Are you looking for tips on doing this with Ubuntu 9.10 (Karmic)? The procedure is different! See the updated blog post here.

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FreePBX is a popular front end for the Asterisk PBX system written in PHP. It adapts the complex yet very flexible Asterisk configuration system into something easier to use (yet still very extensible). When I worked for a business-class VoIP provider back in the day, we used FreePBX (and its predecessor, AMP) for most of our customer-premise PBX servers. I do like using FreePBX to configure my Asterisk system. However, I can't justify an entire server for Asterisk, so I need it to coexist with a number of other applications. What I can justify is a VPS with relatively little memory, so some tuning is required.

Rationale

The usual installation instructions assume the use of CentOS, Apache and mod_php for the stack. There are a few downsides to this configuration.

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Since mod_php runs the PHP interpreter "within" Apache, it is restricted to running PHP code with Apache's permissions. For the purposes of FreePBX, which needs to edit configuration files owned by the "asterisk" user, this means setting Apache to run as "asterisk." Not an ideal configuration from a security standpoint, especially when the server is not dedicated to Asterisk. The PHP folks strongly recommend that Apache use the prefork MPM with mod_php due to threading concerns. This is not a big deal for a dedicated Asterisk/FreePBX server, but if you're sharing it with a web server that might have popularity and limited memory, this can be a problem under high load. For this reason, I use lighttpd and PHP via FastCGI to service dynamic PHP content. This allows the web server to run threaded while PHP does its own thing, running under more specific uids. I've also found the availability of software for CentOS to be lacking, so I've standardized on Ubuntu to avoid straying from the repositories as much as possible. As of this writing, I'm using Ubuntu 8.04 LTS on servers and Ubuntu 9.04 on desktops, although I am using 9.04 for this example. So, time to get FreePBX operating properly in an entirely foreign environment!

The setup

The following was used as a base for this installation:

• Server: Linode 360 Xen-based virtual private server
• Distribution: Ubuntu 9.04, 32-bit

The steps

I'm starting from the beginning, as I am doing this in a testbed. You can probably skip some steps if you already have a working system. Additionally, you might want to browse http://library.linode.com/ for more general advice on deploying, securing, and configuring a general purpose server.

Prepare the system

I used Linode's Distribution Wizard to deploy a barebones Ubuntu 9.04 image using the defaults. First, I log in and do my normal Linux prep:

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You may also want to set your timezone, configure your IP address statically, and change your hostname.

OPTIONAL: Configure the system to use Ubuntu's stock kernel

To make Asterisk's MeetMe subsystem happy, one needs the ztdummy kernel module to provide timing. This is optional, and can be done with the stock Linode kernels, but you can run your distribution's stock kernel via PV-GRUB and thus "do what needs doing" without compiling.

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If you're running Ubuntu 9.04, you'll then want to edit /boot/grub/menu.lst per the instructions in Linode's wiki; in short, change groot=biglongthing to groot=(hd0) and set indomU=false, then run update-grub again. You don't need to uncomment the lines. You will also want to edit /etc/event.d/tty1 to change:

 exec /sbin/getty 38400 tty1

to:

 exec /sbin/getty 38400 hvc0

In Linode's dashboard, click on your configuration profile and change the kernel to pv-grub-x86_32. Save it, send a reboot, and watch the fireworks via the lish console. Getting an error on boot like "close blk: backend at ..."? See comment #3 from Quinn Ebert, below.

Installing Asterisk

You can download and install Asterisk from source, but if you're a wimp like me, Ubuntu's packages work just fine:

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If you need ztdummy, and are using the Ubuntu kernel per the pv_grub instructions above, now is a good time to grab the zaptel stuff. module-assistant will pause to install anything it needs to produce the zaptel kernel modules.

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Note: if it fails due to:

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... you are probably running into Launchpad bug 353024, which is an incompatibility between zaptel and the 2.6.28 kernel. Grab patched zaptel and zaptel-source packages from Darik Horn's PPA to fix this for now.

