May 22, 2007

Thought I’d mention a great utility I discovered the other day. I was looking for a way I could attach a laptop bag to my bike, a Dahon Jetstream P8. This is a great folding bike but because it has front and rear suspension (tried cycling through Cambridge city centre recently? Cobblestones look nice but shake Bromptons and their riders to bits) I haven’t been able to find a suitable rear (or front) rack/pannier. Anyway in my travels through Google I came across a conversation trail which started with the pros and cons of carrying around a USB memory stick instead of a heavy laptop, and moved onto the service provided by www.logmein.com.

Remote desktop services are now built into Windows, and tools like VNC and Netmeeting have been around for years, but what this makes this nice is that Logmein provide a hosted service so that I can run up their application on my laptop at work and this connects to their central server. When I get home I boot up my desktop (assuming Son #2 is not playing Fifa 2006) and it connects via the Logmein server to my laptop and voila I get to remotely control my laptop.

I currently use two main products at work. First is Enterprise Architect. This is a per-seat licenced tool and Logmein lets me remotely work with this tool. The second is a local installation of MediaWiki. Now I can access this by using a remote instance of Firefox but of course I want to do better than that!

On the LogMeIn site I found a link labelled ‘Labs’ – and through that I came across their Hamachi service. Hamachi provides a flexible peer to peer network bridge between a cooperating set of user machines. It creates a new network interface on each machine on which it is installed and lets users create ad-hoc network communities that behave like a local LAN. The immediate benefit is that it lets game players form lan based multiplayer games without having to connect to a third party server (including FIFA 2006, but I haven’t told him yet…). The real benefit is that I can install hamachi on my Ubuntu Linux desktop at work, bring up a local instance of Squid as a Web proxy and thus gain access to the intranet instance of MediaWiki.

Now I don’t really want to route all my web traffic through Hamachi, then to work and out through Squid so I needed to find a way to selectively route only requests to my wiki. Firefox lets you configure a Proxy but the way that works is that you can specify sites not to proxy, but not the other way round. The answer is to create a small file called ‘Proxy.PAC’ and implement a small Javascript method. Here’s mine (with the relevant names and addresses changed to protect the guilty)

function FindProxyForURL(url, host){
 var proxy="PROXY 5.16x.xxx.xxx:8080";
 if (shExpMatch(url,"*.company.co.uk:*/*"))              {return proxy;}
 return "DIRECT";

So now I can access my company Wiki at home. The only disadvantage is that I can’t boot up the laptop while I’m on the train and work offline but given the level of overcrowding on my train at present I don’t always get the opportunity to work in this way.


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