In most environments where I work I see poorly or not implemented at all Windows Defender Firewall with Advanced Security, even if since Windows Server 2008 and Windows Vista (well in fact a lot of things were there also before but not so intuitively configurable …) it provides great features that can drastically increase security in the network environments …

First of all it provides inbound and outbound filtering – with outbound rules you can do a lot to prevent your users accessing other devices inside your networks …

At least in Slovenia (yes, we are quite a small country where good old Small Business Server was widely adopted) there are still many companies that do not have real segmentation in place (with vlans for printers, users workstations, servers, network management, access lists between segments…) – and we all know that implementing it when you have everything in-place is quite an effort and a project that can take a lot of time…

Well while you are preparing for this step you can do a lot by using outbound rules on Windows Defender Firewall with Advanced Security and simply disallow your end users to access management interfaces of your network devices, you can prevent users to establish connection to servers on protocol that they do not need and so on …

For now we were talking just about basic inbound / outbound rules but what is that Advanced Security part in it’s name? Well we will cover that in next parts dedicated to this great piece of software that you all already have included in your operating system.

Today I would like to just quickly go through basic implementation that I will call Firewall baseline for client computers where I will just deploy a Group Policy object where I will configure Windows Firewall to be turned on and to ignore local rules – this is very important when you are deploying Windows Firewall – by doing so after Group Policy is applied all local rules will be ignored (also those that could be potentially created afterwards by user who has local admin rights) – only and exclusively rules that you define through Group Policy will be effective on your workstations. This is important to be sure that you are completely in control of what is going on on your workstations (and of course servers) firewall.

In the video you can see that at the beginning I am remotely connected to a client PC (that will get firewall settings later through Group Policy) and after Group Policy is applied RDP sessions in disconnected (as local rules are not effective any more (Apply local firewall rules: No) – and only after I add manual exemplary rule for RDP (tcp port 3389) RDP session* is reconnected.

*Yes, this rule is without any extra parameters and making such rule is not a good idea – as it opens RDP from anywhere to the workstation affected by this policy – it was created just for demo purposes for this video.