Category Archives: system administration

Running Asterisk in the cloud with Amazon EC2

I have been sitting on a half post for a while now on setting up Asterisk on EC2 and then this past week someone else came out with a post on how to install Asterisk from scratch on EC2. I figured I would wrap up what I have since I take the path of installing Asterisk on VirtualBox first then converting that disk image to an AMI as I outlined a few weeks ago when I got serious about testing out the Asterisk on EC2 concept.

Reading over the comments on the Voxilla post you will see some concern about how cost effective putting Asterisk on EC2 would be. Even if the cost is an issue for normal use I think Asterisk on EC2 could work for bursts of outgoing calls or even temporary conferencing systems. Part of what I wanted to do was find the least resistant path to getting started so I went with Trixbox since it has a lot of tools pre-installed and support for Gizmo5 that was very easy to set up. The key with Gizmo5 is that it is cheap, works with Asterisk via SIP and you can have incoming calls for free from a land line so it is easy to test cheaply.

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Using scrub to destroy a hard drive

Recently I had a hard drive failure that pushed me into getting a little NAS device that I could back up to S3 easily. After consolidating a lot of data to the NAS I was left with a few old hard drives that I needed to do something with as well as some existing hard drives that I've collected over the years. Some of the drives I have are from family members that I have recycled computers for but kept the hard drives out of fear that personal data might still be on them. At the same time this was happening I read an article claiming that a single drive wipe protects data.

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How to transfer a Linux image from VirtualBox to Xen

There have been times recently when I wanted to pull a VirtualBox Linux instance I had into Xen. I kept thinking it had to be fairly easy but I kept putting off trying it until recently when I ran into something I wanted to install from a CD image into an Amazon EC2 AMI. It turns out the main hurdle in transferring an image is lack of documentation.

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Automounting Amazon EBS volumes on EC2 instances

I've been using S3 to store semi-transient information like log files from EC2 nodes in the past but recently decided to give Amazon's Elastic Block Store (EBS) a try instead. I quickly realized a downside to using EBS in that there is no mechanism for auto-attach and mounting volumes when an AMI is launched. This is probably something Amazon will fix at some point and allow you to launch a given AMI with an attached EBS volume but until then you need some way of doing it yourself. The following is a simple way of using ruby to make it happen.

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PowerDNS Makes Custom DNS Backends Easy

I ran into PowerDNS recently when I needed to find a DNS server that would allow me to produce custom responses to domain queries. I needed to have a request for a DNS entry return a different IP depending on some factors in a database and I needed that data to always be accurate (not cached locally). I found that PowerDNS allows for a lot of customization and I ended up using its piped backend for dynamic queries feature.

With this level of customization you can do things like write your own DNS black list, track who is making DNS requests, give out IP addresses based on a servers availability or use geographic information to return a different IP.

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FreeRADIUS with Oracle

I recently needed to find a RADIUS server for use in a project where I could stick profile data into Oracle. I remembered seeing FreeRADIUS a while back so I checked to see if it was active and supported Oracle. Sure enough it did. It was a little tricky to set up because some of the documentation is out of sync with the latest version so here is what you need to know to get it working.

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Examples of why netcat is still useful

I recently got a new work PC and was worried that stuck somewhere in the 40G hard drive of the old PC was something I would one day need. The new PC had 300G of space so I figured I would just copy the entire drive over and keep it forever. This isn't the most difficult task in the world and I actually started out using ssh to transfer the image.

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