Recently I helped troubleshoot a networking issue with a 1Gbps link that was being fully saturated. In the end we configured a mirror port and dumped the traffic to analyse it. We ended up with >1000, 100MB files covering a half hour window. I was not sure what to do with such a quantity of data ~100GB and in the end we looked at a few caps and found the issue. However I could not help but feel that because most of the caps only covered a few seconds that I was not really looking at the full picture.
Ever used a laptop with a wireless and a copper network interface? Practically every laptop has both, so chances are you have. Have you ever wondered what happens if you plug in with copper, turn wireless on and have both interfaces configured with an IP address? I decided to do this and have a quick look at the routing table to see what goes on.
While waiting to be connected to my new ISP I was forced to use a 3G dongle for my main Internet connection. Yikes you say! Well it’s not entirely crap, I get about 2M and ssh is mostly usable. It’s like having a cable modem in 2000. As a side note giffgaff make this sort of thing really quite easy (and cheap). Anyway while browsing I noticed the usual crap low res images that appear when surfing on mobile phones, so I decided to do some investigation into what was going on. It turns out to just be fairly straightforward, all web traffic is just transparently proxied. So all that happens is a simple JavaScript injection.
So you have a mobile broadband dongle and you want to use it on Linux, one option is to just plug it in and from Gnome 3 it just works and can be set-up instantly with NetworkManager. However I require something more permanent, something that will start at boot, be less interactive and stay up. There is a lot of misinformation out there about how to do this with various programs and scripts to copy and paste. Lots of wvdial configurations and lots of poking about in /etc/ppp creating and modifying files etc.
TL;DR - Buy Super Unleaded petrol! (or don’t)
Whenever I buy coffee I usually get a small or a medium. Up to now I’ve always seemed to enjoy the small ones more. I’ve always assumed it was because a medium was too much of a good thing, which has led me to hardly ever get a large.
I use nagios to monitor servers. It’s great. I just thought I would share a quick snippet that I just put in my vimrc. It sorts the servers listed in host_name lines so they are in alphabetical order. Put the following in your vimrc, move your cursor over a host_name line and hit F2 and it will sort the server list.
Petrol prices are always on the rise. I decided to do some analysis on some raw data comparing the price of Brent crude oil and the price of petrol. The details of the analysis are on my site. I found out that there is a direct correlation between the price of Brent crude oil and the price of petrol at the pump excluding duty and VAT.
A colleague asked me how much bandwidth Spotify uses. I basically had no idea. I want to run Spotify on my mobile at some point, so it got me thinking. I decided to do some basic analysis. I ran the client behind a http proxy for a day or so and ran a tcpdump at the same time with a filter to capture all the traffic to the proxy. The dump ran from 19/10/2010 11:46 to 20/10/2010 17:19 and produced a 362M capture file. For the most part I was not playing any music, then for the last few hours I played music I had not played before.
This year seems to have flown by so it’s resolutions time again. I’ve done quite well; I managed to stay relatively healthy and read loads of books but I failed completely to keep up to date with LWN.
On Sunday (03/10/2010) my laptop had a bad crash. The screen went blank; I could still see the cursor and move it around, but could do nothing else. I could not even log in on a virtual console. After I typed the user name it came straight back with a login prompt again. I rebooted, grub loaded, Linux ran, the initramfs loaded and started and then it moaned about not being able to mount the root filesystem and dropped me to a prompt.
This is a quick guide on how to configure an ODBC connection from windows to a Symantec OpsCenter Server. OpsCenter is a Symantec product that integrates various backup products including Netbackup to generate various reports and warnings about how the systems are performing. It used to be a purchasable option with NetBackup 6, however since the release of NetBackup 7 a cut down version is bundled in. It works quite well and can generate pretty reports in various forms and do various things to them. However it’s not very customisable. OpsCenter actually uses SQL Anywhere RDBMS as a back end for all the data. Thus if ODBC is configured anything can query the very same data and produce reports. I’m going to use crystal reports to generate many pretty pie charts.
OpsCenter is a Symantec product that makes reports for various backup products including Symantec NetBackup. I recently decided that I wanted to improve the reporting of our backups so looked into playing with OpsCenter. It turns out that it’s not actually that configurable, which is a shame as it’s mostly quite good.
I use Nagios for monitoring. Up to recently I used a regular modem to send sms text messages to various people when systems are going wrong. The way this works is by using smsclient which dials up to a TAP server. [TAP] (http://en.wikipedia.org/wiki/Telelocator_Alphanumeric_Protocol) is a fairly archaic way of sending messages. It’s been fairly reliable however it has two major drawbacks, sending takes a long time and it’s limited to 160 characters. As far as I can tell it will not do long text messages, which are really just multiple short message combined together in a special way.
I was looking at a development web site I am involved with and I was interested in where the site was in the big bad world, so I decided to traceroute to it [1]. What seemed very unusual was that the 5th hop reported an IP address in the 10.0.0.0/8 private address space. To quote Sam “10.what now?”. I’m still amazed that packets with private source addresses are routed across the Internet![2]
I go to spinning quite a bit and I think I have had six teachers over the last year since I started. I think every teacher has one phrase they use most; this is not a bad thing, it’s just something I have noticed. I present an anonymous list of them here.
Since Christmas I have been up to loads. I went skiing in March and I went to Cuba in June. I have done well with resolutions, I managed to stay super healthy for January and managed to mostly keep to it since. However I utterly failed to read LWN :-(
It’s time for some new year’s resolutions! Hopefully if they are cast in stone (well blog) there is more of a chance of success.
I passed my amateur radio Intermediate exam, so now I can kick out 50W! My new call sign is 2E0TDS. My thanks go to all at SADARS that helped with the practical day and two days of lectures and exams. All I need now is some sort of radio!
Last week I got back from a little holiday in Dublin. I went over for my cousin’s graduation. I had an amazing time, it was a very relaxed and slow paced get away from everything. We went to all sorts of different cafes, restaurants and live music bars in the evening. It felt so luxurious to stay in a hotel in the centre of town, we were able to roll out of which ever bar we were in, hail a cab and be back home in no time. Coming back to a made bed and fresh towels can’t be beaten.
