SOCKS vs NAT (by alaric)

The standard solution these days to the problem of a large internal network of client machines that need Internet access is to stock them behind a NAT, with a single external IP from which connections can originate.

However, before NAT was popular, I remember setting up SOCKS proxies, which did more or less the same thing.

The downside was that not all applications supported SOCKS, and annoyingly there generally wasn't an easy way of telling the whole machine to use SOCKS; each application had to be configured manually, while NAT works by providing the illusion of real Internet access.

The upside, however, is that SOCKS doesn't work by fooling anyone. The application knows that the IP address it gets from the local stack is not necessarily global, and can ask the SOCKS server what the global address is. And the application can ask for a listening socket, making peer to peer file transfers and the like work properly.

Perhaps rather than using NAT for more and more, we ought to be putting support for SOCKS right into the IP stacks of operating systems, so applications using the standard TCP/IP APIs work with SOCKS right out of the box, and specifying a DHCP option so a DHCP server can nominate a SOCKS server to a client machine?

Then we wouldn't have all this pain with peer-to-peer file transfers...

Local community (by alaric)

The village we live near, Cranham, has a particularly strong community, which we are slowly working our way into (limited somewhat by the fact that we have very little free time right now).

So today we went along to a Christmas carol singing event at the village hall. Our very own GP was there ringing handbells, and afterwards we chatted to some of our new neighbours; including a lady who (like me) grew up only seeing from one eye (and thus had a very similar experience of problems with depth perception), and another lady whose first job had been programming in assembly language and COBOL in the 1960s (on PROPER computers with punched cards).

Mmmm, people with things in common with me... and they're all so friendly. It's a far cry from life in London, or indeed in Luton where I grew up.

This is going to be a lovely place for Jean to grow up! I really need to start getting involved more in local life, though - I've been idly discussing with a few people that the school's nice optical fibre Internet connection could be share with nearby residents (who can't get good ADSL due to our distance from the exchange) with a wireless bridge... and there are myriad societies to join...

Old-school brazing (by alaric)

Yesterday, my mate Seth was trying to fix his car exhaust pipe. It had a bit that was made out of corrugated metal tubing, presumably to allow one end of the pipe to vibrate with the engine while the other is fixed.

Anyway, in the way of these things, with all the vibration and heat, it had broken off at one end, leaving the fragmented end of the corrugated thin metal tubing; now without the straight bit of tubing that would nicely clamp around the next bit of pipe.

So we decided to braze it - and due to the scale of the job and the small scale of my supplies of silver solder, to old-school braze it with real brass. After a lot of angle grinder work cleaning the corrugated tube end up and preparing an extension tube made from a tin can (ground down to reveal the steel sheeting within), we smeared a load of flux paste on, heated it up to a orange-ish red, squirted MORE flux paste on, and applied some brass rod I had lying about. Read more »

Generator trials (by alaric)

Yesterday, my friend Mike (who is interested in generators) was around, so we tested the generator out with the cable I made.

It could run the computers, or the fridges and freezers, without straining; I couldn't try running everything at once since I don't have the spur in my cable yet to reach both bits of the house.

We tried running the kettle on it, since it's a 2kW kettle and a 2.1kW generator, and when the kettle was switched on you could hear the generator rev up to deal with the load, then when the kettle clicked off, the generator settled down again.

I wonder how the generator actually outputs AC - the revving up and down would imply that it's not just a synchronous generator. Also, when I hooked it up to an oscilloscope, it showed some kind of spiky noise at a few hundred Hz (nicely synchronised to the 50Hz sine wave) - so perhaps it's a DC generator running an inverter with voltage and frequency regulation?

The computers ran fine with the noise - but the UPS was suspicious of it and thought the incoming frequency was fluctuating between 50Hz and 80-90Hz, so kept switching to battery and back again. In the long run this would probably run the battery out, so I may have to build some kind of low-pass filter (at scary mains voltages and high currents!), just to stop it panicking.

Talking ’bout my generation (by alaric)

Since, as I mentioned before, the generator has 16A IEC 60309 weatherproof power outlets:

...I had to order special bits to make a nice lead for it. Well, they arrived today (along with a 20 litre petrol can), so I've made my nice lead:

Doesn't that look like it was bought in a shop rather than home-made? Nice arctic-grade PVC cable, since it'll need to run outside (we're not running the genset indoors!)

Well, that's the prototype of it. I have the same length of cable again plus a second set of sockets. I need to get a junction box to run the second set off, since we will need backup power on both floors of the house.

Since it took forever to get the nice white grommet on the cable where it goes into the twin socket, rather than redo it, I'll just cut the wire a metre back from the sockets to put the junction box on, making this just a little spur in a long cable.

And if there are any problems with power factors, I'll put appropriate reactive components in the junction box (plus test points so I can use my dual-trace scope to get voltage and current traces), too.