There are occasions during an administrator's work when it is necessary to forcibly disconnect an established TCP session. However, no easy way exists for an administrator to drop an established TCP session without doing something heavy-handed, such as null routing all traffic from the client, adding an ipfilter rule (which, again, likely blocks more traffic than is strictly necessary), or taking the last resort of killing the associated server-side process.

Ceri Davies ported tcpdrop from the BSD projects, which allows an administrator to easily drop any TCP connection without harmful effects elsewhere.

The Carnegie Mellon NetReg package is a scalable and flexible Web-based system for managing networks. It consolidates information about DNS zones, subnets, machine registrations, and DHCP configuration, and provides tools for easy management. The system exports ISC BIND configuration and zones, and can update them via either static zone files or TSIG signed dynamic DNS updates. It also exports ISC DHCP configurations, and has a SOAP API for integration with other systems.

Nmap is a powerful tool for discovering hosts on a network and enumerating what service they are offering. This can be used to find vulnerable systems, to locate rogue services on your network or simply for a first step in troubleshooting.