What Is NAT Filtering? Everything You Need to Know

I’d love to get straight to the point, but I feel it’s important to discuss NAT (aka. Network Address Translation) before I explain what is NAT filtering.

NAT is a service that helps routers translate a group of IP addresses to another group of IP addresses. Its goal is to help preserve the limited number of IPv4 public IP addresses available for use. Typical translations involve a private network using IP addresses in a private range (like to, which works well for systems that only have authorized access to resources inside a private network. 

Today, NAT is present in all types of routers ranging from lower-end models to premium-tier devices. It also allows devices like your laptop, mobile, and smart TV to connect to the web with a single IP address offered by your ISP.

What is Nat filtering

Understood, But What Is NAT Filtering?

Put simply, NAT filtering is a defensive block that adds an additional layer of security to your internet network, protecting you against cyber threats.

You can think of it as a front-line soldier battling to prevent hackers from injecting malware into your devices.

Essentially, NAT filtering inspects data packets and then decides how to use them. This continuous monitoring helps it block any incoming internet traffic that isn’t a result of your request.

The NAT filtering process works like this: NAT transmits data packets to the internet from two separate devices. At first, DMS is used to pass data packets from a PC to a router. Then, a request allows for the sending of these packets to the destination service. The outcome? Your router receives data packets from the destination service. NAT filtering then analyzes these packets and transmits the clean traffic to your computer.

If any data packet comes from an unidentified source, it’s blocked by the NAT firewall – I’ll discuss that next.

What Is A NAT Firewall and How Does It Work?

A NAT firewall functions on a router to help secure private networks. It only permits internet traffic to pass through if the device present on the network requested it. Any unrequested data packets or requests are filtered to prevent communication with potentially malicious devices.

Also, if the incoming web traffic doesn’t hold a private IP address for forwarding beyond the gateway, the NAT firewall sees it as a red flag and discards the inbound traffic. That’s how it protects your devices from becoming a victim of a cyber hack.

NAT and PAT In-Network: What’s The Difference?

Most people interested in NAT also want to know how it differs from PAT (Port Address Translation) in a network. Essentially, NAT provides “one-to-one” translation between two IP addresses. And it’s typically used in organizations where IT wants to offer internal system access to the web via a unique public internet protocol address. NAT firewall’s table is similar to the following:,

In contrast PAT offers a “many-to-many” relationship, implying that all IP addresses within a company will rely on a single IP address. So firms that use PAT will want all of their personnel to use one IP address for connecting to the internet. They can do this by using a single IP address for all computers, but varying ports for separate sessions. PAT firewall’s table is similar to the following:  192.168.314 5004, 192.168.315 5005.

Changing NAT Type on NETGEAR Genie

If you have a NETGEAR router, you have the option to change the NAT type. Why should I do this, you ask? It’s because the NAT type can affect the stability, reliability, and performance of your internet connection. To change the NAT type to “OPEN” on NETGEAR Genie (the desktop app that allows you to configure NETGEAR routers), follow these steps:

  1. Open NETGEAR Genie on your Mac or Windows computer, tap “Start”, type www.routerlogin.net in search, and tap “enter”.
  2. Enter the password when prompted for authentication. If you haven’t yet set a password, write “password” without “ ”. Now tap the Log In button to proceed.
  3. In the left panel, tap “Attached Devices” under “Maintenance”.
  4. Look at the Device Name and IP Address fields to locate the IP address of your PC, gaming console, or mobile device.
  5. Tap the Port Forwarding link on the left then tap the “Add Custom Service” option.
  6. Put the name of the device or program with NAT set to Strict in the box titled “Service Name”.
  7. Click to expand the Protocol box and choose the relevant type for the program (or just choose “Both” if you’re not sure about the type”.
  8. Enter the IP address you took from Server IP and tap “Apply”. The router will now restart and the new NAT status will be “Open” on your NETGEAR router.

NAT Filtering on PS4

If you regularly connect to the PlayStation Network, and haven’t experienced any NAT errors on your console, consider yourself lucky and don’t make any changes in your router’s NAT settings.

NAT issues on PS4 occur due to communication errors between the console and the router or the server. NAT types in PS4 are classified as Type 1, Type 2, and Type 3.

Type 1 implies “Open”, Type 2 stands for “Moderate” and Type 3 means “Strict”. For interrupted online gameplay, your NAT Type should be Open. Those with Type 2 can experience some interruptions during gameplay. Type 3 is the worst, as it stops you from getting chat messages or hosting gameplay seamlessly.

NAT Filtering on Xbox One

It’s common for Xbox One owners to face NAT filtering issues. As a result, online gamers need to manually set the NAT type to Open when they get “Moderate” or “Strict” NAT settings.

If you’re using the NETGEAR router, you can resolve NAT filtering issues by following the instructions mentioned in this guide.

If you need to Open NAT on multiple consoles, the settings for it will be available and enabled by default (UPnP). But if you’re still experiencing an issue, try assigning an individual port. Also, disable your Geo-Filter when booting up the Xbox One to avoid false NAT readings.

With Open NAT settings, you should be able to communicate with other gamers and play online without interruptions.


NAT filtering might look complex, but it’s the most basic level of security present in an internet router. You can combine it with a VPN to achieve even more robust protection. But if you do, make sure to select a premium option like ExpressVPN so that you can enjoy benefits like blocking the inbound and outbound traffic when your VPN disconnects abruptly.