Every device on a business network will have an IP address, and network address translation (NAT) is there because public IPv4 addresses can become a costly resource. Look at it like this: assigning one to every workstation, phone, and access point isn’t really practical.
NAT gives devices the ability to share a single public IP. This also handles the remapping automatically so your IT team doesn’t need to do it manually. Understanding where NAT ends and your actual security stack begins is a helpful distinction, and this article covers exactly what you need to know.
Key Takeaways:
- NAT lets every device ona private network share a single public IP address
- Private IPs stay internal and reusable, while public IPs are finite, paid, and internet-facing
- Every connection is tracked in a translation table, and unsolicited inbound traffic gets dropped
- Hiding internal addressing doesn’t replace the need for NGFW inspection or a layered security strategy
- Dual-stack IPv4 and IPv6 environments keep NAT relevant for the foreseeable future
What is Network Address Translation?
Network address translation remaps private IP addresses to a public IP address before traffic leaves the network. Of course, understanding the difference between a private network and a public network helps paint the picture here.
- Private IP addresses are assigned internally by your router or firewall, for example
- Public IPs are assigned by your ISP and are visible to the internet
- Without NAT translating private addresses toa public IP, internal devices have no way to reach the internet
Moreover, I always want to note that multiple organizations can use the same private IP ranges internally. This is without conflict as well, since those addresses never appear on the public internet. To any seasoned IT team, this may seem like a no-brainer, but there are many businesses that are operating without a definitive understanding of NAT.
Expanding on the Difference Between Private Network and Public Network Addresses
Remember the easy part: private IP addresses never appear on the public internet, and public IPs come from your ISP and are visible to anyone on the outside. In addition to that, public addresses are a finite and paid resource. For a bit more context, check out the table below for a layered comparison between public and private IPs.
| Category | Private IP Address | Public IP Address |
|---|---|---|
| Assigned By | Your router, firewall, or DHCP server | Your internet service provider |
| Internet Routable | No | Yes |
| Visibility | Internal network only | Visible to the internet |
| Availability | Reusable across any network | Limited |
| NAT Requires | Yes, to reach the internet | No, routable directly |
Private and public addresses exist in completely separate spaces. NAT was designed to fill that gap, and is now a standard part of essentially every modern business network. Nowadays, a company with numerous internal devices only needs one public IP address to get all of them online.
How NAT Translates IP Addresses Inside Private Networks
Another detail I like to focus on is that NAT is a stateful process. For those who aren’t already aware, this means it keeps track of every active connection passing through. Every translation is tracked, matched, and managed in real time, so traffic always reaches the right destination.
However, NAT also determines what inbound traffic is allowed to enter your network. If something arrives without a matching entry in the translation, it gets dropped. It’s this exact behavior that plays such an important role in modern business networks and how they handle unsolicited contact.
The Translation Process, Step by Step
When an internal device sends a request to the internet, it uses its private IP address as the source. From there, the NAT device intercepts the packet and rewrites the source IP to your organization’s public IP address.
Think of the translation process like this:
- An internal device sends a request using its private IP
- The NAT device rewrites the source IP (and port) to the public IP
- A translation table logs the mapping
- Return traffic is matched against the table and forwarded to the right device
- Unsolicited inbound traffic with no table entry ends up getting dropped
Another important angle I like to focus on about NAT is how there are different types involved. Moreover, knowing how to configure each type correctly is a core part of firewall configuration as a whole.
Different Types of NAT
NAT comes in several forms, each focusing on a unique network scenario. For example, Static NAT creates a one-to-one mapping between a private IP and a fixed public IP. On the other hand, you also have Dynamic NAT, which maps internal devices to a pool of available public IPs, assigning them on demand as connections are made.
Moreover, port forwarding is a big part of this conversation as well. It routes traffic arriving on a specific inbound port to a designated internal host. This is pretty common for hosted services and things like remote access.
Where NAT Fits Among Your Cybersecurity Measures
At its core, network address translation keeps your internal IP structure hidden from the outside world. The translation table does a lot of the heavy lifting by blocking unsolicited inbound connections by default. It’s these two main characteristics of NAT that are security-adjacent benefits.
However, that shouldn’t be mistaken for the full range of security coverage your business network connections really need. It’s simply one of many important layers to the big picture. When it comes to this side of the conversation, next-gen firewall hardware helps fill in a lot of the gaps.
Choosing IP Management Solutions for Growing Business Networks
It’s equally important to maintain the focus on a layered security strategy. Never put all of your eggs in one basket when it comes to cybersecurity. While NAT is a helpful and important component of network security, it’s simply one piece of the puzzle. The list below offers a brief look into the various IP management solutions you should consider outside of network address translation alone.
- Managed firewall services are great for organizations that prefer expert-level oversight without having to manage an internal IT team
- Network switches support VLANs, which help separate departments in their own private subnets
- Centralized management is important for any multi-site business, as it gives you a consolidated view of how NAT is operating across every location
Even with advancements like IPv6, which was designed to eliminate the scarcity problem that made NAT necessary, we aren’t living in a fully IPv6 world. Many organizations are supporting both IPv4 and IPv6, meaning NAT still plays an important role here.
Let’s Wrap This Up
Network address translation lets every device on a business network share a single public IP address. It hides your internal IP structure and drops any unsolicited inbound traffic. Then again, it shouldn’t be seen as a replacement for any important layer of a business security stack.
Considering the right firewall hardware, licensing, and managed support are just a few other crucial angles every business needs to consider. That’s why our team at Firewalls.com is on standby to help you sort through the noise. All it takes is one conversation to put your business network on the right path for years to come.
Frequently Asked Questions
How do You Safely Expose Internal Services Through NAT?
Pair every port forwarding rule with strict access policies and IPS, or use ZTNA instead of open ports.
What’s the Difference Between Static and Dynamic NAT?
Static NAT maps one internal host to a fixed public IP, while dynamic NAT assigns addresses from a pool on demand.
Is NAT Enough to Secure a Business Network?
Definitely not, as NAT only hides internal addressing, so NGFWs are still a requirement for traffic inspection and threat prevention.
Why Does NAT Drop Unsolicited Inbound Traffic?
As a stateful process, NAT only forwards inbound packets that match an existing entry in its translation table.
Does IPv6 Make NAT Obsolete?
Not yet, since many companies still run dual-stack IPv4 and IPv6 environments.
