Tag Archives: type

Using schroot instead of LXC containers

So, I have been using LXC to host my server services for a period of time, with a view to keeping things portable should I need to change provider. It’s very good in that it’s integrated into the Linux kernel and in Ubuntu at least it’s not too difficult to setup, however there are a number of problems with it.

First and foremost, every time the container operating system upgrades anything to do with init scripts, it won’t boot any more, so you are forced to hold back packages with varying amounts of success. Secondly, there does seem to be some overhead running things in an LXC container, and thirdly it isn’t as portable as it could be i.e. there is no live migration. and you will have to change config files if you move hoster to reflect you new IP address.

As I’m not selling containers as VPS, I only need to run 1 server instance, and therefore don’t really need containerisation at all, enter schroot. Schroot is like chroot without the hassle and with added flexibility, in a nutshell it will mount and start everything correctly for you to the point where you can automate startup and running of services in the chroot, it doesn’t suffer from init script borkage since the init system isn’t used at all, and it’s more portable as networking is irrelevant to a chroot (it simply uses the hosts networking).

Ok so where to start, well if you are already using LXC you can use the directory your container is stored in. I opted to move mine to a sane location before starting, in the interests of convention and easy administration. So, I created a “schroot” directory in the /home directory i.e.

 mkdir /home/schroot

Continue reading Using schroot instead of LXC containers

Stream a DVD in Ubuntu

In order to watch a DVD on a device which doesn’t have a DVD drive, it’s possible to stream it from another device which does, through the network. For instance in our house we only have one laptop with a DVD drive. This is the main and most powerful machine which I use for day and nighttime work. When the children want to watch a DVD upstairs in bed (we don’t allow them have TV in their room) I use VLC to stream from my laptop, instead of playing directly, so I can keep working away.

Before we start, obviously, make sure VLC is installed on both devices either by Ubuntu Software Center, Synaptic or apt-get, whichever takes your fancy. On the machine with the DVD drive, we’ll call this the “server”, you simply type/paste one command in, then at the drive-less end, let’s call this the “client”, you run the VLC GUI and tell it where to listen for the stream. So on the server type/paste:-

Continue reading Stream a DVD in Ubuntu

LXC firewall logging and udev upgrade in Ubuntu

Today I’m going to write about a couple of major gotchas with LXC. Now these issues are documented in various places but I wanted to put all the relevant information together in one place to make it easier for people.

Before going any further it’s important to note that I created my LXC container with the official Ubuntu template from the latest “stable” LXC release i.e. I downloaded the tarball and put the template in the correct place as Ubuntu 10.04’s LXC package doesn’t contain said template. This helps minimise all sorts of problems especially ones related to the LXC console crashing and the like.

Firstly you will find when running “apt-get upgrade” (if you have Lucid updates enabled in /etc/apt/sources.list) that you get this error on upgrading udev:-


mknod: `/lib/udev/devices/ppp': Operation not permitted

Continue reading LXC firewall logging and udev upgrade in Ubuntu

Converting to GPT in Ubuntu

GPT stands for “GUID Partition Table” and it refers to a relatively new format for disk partition tables. It was designed to get around the limitations of the MBR format, namely that you can have more than 4 primary partitions and partitions can be more than 2.2 terabytes in size. GPT is part of the EFI standard but it can also be used on standard BIOS only machines i.e. most non-MAC PCs. Converting to GPT will allow you to future proof your partitions. 2 TB disks are becoming common and it won’t be long before the 2.2TB limit of MBR will stop people using all their disk space in one partition, so in the name of usability and flexibility GPT is the way forward.

Continue reading Converting to GPT in Ubuntu

SIP Communicator the only show in town for VOIP in Linux

I have been trying to reach a holy grail. Well, not a big holy grail and to some people this will seem silly, but I have been longing to be able to use VOIP in Linux and until I discovered SIP Communicator it wasn’t viable.

Ekiga the default VOIP soft phone in Ubuntu just doesn’t cut the mustard. It crashes is difficult to setup and just plain doesn’t work properly for me (I have a mobile broadband connection so jitter is an issue).

As for Twinkle I couldn’t even get it to work. Qutecom was the best soft phone I had used. It crashed a lot on start up, would crash sometimes in calls but at least it was easy to setup and worked up to a point. And then, while trying to help somebody on the Ubuntu forums, the poster, after tearing his hair out trying to find something that just works recommended SIP Communicator. I thought I would give it a try and it was and is a revelation.

Continue reading SIP Communicator the only show in town for VOIP in Linux

Wake On LAN over wireless

What is it?

Wake On LAN is a mature technology for switching on computers over a network or remotely.

Why would I want it?

Perhaps you are a techy such as myself and you want to be able to switch customers computers on and work on them remotely (saves having to tell people to leave machines on if you are working after hours).

I also use it to switch on my Ubuntu machine upstairs when I am downstairs (saves me or my better half having to wait for boot or to get a file to or from the machine without physically going up there).

Is it easy to do?

Yes when you know how ;)

Before I go any further I will mention a caveat. Almost all of the WOL howto’s out there mention using a “magic packet” packet to wake the machine. Unfortunately I found out after much head banging and googling “magic packet” doesn’t work over wireless networks, apparently because wireless frames screw the magic packet up so that the wakee doesn’t recognise it any more.

So if you want to use WOL by sending the wake up through a wireless network your options are limited and it depends on the network card you have. At least 2 of the cards I have support a variety of WOL options “pumbg” and the other one only supports “pg”.

  • P stands for PHY activity
  • U stands for Unicast activity
  • M stands for Multicast activity
  • B stands for Broadcast activity
  • G stands for Magic Packet activity

Firstly I tried phy activity that had the unfortunate effect of starting the machine every few seconds. Then I graduated to broadcast which started the machine periodically (my thick wireless router is sending out broadcasts every hour or so). Eventually I settled on unicast here is how to get it working.

Continue reading Wake On LAN over wireless