n2n (by alaric)

n2n looks like a lovely piece of technology.

It's basically a VPN system, but quite different from existing VPN technologies. Existing VPNs work by creating a point-to-point link between two systems, usually a personal computer on an untrusted, remote, and often frequently changing network - and a router which then routes or bridges traffic (depending on the layer the VPN operates on) to other VPN clients and/or a physical private network.

The usual configuration is that there's a network with some resources on it that can't be trusted to the open Internet - insecure file sharing or network management services, for example - with an access device connected both to that network and the public Internet, such that remote computers can connect to the access device via the Internet and thus be virtually and securely connected to the private network so they can access the resources therein as if they were physically plugged into it. All over an encrypted link that they need to authenticate to set up, keeping third parties from reading or injecting traffic.

But the conventional VPN approach doesn't work so well for more complex setups. I, for example, have two private networks with various servers and workstations on, an isolated server, and two roaming laptops. It would be nice if I could set up varying levels of trusted connectivity between the three; the isolated server should really appear to be local to the first private network, which could be done with a conventional VPN, except that a permanent connection would require the isolated server to try to set the VPN up on boot and, if it goes down due to network problems or the access server on the private network rebooting, retry the connection automatically. Likewise, I'd like some level of routing between the two private networks, with a bit of packet filtering to tailor the precise trust relationship; I'd have to choose one network's router to be the VPN server and the other the client, set up another auto-reconnecting VPN, and set up routing across it. Then have the laptops also connect to a VPN server on one of the private networks, or perhaps the isolated server, to then use routing across the VPN links between the two private networks in order to reach everything they should be able to.

In practice, I'd probably pick the best connected private network to be the hub, and run a VPN server on it, and have everything else connect to that. Traffic between a laptop and the other private network would go via the hub, causing double bandwidth consumption at the hub and increasing latency. If the hub goes down, the whole network is fragmented.

Plus, mainstream VPN protocols are a pain to configure and use, as they tend to use strange protocols like GRE.

But n2n is much better than all that.

The Camping Holiday Of Despair (by alaric)

The plan was simple: borrow Sarah's parent's campervan, drive down on Friday evening to the village where our friends were being married the next day, sleep over, get up in the morning, have a nice breakfast, explore the area a bit, do the wedding, sleep over, then have Sunday to do touristy things with a few of the others who were staying over after the wedding, sleep over, and come back Monday morning.

However, it did not go to plan.

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Uniqueness Typing (by alaric)

Ever since I was a kid, I've been interested in exploring Uniqueness typing as a paradigm for mutation in a programming language.

The principle is simple: mutating operations - assignment, I/O, etc - are a pain. Both for the implementers of the language, who are limited in what optimisations can be performed when the values of things can shift around beneath them and when any given part of the program may have side effects so order of execution must be preserved, and for the programmers in the language, who have to deal with bugs and complex behaviour that just don't happen when everything is referentially transparent.

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The floor is in… (by alaric)

Well, today, the nice carpet men came and finished putting our flooring in...

...so we can now start moving furniture in, and things to go on the furniture! Hopefully we'll be back in our home soon! It's only been NINE MONTHS...

Stuck in the back of an out-of-control vehicle careening down a slope! (by alaric)

The scene: I, with my family, are in a Little Chef. Jean, bless her, has got food all over herself, so I go out to the van, in the car park, to get wet wipes.

I unlock the back, hop in, go to the box of stuff, and start rooting about for wipes. I feel a slight motion, and wonder if it's strong wind rocking the van, or if somebody bumped into it while getting into an adjacent car as I continue to root. Then I feel a bigger rocking motion, and look outside to, to my horror, see the world moving... the van's rolling backwards, with me in the cargo bay and nobody in the front!

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