Category Archives: Servers

Windows : Install Ubiquiti Unifi SDN Controller as a service

If you are operating Ubiquiti wireless gear compatible with the Unifi controller, and running it on a Windows machine, you may have noticed that you need to start the application manually every time you restart the computer. Fortunately, there is a way of adding it “as a service”, just like any OS/system services. Follow the… Read More »

Linux : There is no screen to be resumed matching …

Using “screen” on Linux to perform your important work? Way to go, SysAdmin 🙂 Then you might at some point encountered the following behavior – while attempting to resume a session using “screen -r”, the following message occurred : There is a screen on: (25/08/18 08:25:36 PM) (Attached) There is no screen to be… Read More »

Linux : How to get hardware serial number

The easiest way to get hardware serial and related information is using “dmidecode“. The command below should give you exactly what you need :

The command above does not usually work with “clone” computers/servers. Alternatively, you may use the command below, which will output all parts serial number availables :


Windows : Upgrade the Ubiquiti Unifi SDN Controller

This tutorial will show you the simple steps to upgrade your Ubiquiti Unifi SDN Controller running on Windows. The software can be found on the manufacturer Web site ( We recommend using the LTS (Long Term Support) version unless you need the bleeding edge features. Upgrading to newer version might not allow downgrade in case of… Read More »

Windows : How to retrieve Fiber Channel interface WWNs

Here is a simple PowerShell command that will output the FC host adapter interface WWNs.

If your interface have two ports, both will be output in order. This command have been successfully tested with QLogic adapters on Windows 2012 and 2016.

Linux : How to show domain TTL with DIG

Here is some useful commands to display a domain Time To Live (TTL) using the DIG command (which is usually included within “bind-utils” package). To display the full information :

To display the short, default answer :

NOTE : Replace “domain.tld” by the domain you want to query.

Windows : Change DNS update frequency in Active Directory

If you are not satisfied with the refresh rate of DNS within your active directory environment, there is a way of forcing it by increasing or decreasing the default setting in the registry. First of all, there is a command to find out your curent settings :

It should output something similar to :… Read More »

Windows : How To get the members of a group in Active Directory using PowerShell

Here is some useful commands to list the members of a group in Active Directory using PowerShell. Get members of a group :

Get members of a group, recursively (to list all members of sub-groups members of that group) :

NOTE : Replace “Group Name” (keeping the double quotes) with the desired Group… Read More »