ipv4

10 Articles

The IPV4 We Didn’t Get

March 16, 2026 by 24 Comments

If you have ever read science fiction, you’ve probably seen “alternate history” stories. You know, where Europeans didn’t discover the New World until the 19th century, or the ancient Egyptians stumbled upon electricity. Maybe those things happened in an alternate universe. [BillPG] has an alternate history tale for us that imagines IPv6 was shot down and a protocol called IPv4x became prominent instead.

The key idea is that in 1993, the IP-Next-Generation working group could have decided that any solution that would break the existing network wouldn’t work. There is precedent. Stereo records play on mono players and vice versa. Color TV signals play on black and white sets just as well as black and white signals play on color TVs. It would have made perfect sense.

How could this be? The idea was to make everyone who “owns” an IPv4 address the stewards of a 96-bit sub-address block. IPv4x-aware equipment extracts the entire 128-bit address. IPv4-only equipment routes the packet to the controlling IPv4 address. Wasteful? Sure. Most people don’t need 79 octillion addresses. But if everyone has that many, then why not?

The fictional timeline has DNS and DHCP, along with dial-up stacks, changing to accommodate the new addresses. Again, you had to assume some parts of the network were still IPv4-only. DNS would return both addresses, and it was up to you to pick the IPv4x address if you understood it.

Your ISP would probably not offer you the entire extra space. A regional router could handle all traffic for your neighborhood and then direct it to your specific 128-bit address or your pool of addresses, if you have multiple devices. No need for NAT to hide your devices, nor strange router configurations to punch traffic through.

Of course, back in the real world, we have two incompatible systems: IPv4 and IPv6. IPv6 adoption has been slow and painful. We wondered why [BillPG] wrote about this future that never was. Turns out, he’s proposed a gateway that IPv6 hosts can provide to allow access from IPv4-only networks. Pretty sneaky, but we can admire it. If reading all this makes you wonder what happened to IPv5, we wondered that, too.

It’s 2025, And We Still Need IPv4! What Happens When We Lose It?

July 3, 2025 by 79 Comments

Some time last year, a weird thing happened in the hackerspace where this is being written. The Internet was up, and was blisteringly fast as always, but only a few websites worked. What was up? Fortunately with more than one high-end networking specialist on hand it was quickly established that we had a problem with our gateway’s handling of IPv4 addresses, and normal service was restored. But what happens if you’re not a hackerspace with access to the dodgy piece of infrastructure and you’re left with only IPv6? [James McMurray] had this happen, and has written up how he fixed it.

His answer came in using a Wireguard tunnel to his VPS, and NAT mapping the IPv4 space into a section of IPv6 space. The write-up goes into extensive detail on the process should you need to follow his example, but for us there’s perhaps more interest in why here in 2025, the loss of IPv4 is still something that comes with the loss of half the Internet. As of this writing, that even includes Hackaday itself. If we had the magic means to talk to ourselves from a couple of decades ago our younger selves would probably be shocked by this.

Perhaps the answer lies in the inescapable conclusion that IPv6 answers an address space problem of concern to many in technical spaces, it neither solves anything of concern to most internet users, nor is worth the switch for so much infrastructure when mitigations such as NAT make the IPv4 address space problem less of a problem. Will we ever entirely lose IP4? We’d appreciate your views in the comments. For readers anxious for more it’s something we looked at last year.

IPV4, IPV6… Hey! What Happened To IPV5?

March 9, 2025 by 37 Comments

If you’ve ever been configuring a router or other network device and noticed that you can set up IPv4 and IPv6, you might have wondered what happened to IPv5. Well, thanks to [Navek], you don’t have to wonder anymore. Just watch the video below.

We will warn you of two things. First, the video takes a long time to get around to what IPv5 was. In addition, if you keep reading, there will be spoilers.

