NethServer is a CentOS-based Linux distribution for servers. The product's main feature is a modular design which makes it simple to turn the distribution into a mail server and filter, web server, groupware, firewall, web filter, IPS/IDS or VPN server. It also includes a comprehensive web-based user interface that simplifies common administration tasks and enables single-click installation of several pre-configured modules. NethServer is designed primarily for small offices and medium-size enterprises.