Potty Page

January 16, 2006

Last week the network broke...

...as some of my readers will know (especailly those who were trying to print out coursework 15 minutes before the deadline), the ElecEng network went all broken last week - so printers and the like didn't work.

Once again I saved the day (and not actually knowing that the printers were all broken) because I noticed that there were two DHCP servers trying to give my laptop an IP address instead of the one it should have been. To make it worse, the rogue was handing out private 192.168.1.x addresses, and telling everyone that it was also the DNS server - the server which maps names like www.bloged.co.uk to numbers, like It was also telling everyone that it was the gateway - the box which will let me off the local network onto something much bigger (the Internet).

This somewhat messed things up - you couldn't find out where Google was for instance, because the rogue DNS server had no idea where it was, and even if you could find out it's address all the machines were given addresses the university routers didn't know what to do with... not that you'd ever reach the university routers, 'cause the rogue one wanted to do it all!


Upon finding the two DHCP servers on the network I went to tell the IT guy, 'cause I was sure he'd be looking into it - and knew that he'd never suspect another DHCP server giving out addresses (even though it probably happens about once a year when someone does something stupid...). I even went armed with the hardware address of the evil box, to aid finding which network point it was plugged into...

Sure enough, he was wondering why the printers weren't working...

I went back to my lab and within minutes the network started to, erm, work again... wikky...

I decided to go back up to him to ask whereabouts the bad box was, hoping that it wasn't someone in our research group, 'cause we take our usage of the network very seriously. Luckily, it wasn't :-)

It was (of course)... the bloody computer think-they-know-it-alls! They'd plugged the local side of a wireless broadband router into the network (effectively turning it into an access point) without turning off the built-in DHCP server... doh!

It's kind of worrying how easy it is to grind all work in the building to a halt!

Posted by Ed at January 16, 2006 11:00 AM | Ramble |