Wednesday, June 25, 2008

Unintended consequences

Sybase started using some new VPN software recently. It has a feature that on first blush seems like a good idea, but turns out not to be. I bring my laptop home from work every night, and one of the first things I do when I turn it on is to fire up the VPN. When I leave for work in the morning, I put the computer on standby, since it's much faster starting up when I get to work than hibernating or actually powering down. The VPN feature I'm talking about is the ability for the VPN to automatically reconnect after the network has dropped and reconnected. So I connect the VPN at home, then put the machine in standby, then bring it back up again at work. When I get to the office, the VPN can reconnect, without requiring the password. Perhaps you see where this is going.

I was in the office today and at one point I was copying a 2½ MB file to my machine from the network. I'm on a gigabit switch, so copying 2½ MB should be almost instant, right? No, it took 5-10 seconds each time I did it. I didn't do any real investigation, but I certainly wondered why it was so dog-slow. (Aside: where did the phrase "dog-slow" come from? Dogs are generally pretty fast.) It wasn't until I was just about to leave for the day that I noticed the VPN icon in the system tray. When I arrived at work this morning, the VPN had automatically reconnected, and all of my network access all day was done through the VPN. I shut it down and tried the same file copy again — lightning-fast (Aside: that one does make sense).

The weird thing is that I do this every day, and I've only noticed this happening a couple of times. This the first time it's happened and I didn't notice within 15 minutes and shut the VPN down.

The old VPN software would drop the VPN if the network went down, and you'd have to manually reconnect it. If I rebooted my router at home, for example, this would happen. The new software has this automatic reconnection without requiring another password, which is good, but does it without notifying the user, which is not. Another example of the Law of Unintended Consequences.

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