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January 6, 2014

Ubuntu Grub Error

Ubuntu Cola and a roll

More for myself than anyone else ..

While cleaning up the kernels and doing some updates on an Ubuntu machine you might get this error:

 you may need to re-run your boot loader[grub]

Not 100% clear to me, but the solution is pretty easy.

As root or using sudo run:

update-grub

Problem solved!

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August 24, 2013

Configuring Icecast Streaming Server On Debian

Conn and I did an experiment earlier this week with the technology.ie podcast. Instead of simply recording it and then publishing it we streamed the entire thing live using IceCast.We'd previously played around a bit with Google "hangouts', but running our own streaming server was fun and also gave us more autonomy.

Media streaming always struck me as being incredibly complicated and I thought it would be too complicated for someone to setup and run without a lot of work and knowledge.

However I was pleasantly surprised to discover that it's actually pretty easy if you have some basic knowledge of Linux and don't mind getting "down and dirty" in vim.

To setup a public streaming server you'll need to have a public server, which in my case wasn't a challenge, as I have a cloud VM from Blacknight (doh!).

I like Debian and the package management system it uses (Apt) makes installation of a lot of commonly used software tools incredibly easy.

In the case of icecast2 there is a readily available package so you can install it quickly and easily by simply running:

apt-get install icecast2

You'll be prompted to install Icecast and probably several other bits of software.

Configuring it isn't that hard and Falko Timme has written a very nice and simple tutorial. The main thing to remember is to switch the server "on" by editing the file in /etc/default/icecast2 - the last line needs to be set to "true".

Debian also comes with a functional init script so you can start the server off using (as root or sudo):

/etc/init.d/icecast2 start

It'll automatically switch to running as the icecast2 user and group.

So with a running instance of IceCast the next obvious step was finding some way of broadcasting.

Conn uses Butt, but it's a bit limited unless you have extra equipment.

I like simple. So I opted for Nicecast for my experiments. It's a very simple, yet powerful, bit of software for OSX. A license costs $59, but you can use and abuse it for up to 60 minutes of audio streaming before you need to purchase a key.

What I really like about Nicecast is that you can use it to broadcast any audio source you like, so if you want to broadcast from iTunes, Spotify, Last.fm or even your browser, you can do so. (Bearing in mind that you will need a license to broadcast copyright works)

You simply choose the source you want from a dropdown menu:

Choosing an audio source with nicecast on the Mac

Choosing an audio source with nicecast on the Mac

Obviously not all of the apps it identifies would have audio, but it doesn't try to second guess you. So if you had embedded audio into a Word document it'd let you set that as the source, which is very handy. I really hate it when software limits me!

Connecting to your remote server is pretty easy. You simply add the new server to the application:

Configuring a server in Nicecast on the Mac

Configuring a server in Nicecast on the Mac

 

When you're happy that the settings are correct you can then start your broadcast:

nicecast-before-broadcast

And now it's up and running:

nicecast-broadcasting-audio-via-itunesYour IceCast server's status will show you what it can "see":

icecast-broadcast-status

In my case I'm playing with the soundtrack from Elysium :)

So you should now be all set.

The total time to get it all up and running should be under an hour - the only gotchas I ran into was that the Debian setup was easier than I thought, so I ran into a couple of silly problems while looking for more complicated ways of starting the server. Also, if you use Nicecast don't put a trailing slash either before or after the mount point. The software will automatically add its own, but if you try to set one it'll break. So you'd end up with the odd scenario of having a stream that nobody can access, as the URL would be "empty" and the mount point wouldn't be visible.

I've no idea what, if anything, I'll do with the icecast server now that I've got it setup. Conn and I have been toying with doing a few other experiments, but we want to be sure that if we do anything beyond "talk radio" that the licensing is in order. The last thing I want to end up with is problems from IMRO / IRMA over copyright and licensing!

 

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July 29, 2012

Force SSH over IPv4 or IPv6

I've got an IPv6 connection at home via Sixxs which works pretty well.

Of course some of the time when I need to access certain machines from outside the office I'll run into issues ie. I can get in over IPv4, but not over IPv6. Other times the IPv6 connection from wherever I happen to be might not be as stable as the IPv4 one.

So being able to force an SSH connection over IPv4 (or over IPv6) is handy (and this is more for my own reference than anyone else's!):

ssh -4 user@hostname

Will force the connection over IPv4, while:

ssh -6 user@hostname

will force it over IPv6

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July 20, 2012

Updating Whois On Debian

Getting an up to date whois client on Debian is a requirement if you work in my world:

wget http://ftp.ie.debian.org/debian/pool/main/w/whois/whois_5.0.17_amd64.deb

dpkg -i whois_5.0.17_amd64.deb

Problem solved ..

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April 10, 2012

Linux Sysadmin Type Wanted

Image representing Blacknight as depicted in C...

Image via CrunchBase

We're hiring for a number of roles at the moment over in Blacknight

The latest one we announced was this one for a Linux Systems Engineer

Think you qualify?

Then please apply

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March 4, 2011

Checking Which Ports Are Doing What On Linux

From time to time it's handy to be able to see exactly which process is using a particular port on a Linux system - especially if you're debugging issues.

This command will let you see exactly what's going on - you simply change the port number:

lsof -i:80

If you need the standard port numbers you can check this list

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October 23, 2010

Postfix Mail Queue Management

This is more as a reminder for myself than anything else since I tend to forget Postfix commands unless I use them regularly.

To see all mails in the current queue:

mailq

To flush the mail queue run:

postfix flush

To remove all the mail from the queue (ie. delete it) run:

postsuper -d ALL

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July 11, 2010

Tweaking Spam Filters

I've been running my own mail server for this domain and several others for a few years. I could have used our main mail servers, but I like messing around with the server settings and trying out new things.

One thing that I hadn't been checking too stringently on my inbound email was SPF.
Sure, I had it set up on several of my domains so that anyone else getting mail from me would be "happy".
Switching it to more stringent settings and checking SPF inbound, however, has proven to be worth the few minutes it took to set it up - over 100 mails blocked in less than 24 hours!

I opted to install postfix-policyd-spf-perl as I'm using Postfix. Configuration was pretty easy - just adding a couple of lines to the main.cf and master.cf (the man page gives you the most up to date configuration settings)

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March 4, 2010

Ubuntu Gets A Visual MakeOver

Ubuntu, which is one of the more popular Linux distributions these days, has unveiled a completely new look.

It's got a new logo:
blackeubuntulogoAnd a whole new range of styles for just about every other visual asset associated with the brand, both online and on the users' desktops.

The new look is very slick compared to the "old" image of Linux distributions as being ugly, yet functional

Full details here

Thanks to Laura for mentioning it earlier this evening

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March 1, 2010

Cleaning Up Old Configs On Ubuntu / Debian

Debian OpenLogo

Image via Wikipedia

This is more for my own use than anyone else...

If you remove a package in Debian / Ubuntu you often end up with legacy configuration files lying around.

Running the following command removes all the crud left lying around your system and may fix silly issues that you run into. As it's Linux, there's probably about 10 other ways to do this!

Here's the command:

sudo aptitude purge `dpkg --get-selections | grep deinstall | awk '{print $1}'`

Enjoy!

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