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Time for a Courtesy Reboot

Alrighty, you've installed Asterisk and Zaptel, it's probably time to do a reboot to make sure everything comes up right.

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Go grab a sandwich and come back in five minutes. It's time for a breather. When it comes back, make sure lsmod still shows ztdummy and Asterisk is still running. Is it? Good.

Installing lighttpd, PHP, MySQL, and FreePBX

It's time to install our web server, lighttpd, as well as the necessary muffins to execute PHP code. As mentioned above, we're using the FastCGI method to handle PHP requests. We'll also grab MySQL, and the necessary libraries to tie it all together. MySQL will want you to set a root password; remember what this is, for you will need it later on.

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Also, before we get too far down the road, let's save a copy of /etc/asterisk/modules.conf. There's a bit of a difference in philosophy between Debian/Ubuntu and FreePBX as far as what should be in this file. You'll need to copy this back in later...

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With luck, you should now be able to connect to your server on port 80. Let's go ahead and get FreePBX going. I'm going to adapt the installation instructions for CentOS here. Grab the URL of the latest version from FreePBX's web site; as of this writing, it's freepbx-2.5.1.tar.gz. Put that over in /usr/src.

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The following database initialization commands will ask for your MySQL root password you entered when you installed MySQL above. This is to test your memory ;-) You'll also need to set a password for communication between FreePBX and MySQL... enter this instead of "secret" in the GRANT commands below.

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Now, let's fire off the FreePBX installer. (Oh boy.)

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Wow, that was fast and furious. Wow. Don't bother going to that URL just yet; we'll get there soon enough. Let's make a couple tweaks to configuration files. First, edit /etc/amportal.conf. This holds the configuration for FreePBX itself, and we want to change "AUTHTYPE=none" to "AUTHTYPE=database" around line 57. Second, pop open /etc/php5/cgi/php.ini. Change memory_limit = 16M (around line 270) to 100M, and change magic_quotes_gpc = On to Off (around line 457). This will make FreePBX happy. Before I forget, let's install a mail transport agent so e-mailing of voicemails and FreePBX plugin update reminders can work.

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Making it all work

Right now, FreePBX is installed and in control of Asterisk, Asterisk is installed and should be working, and lighttpd is there. However, we do need to do some more work to get the lighttpd/PHP/FreePBX chain working. Using the current version of lighttpd in its default configuration, it will spawn its own PHP handlers (see /etc/lighttpd/conf-available/10-fastcgi.conf to see what I mean). Unfortunately, it can only spawn children as www-data, its own username. This makes privilege separation difficult. To fix this, we're going to start our own php-cgi handlers with asterisk's username, and tell lighttpd to use them when requests come in for FreePBX. We'll do this by adding a line to rc.local and by creating a configuration module for lighttpd. To /etc/rc.local, I added (before the exit 0):

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This, on boot, starts php-cgi to listen on localhost:4001 with two children spawned. Additionally, and importantly, it is running as user and group "asterisk". This gives the FreePBX scripts the opportunity to modify the Asterisk configuration. Go ahead and run the spawn-fcgi line now (as root), to get things going. (It might be a good idea to do this from an init script instead, so stopping/restarting is easier. This will be your homework.) Now, lighttpd needs to be made aware of your fastcgi handler. I do this by creating a file called /etc/lighttpd/conf-available/10-freepbx.conf:

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Change line three (the $HTTP["host"] line) to match the hostname or IP address with which you'll be accessing FreePBX. Now, a couple permissions tweaks...

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Then, enable the module and restart lighttpd!

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You should then be able to go to http://yourhostname/freepbx/ and access the FreePBX server by clicking on FreePBX Administration. Hooray! Click on the big "Apply Configuration Changes" banner and life should be good. Remember how you copied /etc/asterisk/modules.conf a little while ago? Let's go ahead and put that back in.

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This would be a great time to reboot and make sure everything comes back up! You can now add extensions, trunks, et cetera as you normally would with FreePBX! Head over to the Getting Started documentation on FreePBX's site and have fun! If anything didn't work right, or if you have questions, feel free to comment below and I'll take a look.