The firewall is between your computer and the network it is on, or between your network and the Internet. It exists to allow specific types of traffic, often identified by the port they use, to pass through and block everything else.

Your LAN includes any device that is connected to your home router, either via Wi-Fi or a wired Ethernet connection. Each device is assigned an IP address by your router, which uses NAT (Network Address Translation) to route traffic to and from all these IP addresses to the world through your “external global IP address” – the address provided to you by your Internet service. supplier.

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If the router receives all the traffic, no matter who it is or where it goes, then everyone outside will have access to everything on your network. This is obviously a terrible idea, so your firewall stands in the way.

It will not play anything on the wider Internet unless a computer on your network explicitly requests that the connection be made. Anything you actively want to serve data on the wider Internet, such as a web or email server, is assigned to a DMZ (demilitarized zone) that is outside the firewall. Instead, more complex implementations may place the DMZ behind a different, less restrictive set of firewall rules separate from the local network.

But what if you have to allow outside traffic? Then configure the firewall to skip it using the “firewall rule”. You will usually do this using the port forwarding settings on your firewall.

Some ports have specific functions for which they are reserved. Port 80 for web traffic and port 22 for secure shell access, for example.

Others, you will need to open manually using the port forwarding settings on your router. You tell the router which external port facing the Internet should also open the IP address of the local device to which it should route all data sent to that port. You will also want to define which port on the local device the traffic goes to so that it is routed to the program that listens to it.

If you want to be able to use the Remote Desktop Protocol (RDP) to connect to a Windows computer on your network when you are elsewhere, you will need to open port 3389. The default port for a dedicated Minecraft server is 25565.

Although you can often assign more or less any port you like (except saved ones) to everything, sticking to the default settings has advantages. However, it can also make you more vulnerable to anyone specifically trying to hack into poorly secured examples of services that use these ports. Never use default usernames and passwords for services you reveal on the Internet.

Your router’s NAT firewall has other features, such as the ability to block outgoing traffic if you wish. You also configure your firewall to allow all traffic from a specific IP address to access parts or your entire network. This can be useful if you need full access to one network you own from another network you own that has a different IP address.

So this is your network firewall. It does a great job of protecting you and is worth having a decent one so you get the right configuration interface with many options.

Windows also has a solid firewall that is turned on by default.

This is a lot for Windows. Linux distributions and macOS have software firewalls, but do not enable them by default. Instead, if a service in the system does not explicitly use a “listen to” port, it will not respond to any external attempts to connect to it, effectively preventing any unwanted communication or access.

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Windows Firewall does more or less the same thing as Network Firewall, but only takes care of the computer you’re running. By default, Windows Firewall in Windows 10 and Windows 11 blocks all incoming connections that do not conform to a specific firewall rule

It’s also a little more interactive, so if you initiate a connection that uses a particular port, it may ask you if you want to open that port or not, and it will add a rule that allows that connection if you say yes. However, this is not always correct, so you may need to manually open specific firewall ports using Microsoft Defender Firewall settings.

What is a firewall?

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