NAT Firewall: How it Operates

Multiple private-networked devices can connect to the internet via a single gateway, thanks to NAT (Network Address Translation). In addition to their special IP addresses, these devices will share a single public IP address. You will find these type of gateways in WIFI routers and some VPN services. For instance, all devices linked to a NAT-enabled WIFI router will share the router’s public address plus their unique IP addresses.

During a website visit, your device probes the router, using its private IP address for identity. The website’s server receives a translated request from the router with the public-facing IP address, keeping track of the address of origin. The server sends the website copy to the router, which is transmitted to your device through the private IP address.

A firewall is a protection layer that stops unauthorized communication between networked devices. A NAT in firewall works to allow communication only on the request of a private-networked device. All other unsolicited traffic is deterred to prevent connection to potentially risky internet devices. Without forwarding a private IP address beyond the gateway, NATs in firewalls identify and isolate unsolicited inbound communication to be discarded.

Signs you Have NAT in Firewall

How can you tell a NAT firewall is enabled on your Wi-Fi router? Connect two devices, such as a smartphone and a computer, and Google search your IP on each.

If both searches bring up the same IP, you’re most likely behind a NAT firewall. While your devices’ local IP addresses differ, the public IP addresses are the same.

VPNs may pose a challenge in determining the NAT firewall status, but most service providers avail the information in the documentation. You may opt to activate or deactivate the NAT in firewall in some VPN setups, or purchase it as an additional feature in others.

Each machine in a network would need a globally unique IP address if they were to all connect to the internet directly. The more typical option, however, is to have one gateway handle all the internet connection for every machine connected to the network. In this case, each computer needs a unique IP address within that network.

VPNs and NAT Firewalls

A Virtual Private Network (VPN) encodes a device’s internet traffic and channels it through an intermediary server in any location a user chooses. Because the traffic sifts through the VPN before it gets to the internet, the NAT firewall might fail to tell the unsolicited from solicited traffic. So, your router’s NAT firewall becomes obsolete since everything passing through the VPN looks just the same.

Thus, many VPN’s have in-built NAT firewalls. This saves your Wi-Fi router the hassle of filtering out unsolicited traffic. They may come at an additional cost or by default with the VPNs. However, VPNs and NAT firewalls may not be an ideal choice for all.

VPNs with NAT firewalls allocate themselves unique private addresses, making Wi-Fi routers with a NAT firewall a go to option for secure VPN connections. Even though you are safe from unsolicited traffic, the VPN provider or a third party can still track your device.

Port Address Translation (PAT) is similar to NAT in that they use a single gateway IP to represent many devices. NAT firewalls, however, confuse most PAT firewalls. Instead of private IP addresses, PAT firewalls issue computers or devices with port numbers.

How does this happen? A network gateway adds a port number and its own internet-compliant address to an outgoing address it gets from a computer on the network, replacing the machine’s return address. The gateway then adds a record to its translation database to make it aware that the port it utilized corresponds to a particular network device.

This technology is mostly appreciated in the corporate world because it reduces the amount of internet IP addresses an organization should have. The fact that every packet leaving the VPN gateway will have the same return address makes it a brilliant solution for VPN services to adopt. It's hard to distinguish the subscriber from which a request originated because many VPN providers have hundreds of users connecting to the same location at once.

Torrenting and NAT Firewalls

NAT firewalls can interfere with torrenting because they prevent unwanted traffic from getting to end user devices. It might be difficult to upload files to other torrent users to download. You could also find it harder to connect to as many peers from which to leech files. A NAT firewall may block you off from a sizable chunk of torrent swarm users. PAT systems work how NAT works in firewall.

That does not, however, imply that torrenting is not feasible when using a NAT firewall. Nowadays, most NAT firewalls aren’t so stringent to significantly slow down download or upload speeds. However, that might not be the case for those in public places like hotels or schools, since they tend to be more strict compared to those featured in most VPN service providers and home routers.

You can use a VPN to get around a NAT firewall on your local network if it is preventing you from torrenting. Remember that your local NAT firewall cannot tell the difference between solicited and uninvited traffic as all inbound traffic passes through the VPN and is encoded. Even while the VPN could have a NAT firewall of its own, it probably won't be as rigorous as your private networks.

More Advantages of NAT Firewalls

NAT wasn't initially designed to be a firewall. In order to avoid having to re-address every device whenever the network moved, NAT was developed to make networks more mobile. All the devices linked to it might continue using the same private IP addresses, but only the NAT device or router would need a new public facing IP address.

NAT is currently necessary for preserving the global address space. There is a finite amount of IP addresses that may be used by the IPv4 protocol, which governs how all devices on the internet connect. We would quickly run out of IP addresses if each gadget that connected to the internet needed a special address. One IPv4 address can connect several devices on a private network using a NAT gateway.

Because of the sluggish adoption of IPv6, which was created to ultimately replace IPv4 with a considerably wider address space, NAT has become an essential technology to maintain the internet's functionality.

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