Corporate billing allows you to record the traffic of all devices on your local network. In a typical small business setup, a router is used to distribute the Internet to all devices in the office. There is no way to find out which device was accessed, when and which sites.
Each employee can connect any of their devices and use the corporate Internet at their own discretion, which does not add security - because the lack of control only reduces it.
We have assembled a corporate traffic accounting server based on Linux Debian 12 using free services. The traffic counting is handled by the Squid service, the access logs are analyzed by Sarg, and all routes are handled by the iptables service. The DHCP service operates to distribute IP addresses. Thus, the server performs the functions of a router with the ability to count and control access for each device on the corporate network.
You can assign each device a static local IP, which will be assigned to a predefined MAC address, which will add convenience to viewing traffic.
Iptables and Squid will allow you to add prohibited resources, which will increase the security of the corporate network and better warn against possible threats.
Detailed description of the configuration: Configuring a traffic accounting server for all devices on the local network