NAT's core security function is hiding the internal network. This makes it much harder for attackers outside the network to directly target specific machines within the network. They only see the public IP address of the NAT device.
Essentially, NAT allows multiple devices on a local (private) network to access the internet using a single public IP address. This is commonly implemented in routers to enable multiple devices (like computers, smartphones, and IoT devices) to share one public IP address provided by an Internet Service Provider (ISP).
It works similarly with cloud providers, such as AWS, Azure, etc. Just instead of devices, we would talk about VPCs subnets. > https://docs.aws.amazon.com/vpc/latest/userguide/vpc-nat-gateway.html
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A) While NAT does prevent IP address conflicts between private networks and the public internet, this isn't its primary security benefit. The main security benefit is the hiding of internal IP addresses. Preventing conflicts is a side effect.
B) Acting as a proxy and inspecting packet content is a function of a proxy server or a deep packet inspection (DPI) firewall, not NAT. While a device could perform both NAT and proxying, they are separate functions.
D) NAT does use port address translation (PAT), which involves dynamically assigning port numbers. However, while this adds a layer of complexity for attackers, it's not the main security benefit. The primary benefit remains the masking of internal IPs.