Sunday, February 21, 2016

Retrospective: IPv6 Utility

When I first started my journey to learn IPv6, I could not get native IPv6 at home from my residential ISP. Undeterred, I went to Hurricane Electric; HE offers both an IPv6 certification program that's a great place to start to learning how IPv6 works, and free IPv6 tunnels. I still recommend their certification as a first step to learn IPv6. (If you can't get native IPv6, you should start by asking your ISP for their timeline to offer access to the entire Internet before getting a tunnel. I would like to think that the excuse "no one is asking for IPv6" is no longer used, but the only way to be sure of that is to ask for it.)

I had my IPv6 tunnel, and I made sure I knew the security stance of anything on my home network with an IPv6 address, but I didn't use it much when I wasn't at home. During this time, I've gotten more confident with my ability to secure my home network as I intend.

At the same time, I've started to use my home network as a testbed for ideas; it's my "proof of concept lab" before I try it at scale at work.

As my ideas have gotten more complicated, I realized I needed a better system for my notes. At work, we use PmWiki, so I decided to use it for my project notes.

I created a new VM for PmWiki, and started to install it. However, I couldn't download PmWiki! Eeek! A quick check showed me that only had an IPv4 address, and for some reason this VM didn't get a DHCPv4 lease (behind NAT, of course). I really wanted to finish my task, so I used a host that I knew was properly dual-stacked to download, then transferred the tarball from there. I did have to use an intermediate host for its dual-stack visibility into both IPv4 and IPv6 networks, but it didn't take much longer to do that two-step download, and I quickly had PmWiki installed, configured, and running as I wanted.

In fact, it was running so well that I never made time to go back to troubleshoot why this VM host had not gotten an IPv4 address. I could use it when I was at home because I now have native IPv6 (and NAT'd IPv4) at home. I could use it at work because I have dual-stack (native IPv6 and IPv4) there. I was curious to know why it didn't get an IPv4 DHCP lease as expected, but I don't always want to troubleshoot networks when I get home ... that's what I do at work! Several rounds of patches and reboots later, many months later, I noticed that this VM had picked up a DHCP lease, so whatever was broken before wasn't badly broken. My point, though, is not that I was a lazy troubleshooter at home.

My point is that I barely noticed the lack of IPv4 on one of my hosts at home; all I needed to do everything I wanted to do was IPv6. Notably, the reverse would not have been true! Without an IPv6 address on this host at home, I would not have been able to access it while at work without doing a fair amount of port mapping on my home router. With a global IPv6 address, I was able to firewall it to talk only to my home network and to my work network. IPv6 made this easy; I did not miss IPv4 enough to bother figuring out why it didn't work when this VM was created. I would have freaked out without IPv6, and I didn't care about IPv4.

My, how far IPv6 has come! It used to be shiny, and now it's the thing that makes my network easier to use.

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