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Front view of blue bicycle with Raspberry Pi webserver

Pedaling Your Mobile Web Server Across The Globe

December 8, 2024 by 11 Comments

We tinkerers often have ideas we know are crazy, and we make them up in the most bizarre places, too. For example, just imagine hosting a website while pedaling across the world—who would (not) want that? Meet [Jelle Reith], a tinkerer on an epic cycling adventure, whose bicycle doubles as a mobile web server. [Jelle]’s project, jelle.bike, will from the 6th of December on showcase what he’s seeing in real time, powered by ingenuity and his hub dynamo. If you read this far, you’ll probably guess: this hack is done by a Dutchman. You couldn’t be more right.

At the heart of [Jelle]’s setup is a Raspberry Pi 4 in a watertight enclosure. The tiny powerhouse runs off energy generated by a Forumslader V3, a clever AC-to-DC converter optimized for bike dynamos. The Pi gets internet access via [Jelle]’s phone hotspot, but hosting a site over cellular networks isn’t as simple as it sounds. With no static IP available, [Jelle] routes web traffic through a VPS using an SSH tunnel. This crafty solution—expanded upon by Jeff Geerling—ensures seamless access to the site, even overcoming IPv6 quirks.

The system’s efficiency and modularity exemplify maker spirit: harnessing everyday tools to achieve the extraordinary. For more details, including a parts list and schematics, check out [Jelle]’s Hackaday.io project page.

Embrace IPv6 Before Its Too Late?

June 8, 2024 by 96 Comments

Many hackers have familiar sayings in their heads, such as “If it ain’t broke, don’t fix it” and KISS (Keep it simple, stupid). Those of us who have been in the field for some time have habits that are hard to break. When it comes to personal networks, simplicity is key, and the idea of transitioning from IPv4 to IPv6 addresses seems crazy. However, with the increasing number of ‘smart’ devices, streaming media gadgets, and personal phones, finding IPv4 space for our IoT experiments is becoming difficult. Is it time to consider embracing IPv6?

The linked GitHub Gist by [timothyham] summarizes the essential concepts for home network admins to understand before making changes. The first major point is that IPv6 has a vastly larger address space than IPv4, eliminating the need to find spare IPv4 addresses. IPv6 assigns multiple addresses to the same interface. The 128-bit addresses are split into a 64-bit prefix assigned by your ISP and a 64-bit interface identifier. Using SLAAC (Stateless Address Autoconfiguration), clients can manage their own addresses. You don’t have to use SLAAC, but it will make life easier. The suffix typically remains static, allowing integration with a local DNS server.

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FLOSS Weekly Episode 770: 10% More Internet

February 14, 2024 by 7 Comments

This week, Jonathan Bennett and Doc Searls talk with David Taht about the state of the Internet and, specifically, IPv4 exhaustion. We’re running out of IPv4 addresses! But we’ve been running out for something like ten years now. What gives? And why are nearly 20% of the world’s IPv4 addresses sitting unused? David has a hack that would give the world 10% more Internet, but Amazon might have something to say about it.

There’s even more, like Kessler Syndrome, some musing on what the Interplanetary Internet will look like, the worth of real paper books, and a long-term bet for some IPv4 addresses to come to fruition in 2038.

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Where Exactly Did That Network Packet Come From?

May 26, 2023 by 11 Comments

Have you ever noticed that some websites can figure out, at least roughly, where you are? Sometimes they use it to find you a closer content provider. Or they might block you from seeing certain things while offering you other things specific to your location. This is possible because there are databases that map IPs to locations. [Mark Litwintschik] looks at using those databases from an API or downloading them into your own database. He also shows some very large database queries, which is interesting, too. He uses IPInfo, although there are other providers. Some only provide a limited number of lookups, but there are plenty of free tiers for low-volume usage.

The database changes every day. Of course, each provider has a different way of getting data, and so there are differences. [Mark] compares the IPInfo dataset against MaxMind’s also free database. That involved comparing over 3 billion records! Actually, the 3 billion are the number of IPs that matched up in both databases. There were an additional 118 million that didn’t match and 34 million that were not in the MaxMind database.

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