Nothing at all to do with computers, this time.
Some people at LRUG asked about the circus show I'm in. So, here are the details.
Nothing at all to do with computers, this time.
Posted by digitalronin at 12:00 pm
[UPDATE] There seems to be a bug in Snow Leopard where changes made to the Airport interface's MTU do not persist - it just jumps back to 1500 immediately. To make the change stick, you need to do this in a terminal window;
$ sudo ifconfig en1 mtu 576
(Assuming en1 is your airport interface, and 576 is the MTU value you want)
Sadly, the change will not persist through a reboot, so you'll need to run the command whenever you boot up your mac.
I'm not a big fan of being spied on, so I've signed up to IPredator, the VPN service run by the people who brought us The Pirate Bay.
Setting it up on OS X is pretty trivial, and I haven't noticed much, if any, difference in network speeds. But, I did find myself unable to access certain websites. Notably my Basecamp site, which is quite inconvenient. I've got HTTPS turned on, and when using my VPN connection, I couldn't load the login page - it fails as soon as it tries to do the TLS handshake. Turn off the VPN, and everything is just fine. Some other sites behaved in a similar way - even some sites that weren't using HTTPS (although digging into the page content suggests that it is https elements on the page that were causing the browser to hang).
37Signals support, sadly, were no help in this case. But, I did find this page which suggested changing the MTU (Maximum Transmission Unit) setting of my TCP/IP connection.
That page talks about how to do this on Windo$e, but I found that the problem went away if I made the corresponding change on OS X. So, I'm posting this here in case anyone else finds it helpful.
First of all, in "Network Preferences", select your main network connection (I'm using wired ethernet), and click "Advanced".
In the advanced options, click "Ethernet" and look for the MTU setting. Change it from "Standard (1500)" to "Custom", and enter a lower value. In my case, I'm using 576.
Click "OK", click "Apply" and then disconnect and reconnect your VPN connection.
That's it. I can now access my Basecamp site via my IPredator VPN connection. I hope this helps someone else.
Have a happy & private Internet!
Posted by digitalronin at 8:36 pm
Packt publishing asked me to review "Zabbix 1.8 Network Monitoring" (Disclosure: They gave me a copy of the book. Other than that, I have not been compensated for this review in any way).
I've been using Zabbix for a few years to monitor a variety of systems. I like it for its small (initial) learning curve and the out-of-the-box graphs and reports. But, the kindest word I can use to describe the provided documentation is "minimal". So, I was pleased to see a book that tries to address this problem.
At just under 400 pages, there's a lot of material. The book takes a tutorial approach, going from installation through to fairly advanced monitoring ideas including distributed monitoring with Zabbix proxies.
The book's target audience is sysadmins (aka "devops") and developers who have to do their own monitoring. So, the level of assumed technical ability is quite high. As usual with technical books, this can lead to over-explanation of some steps and under-explanation in others. But, I found the tone and level of detail struck quite a nice balance. YMMV, of course.
As well as covering the detail of the steps you need to take to setup Zabbix and start monitoring, there are good explanations of the high-level architecture of how the various Zabbix components fit together and communicate, which I found very helpful.
The author, Richards Olups, works with Zabbix SIA (who develop Zabbix), and his in-depth knowledge of the system is obvious throughout the book.
For example, I was pleased to see a section about digging into the underlying database Zabbix uses to store configuration and historical values. Zabbix's PHP front-end is functional, but can be a bit quirky. IMO, it's ripe for replacement/augmentation with something a bit slicker - maybe a Rack application using some Flash-based graphing tools. Having a guide through the database structure will make it a lot easier to create something like that.
Also nice are some tips about using the unix command-line tools to help troubleshoot monitoring problems. e.g. using telnet to connect to the zabbix-agent process to confirm it's listening correctly for connections from the server. This is basic stuff, but a worrying number of developers (and even some sysadmins) I've met don't seem to have much awareness of the toolbox unix provides.
The section on how to upgrade Zabbix and patch its database is also a nice inclusion. A quick glance at the Zabbix support forums shows that that is often a problem area, so I like the fact that this has been addressed upfront. Using Zabbix to monitor its own health is also covered, and the section contains lots of advice that would have saved me at least one weekend spent rebuilding my monitoring from scratch when an earlier version of Zabbix decided to eat its database, one day!
As you can probably tell, I like this book a lot, which is just as well since it appears to be the only book on Zabbix available right now.
There are a few nitpicks, perhaps. The step-by-step tutorial approach makes the book far more suited to being read through rather than as a reference, but since this is the first book available (AFAIK), I think that's probably a good choice. I would have liked to see Ubuntu covered in the installation section (the author covers compilation/installation on SuSe and Slackware), although the book's target audience shouldn't have any trouble adapting the instructions for their distro of choice. The writing and grammar are a little quirky, and a glossary would have been useful. But, these are really minor points.
Overall, I think the book has a lot to offer anyone who is using, or thinking of using Zabbix as their monitoring solution. If I hadn't been given a copy, I'd probably buy it.
Posted by digitalronin at 11:01 am