Network security administrators sometimes need to be able to abort TCP/IP connections routed over their firewalls on demand. This would allow them to terminate connections such as SSH tunnels or VPNs left in place by employees over night, abort hacker attacks . . .
Network security administrators sometimes need to be able to abort TCP/IP connections routed over their firewalls on demand. This would allow them to terminate connections such as SSH tunnels or VPNs left in place by employees over night, abort hacker attacks when they are detected, stop high bandwidth consuming downloads - etc. There are many potential applications.

This article describes how a Linux IPTables based firewall/router can be used to send the right combination of TCP/IP packets to both ends of a connection to cause them to abort the conversation. It describes the steps required to perform this task, and introduces a new open-source utility called "cutter" that automates the process.

The use of linux systems as IP network firewalls and routers is becoming increasingly popular. The cheapness of the software and hardware combine with the flexibility and reliability of Linux's networking support to make such a solution highly attractive. It is often possible to deliver routing and fire walling facilities at a fraction of the cost associated with systems provided by industrial heavy-weights such as Cisco, Nortel and others.

The link for this article located at ChrisLowth is no longer available.