Friday, 19 October 2012

Fixing things

1. The server that occasionally rebooted. I took out the memory, and put in a different memory stick. Unfortunately I put it in the wrong way round, which is almost impossible because it's keyed, and I saw blue smoke. That fried the memory stick and wrecked the motherboard. After I replaced the motherboard and memory stick, it's working fine.

2. The bicycle that had the back brakes jammed on. I replaced the brake pads, and after messing around with it for a while, I realised that the springs that return the brakes to "off" weren't working. So I took that apart, saw why, and fixed it.

3. Me. I had a couple of nosebleeds recently, including one that was about a thimbleful. So I went to soo the doctor. He didn't seem concerned, but took my blood pressure, which he said is really excellent.  No action required.

4. Bike lock. The lock I've been using for my bike fell apart. I was going to buy a replacement, but then I remembered, I've already got a really good lock. So I dug that out, checked that it worked, and I'll be using that.

5. IP addresses. My packet transit provider was originally Nildram, and I got a class C (256 IP addresses) from them. But Nildram was sold to Pipex, and Pipex was sold to ... and so on and so on, I lost count, every time I called them (about once per two years) I was talking to a different company. And now, there's two parts of Nildram belonging to two different companies. Talktalk have the ADSL part, and Daisy have the leased line part. My leased line is, therefore, now with Daisy, but somehow my IP addresses wound up with Talktalk. Duh.

So Daisy want me to change all my IP addresses, because they belong to Talktalk. And that's a terrible thing to contemplate.

I've been trying to get them to change their minds, but I doubt if that's going to be possible, despite the original assurance that the sale of Nildram wouldn't affect me, and subsequent assurances from Daisy sales people that it'll all be OK.

And I can tell you, that when my contract comes up for renewal, the fact that I will have changed all my IP addresses, means that I can very easily move away from Daisy, because what I've done once, I know I can do again. So Daisy have shot themselves in the foot there. I'll be ringing round for the best pricing, and if Daisy can't match that, they'll lose a customer.

So today, I started doing the change.

First, I found out about DNS "glue records". When a domain is doing its own DNS (like if the name server for is at, it's no use telling the registrar that the nameserver for is at because, for obvious reasons, they won't be able to find it (because to find they need to know its IP address). So you have to tell them that it's at or whatever IP address it's on. Then it's accessible.

So I'll have to change my glue records for any domain that's doing its own DNS. That's a few domains, not many.

The good news, however, is that I'm making extensive use of NAT (Network address translation). So that when you come at my firewall with a request for, it translates that to, which is where the server actually is.  The advantage of that, is that I can have as many addresses that start with 10 as I want; they aren't addressable from outside my network, they're purely local to my network. You can also use addresses that start with 10, and that won't affect me using them.

So what I wanted, was for to translate to, but also for to translate to And the firewall (a Cisco Pix, a top-of-the-line firewall) wouldn't allow two addresses to be translated to one. But after much research and anguish, I found a way to fool the pix into letting me do it; this is by making use of access-lists. I won't give you the gory details.

I've tried it, and it seems to work. So when I move to the new addresses, I can have a period in which both the new, and the old addresses both work. And you can see how that will make my life a lot easier!

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