Category Archives: Uncategorized

General blog posts

360Radar – military aircraft in the UK

In this post I talked a little about 360Radar, a flight tracking website aimed mainly at the UK.

Most military aircraft flying around the UK do not transmit their long/lat position like commercial flights. Instead some (not all) just transmit limited information.

If this is information is received by 3+ ground stations (like as Raspberry Pi running dump1090) then the position of the aircraft can be calculated using a technique called multilateration (MLAT).

This is what 360Radar do, showing the results on a browser based map. Here’s an example of what you can see with a few Tornados (TOR), a Gazelle (GAZL) and a couple of Grobs flying around. It’s also common to see Eurofighters and Hawks showing up –

FreePBX hosting

This is to confirm that SysAdminMan no longer offers FreePBX or A2Billing hosting.

There were a few reasons for this decision but one of that main ones was, in my opinion, Sangoma’s aggressive commercialisation of FreePBX and their “FreePBX” trademark.

It did not make commercial sense to continue building a business under these circumstances.

According to Google Analytics there are still a couple of thousand visitors a week that use the site, so I will leave it here, but will not be adding new guides or tips.

Linux and new SSD drive in Acer Chromebook C720

Acer C720I’ve been using a Acer Chromebook C720 as my travel laptop for a few months now. It’s a really nice machine for web browsing and e-mail. It’s lightweight, keyboard is OK and battery lasts for ages.

It will play video fine and the screen is bright and responsive, but you obviously wouldn’t want to use it for anything too intensive.

It’s a Chromebook so just has the Chrome browser available by default. There are a couple of ways to get Linux running on it though. The first way, and the way I’ve been doing it for the past few months is Crouton –

This installs LInux on top of Chrome OS. So to run Linux you first boot into Chrome OS, then type a couple of commands in the terminal to start Linux. There are a couple of downsides … first it’s a bit fiddly to start Linux and second it relies on the drivers of Chrome OS. So the network, sound, screen etc are all setup inside Chrome OS, and then your Linux instance just uses those connections. I found that you couldn’t use it as an OpenVPN client because of this. Also I had issues with the sound and screen brightness sometimes conflicting because of the Chrome OS settings. Continue reading

SysAdminMan website analytics

It’s been just over a year since I posted an update on the number of visitors to the SysAdminMan website, so I thought it was time to do it again!

Below are some stats from the SysAdminMan blog, which includes mainly FreePBX and A2Billing documentation.

When I posted last year there had been just over 75,000 unique visitors in the previous 12 months, and things are still growing with around 115,000 unique visitors this time

Unique visitors

Unique visitors

Continue reading

Connecting Yealink T22P to Asterisk using OpenVPN

Recent firmware versions for the Yealink T22P include the ability to connect to an OpenVPN server. This encrypts the traffic between the phone and Asterisk server. It also removes any NAT/SIP issues.

This guide was written using a SysAdminMan VPNPBX VPS and a Yealink T22P with firmware

Different Yealink models, or the T22P with different firmware may behave differently!

The SysAdminMan VPNPBX comes with a script for creating the certificates and config file required to connect a Yealink T22P to an OpenVPN server. To create a certificate log in as root and then run …

cd /usr/local/bin
./ yealink1 [email protected]

Where yealink1 is the name of the phone you want create (you should create a new certificate for each phone) and [email protected] is your e-mail address. The config file, called openvpn.tar, will then be e-mailed to you.

Next we need to load this config file to the phone. I recommend performing a factory reset on the phone before doing this.

Log in to the GUI of the phone and select Network / Advanced –

yealink config
Continue reading

Getting started with OpenVPN and FreePBX/A2Billing

OpenVPN is a VPN system that works on many different clients. This guide will go through getting started with the Windows client, others will be very similar.

The first thing you need to do is install the Windows OpenVPN client. This can be downloaded at –

Once installed we need to get the certificates for our OpenVPN connection. By default 3 files are created. These are –


Continue reading

Using SysAdminMan OpenVPN template with pfSense

I’ve had a few customers recently using the SysAdminMan VPN:PBX template with an existing on-site pfSense gateway. The VPN:PBX template has Asterisk, FreePBX and A2Billing installed, along with OpenVPN setup to allow secure connections to the VPS.

pfSense can be used as an OpenVPN client/gateway so this makes a great combination for a secure off-site PBX.

Here are some setup instructions for configuring pfSense with the SysAdminMan VPN:PBX template.

1 – Obtaining the OpenVPN client certificates

When your SysAdminMan server is created 3 files will be generated that are required to configure pfSense as an OpenVPN client. These files can be e-mailed to you or retrieved from the VPS using a program like WinSCP. The 3 files are –


These 3 files identify an individual OpenVPN client. If you are just connecting a single gateway this is all you will need. If you’d like instructions for creating more certificates please open a support ticket.

2 – Installing the Certificates on pfSense

Next we need to install the 3 certificates above in pfSense. The 3 files (ca.crt, tplink.key and tplink.crt) are text files which we can open with notepad, or something similar, and copy and paste the contents in to the correct place in pfSense.

First select “System/Cert Manager” from the pfSense menu. Then we click to add a CA –

pfsense add CA

Continue reading

Tech-Vets podcast

I’m a big fan of podcasts. If you commute, or are able to listen during the day while working, it’s a great way to keep up to date with what’s going on in the tech industry.

This month SysAdminMan is sponsoring the Tech-Vets podcast which is produced by Mike Smith and Carey Holzman where they talk about their experiences of running two small IT businesses. Even if you’re not in exactly the same market it’s often an interesting discussion on getting and retaining customers and the general ups and downs of running your own company.

As there is not too much focus on current technology the previous episodes age well. Why not check them out here –

My other favourite podcasts are –

Security Now –

FLOSS Weekly –

Linux Outlaws –

This Week in Tech –

VOIP Users Conference –

And if you’re looking for an App on Android to use for listening and managing podcasts then check out BeyondPod in the Google App Store

Website changes – mobile friendly

Over the Easter break I decided to update the website to give it a cleaner and fresher look. One of the main aims was to make it look nicer on mobile devices.

According to Google Analytics in the first 3 months of the year there have been 2,263 visitors to the SysAdminMan Blog that have been using a mobile device. Still only a very small percentage of the overall visitors, but the old site did not scale well at all on these devices.

Hopefully the new site will give these visitors a much nicer experience. If you have any feedback or suggestions on the new site please leave a comment below. Thanks!

Google Analytics mobile devices