses.” This underscores the trade-off between reliability and vulnerability in choosing static IPs.

Static IPs are essential for applications like VoIP and enterprise VPNs, ensuring reliability in communication and remote work environments.

Henning Schulzrinne, co-developer of VoIP protocols

How to find your public IP address

Finding your public IP address is simple:

1. Search engines: Typing “What is my IP?” in a search engine will display your public IP.
2. Router settings: Log into your router’s admin panel for detailed network information.
3. Command prompt or terminal: On Windows, type ipconfig in Command Prompt. On macOS or Linux, use curl ifconfig.me in Terminal.

Uses of public IP addresses

Public IP addresses are essential for a variety of internet-related activities:

1. Hosting websites:
   Public IPs enable hosting websites or applications accessible to global users. They serve as the unique identifier for web servers, ensuring seamless communication between users and the hosted content. Tim Berners-Lee, the inventor of the World Wide Web, explained, “Without public IP addresses, the internet as we know it wouldn’t exist—they are the building blocks that allow websites to be universally accessible.”
2. Remote access:
   Businesses use static public IPs to provide remote access to their servers and systems. This setup ensures secure and uninterrupted connectivity. Dr. Vinton Cerf, often called one of the “fathers of the internet,” emphasized, “Remote access relies on static IPs for reliability and stability, making them indispensable for enterprise solutions.”
3. Gaming:
   Public IPs facilitate multiplayer online gaming, allowing players to connect globally. They enable gaming consoles and PCs to act as servers, hosting matches and ensuring smooth gameplay across regions.
4. IoT connectivity:
   Internet of Things (IoT) devices, such as smart home systems, often require public IPs for remote monitoring and control. These addresses help IoT devices communicate with apps and users securely.

Also read: Which organisation is responsible for allocating public IP addresses?

Security concerns with public IP addresses

While public IP addresses enable connectivity, they also expose devices to potential risks.

Common threats:

• Hacking: Static IPs are more vulnerable as attackers can target them consistently.
• DDoS attacks: Cybercriminals may overload a public IP with traffic, disrupting services.
• Data snooping: Public IPs can be exploited to track online activities.

How to protect your public IP:

1. Use firewalls: Implement network firewalls to monitor and control traffic.
2. VPNs (Virtual Private Networks): Mask your public IP address to maintain anonymity.
3. Regular updates: Keep devices and routers updated to prevent vulnerabilities.

IPv4 vs. IPv6 public IP addresses

The internet primarily uses two IP address formats: IPv4 and IPv6.

IPv4

IPv4 addresses are 32-bit numbers, offering approximately 4.3 billion unique addresses. Due to rapid internet expansion, IPv4 addresses are nearly exhausted.

Example: 203.0.113.1

IPv6

IPv6 was introduced to address IPv4 limitations. It uses a 128-bit format, providing an almost infinite number of addresses. IPv6 also offers improved security and efficiency.

Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Future of public IP addresses

Public IP addresses play an integral role in our increasingly digital world, acting as the unique identifiers that allow devices to communicate across the internet. As the backbone of internet connectivity, these addresses enable not only basic functions like web browsing and email, but also more complex systems like cloud computing, IoT devices, and online gaming.

The shift from IPv4 to IPv6 is a critical milestone in addressing the limitations of the current internet infrastructure. IPv4, with its limited address pool, has already reached a point of exhaustion, making the transition to IPv6 essential for the future. IPv6’s significantly larger address space, along with built-in security features, makes it the foundation for a more scalable, secure, and efficient internet.

Looking to the future, public IP addresses will continue to be central to global internet operations. The ongoing development of IPv6 will ensure that the world remains connected in ways previously unimaginable. Yet, as the number of connected devices increases, there will be an even greater focus on network security and efficient IP address management to avoid congestion and security breaches.

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