Comments on: Decoding IP Addresses from phpBB2

By: Dog Cow

Dog Cow — Thu, 14 Aug 2008 19:40:10 +0000

The backward compatibility is built not into the protocol itself, but rather the machines, network hardware, and software that support it.

By: Dave Rathbun

Dave Rathbun — Thu, 14 Aug 2008 03:59:09 +0000

My assumption was that it had to be evolutionary rather than revolutionary or the entire Internet would have to be upgraded all at once. I don’t see that happening. Therefore there had to be some backward compatibility available. As to why I don’t know much, I’ve never needed to know. I provided the wiki link as a note to myself as much as anything else so I can go back out and read it further.

By: Dog Cow

Dog Cow — Thu, 14 Aug 2008 00:51:24 +0000

*puts on his arrogant face*

I can’t believe you don’t know much about IPv6. I mean, even I didn’t a few months ago, but I got a new Mac and was checking out the Ethernet settings and noticed that it had IPv6 option, so I turned it on and connected to the localhost forums with it. I also strung a cross-over cable to my Mac G3 and loaded web pages across it with IPv6. WIth my network configuration, the IP addresses are 127.0.0.1 when not connected to a network, and then they are only assigned when connected (to avoid conflicts!). I don’t know off-hand what the IPv6 address for my Mac is, since I’m not at it right now, though.

Anyway, if your machine has IPv6 ability, I recommend enabling it and seeing the results.

IPv6 is completely new. It has no relation to IPv4, so it’s not “added-on” or anything. I personally can’t wait until most of the entire world switches to v6. It has so many benefits which aren’t technical, such as the fact that since there are more addresses available, logically that would follow that buying an IPv6 address should cost less money.

By: Dave Rathbun

Dave Rathbun — Wed, 13 Aug 2008 21:49:45 +0000

Micheal, so what does a real IP address look like then? Are the leading values the “new” values? It would seem so, if the 0001 comes at the end. But it also seems that they haven’t just added a couple of octets… they’ve changed the entire structure.

Hm. More research is required, it seems.

Wiki on IPv6

http://en.wikipedia.org/wiki/Ipv6

By: Micheal

Micheal — Wed, 13 Aug 2008 20:44:34 +0000

IPv6 is in the following format: 0000:0000:0000:0000:0000:0000:0000:0001. This is the same as the familiar 127.0.0.1. That’s why on phpBB.com, you see NeoThermic and me with ::1, which is the shorthand for 0000:0000:0000:0000:0000:0000:0000:0001, or 127.0.0.1. It is all rather confusing, I know. I still don’t understand it all.

By: Dave Rathbun

Dave Rathbun — Wed, 13 Aug 2008 18:21:57 +0000

What is the format for IPv6? I assumed (perhaps a bad thing to do) that it was xxx.xxx.xxx.xxx.xxx.xxx instead of just xxx.xxx.xxx.xxx for IPv4. If that’s the case, a very simple change to extend the character field size to handle the extra two octets would have worked fine. There’s no need to drop the encoding strategy.

For example, try to find every IP address that matches the wildcard 127.XXX.XXX.1 with an encoded value and it’s quite easy, you match 7f____01 and you’re done. With unencoded data you have to allow for strings of different lengths.

I should probably do more research on exactly what IPv6 looks like, as it might change my opinion. But for now, I’ll stick with the idea that encoding would be better for pattern matching and any process (like banning) that requires that process would be more efficient.

By: Dog Cow

Dog Cow — Wed, 13 Aug 2008 16:43:58 +0000

I know why. Try accessing a phpBB 2 board with an IPv6 address (which I have done with my own Mac on localhost).
On v2, your IP will register as 0.0.0.0. On v3, it will register as a normal v6 address.

So, they had to support IPv4 and v6 and decided not to encode.