What is the purpose of configuring source NAT on a FortiGate device?

Configuring source NAT (Network Address Translation) on a FortiGate device serves the purpose of modifying the source IP addresses of outgoing packets. This function is particularly useful when a private network needs to access external resources while hiding its internal IP structure. By changing the source IP address, the FortiGate can map multiple local IP addresses to a single public IP address, making it easier for external servers to respond to the requests without being aware of the multiple internal devices.

This approach not only helps in maintaining security by obscuring the internal network but also allows for efficient use of the available IP address space, especially in scenarios where there is a shortage of public IPv4 addresses. Source NAT ensures that return traffic to the public address can be correctly routed back to the original requesting device on the private network.

Other options, while they may relate to networking functionalities, do not pertain directly to the specific role of source NAT. For instance, managing inbound traffic and establishing VPN connectivity involve different processes and configurations that do not focus on modifying source IP addresses. Optimizing bandwidth usage may involve Quality of Service configurations rather than NAT settings.