Windows Defender Firewall is a built-in personal firewall and is available for most Windows versions. In this video, you’ll learn about the Defender Firewall configuration options and how to create your own customized firewall rules.
We’ve become very used to turning on our computer wherever we happen to be, and it automatically gets an IP address. This might be on our local network at home. It might be in a coffee shop or a hotel or anywhere else we might happen to go. Our computers are able to receive this automatic IP addressing through DHCP, or Dynamic Host Configuration Protocol. This is the default setting for most operating systems, and it makes it very easy to obtain an IP address and immediately connect and use the network.
If a DHCP server is not available and a manual or static IP address has not been configured on a workstation, then your machine will decide to create its own IP address based on APIPA. This stands for Automatic Private IP Addressing. You might also hear this referred to as a link local address because this is a type of IP address that can only communicate on its local network. If you’re assigned an APIPA address, you’re not able to communicate across the internet.
One way to tell if you’ve been assigned an APIPA address is to look at the IP address on your workstation, and if it is between the range of 169.254.1.0 through 169.254.254.255, then you have been assigned an APIPA address. There may be certain situations where you always want a device to have exactly the same IP address every time you turn it on. We refer to these as static addresses. These might be manually configured on a local machine, or you might have that particular device configured with an address reservation in your DHCP server.
To be able to configure the static address manually, you’ll need to know information such as your IP address, subnet mask, and default gateway. Those three values are the most important when you’re configuring TCP/IP on a device. That IP address is a unique identifier that’s specific to that computer. A subnet mask helps define what IP subnet this device is connected to. And a default gateway is a device that is routing your local network traffic onto networks that are outside of your local subnet.
You’re also often configuring a DNS, or Domain Name Services, IP address. This is the device that converts that fully qualified domain name to an IP address. So instead of having to remember what the IP address is of my web server, you simply type into your browser www.professormesser.com, and behind the scenes, this DNS server is able to convert that fully qualified domain name to its appropriate IP address. And we’ve already seen that many devices will obtain all of this information from a centralized database of IP addresses, called the DHCP server, or Dynamic Host Configuration Protocol server.
One interesting address that’s important to know for IP version 4 is the loopback address of your computer. The loopback address is 127.0.0.1, although technically it’s any IP address that’s on that 127 network. This is an address that defines the internal IP address of your computer. It’s on every single computer, and it’s a way that you can confirm that the IP stack of your device is working properly.
At home, you probably have a single DHCP server, and it’s probably integrated into an existing internet router. If you’re in a business environment, it’s common to have multiple DHCP servers. Because that is such an important service to have available, we want to be sure there is redundancy if we happen to lose one of those servers. But there may be times when you want to configure your device to use DHCP. But if a DHCP server is unavailable, you don’t want your computer configuring itself with an APIPA address.
Instead, you want to use a predefined alternate configuration, and that is one that you would add to a separate tab inside of Windows. You can make this a separate automatic IP address for DHCP, or you can manually configure all of the settings under that alternate configuration. Let’s add an alternate configuration to my computer. I’m going to go into the control panel, and I’m going to choose the options for Network and Sharing Center. Inside of the Network and Sharing Center, I’ll choose the options to change adapter settings.
You can see I have a single ethernet adapter in this device, and if I right mouse click, I can choose the option for properties. Inside of the properties, you can see that there is an Internet Protocol Version 4 available. And if I choose the properties of that option, you’ll see that a manual IP address configuration is currently selected with 10.1.10.102. It would be much easier if I could have this device automatically obtain an IP address. And if DHCP is not available, I could have an alternate configuration for the 10.1.10.102.
So if we click the option to obtain an IP address automatically, the Alternate Configuration tab is now available. If we click Alternate Configuration, we can now set a user configured IP address. For example, this might be where I add my 10.1.1.102 IP address, and that will be my alternate configuration if a DHCP server is not available. We’ll now add in the subnet mask for all of these, which is 255.255.255.0. And the default gateway is 10.1.10.1.
We can also specify DNS servers in here in the alternate configuration. For example, I might want to put quad9, and that might be the default I would have for my alternate configuration. We can click OK and click OK again. And now we’re back to where we started. This is now going to check the configuration of the settings that we just added. It’s going to change this to a DHCP configuration. And it’s going to include the alternate configuration in the case that DHCP is not available. Now, if we go back and look at the properties of that configuration, it now has the IP address automatic configuration and includes the alternate configuration inside of Windows.