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cutter - cut tcp/ip connections

CUTTER(8) System Manager's Manual CUTTER(8)


cutter - cut tcp/ip connections


cutter ipaddress1 [ port1 [ ipaddress2 [ port2  ]  ]  ]


Cutter is an open source program that allows Linux firewall administrators to abort TCP/IP connections routed over the firewall or router on which it is run. it is not designed to work on the systems hosting the server or client using the connection, it only works on a linux firewall or router over which the connection is made, and it must be run by the root user of the firewall.


Cutter has been designed for use as a administrators tool for Linux firewalls. It's use (as is, or modified) for any other purpose is not sanctioned by the author. So - do not use this tool as a parachute, or to dry your cat, chill meat, answer your phone, drive you car, teach your kids to read or attack other people's computer systems or networks.
This software has been designed for legal and appropriate use by network security administrators and the like. It has been written as part of a larger Linux firewall project, targeting at controlling traffic from peer-to-peer software such as Kazaa, iMesh and others into and out of a private network. It is not designed as a tool for malicious use and the author in no way sanctions such use.
Users of the software should be aware that it's actions are easily detectable using a number of readily available network monitoring tools, and it makes no attempt to disguise it's actions. Malicious use of "cutter" could result in a jail sentence in a number of countries around the world.
The author is not responsible for the results of using this software or documented technique(whether in it's original form, or modified). It is provided "as is" in the hope that it will be useful, but no guarantees are made about it's use.


Cutter can be called using one of the following four syntaxes.
cutter ip-address
Cuts all connections passing through the firewall between any ports on the specified ip-address (either a "private" or "public" address) and any other hosts. This can be used to close down all incoming connections to a particular server, all outgoing connections from a particular client or all outgoing connections to a server.
cutter ip-address port
cutter 80
Cuts all connections to or from the specified ip-address/port pair. This allows the user to be a little more specific than the previous example and allows targeting of specific services on specific hosts.
cutter ip-address-1 port-1 ip-address-2
cutter 22
Cuts all connections between ip-address-2 and ip-address-1/port-1. This allows the user to cut connections between a specified "client" and a particular service on a specified host. Our example closes host's SSH connection to server
cutter ip-address-1 port-1 ip-address-2 port-2
cutter 22 32451
Cuts the specific connection between the two ip/port number pairs given.


Cutter 1.04 should be considered EXPERIMENTAL. The author is releasing a tool that works on the systems which he has access to (namely: IPCop and RedHat Linux), and he is seeking input on it's use on other systems, ideas for improvement, offers of sponsorship - etc.


This program is documented at: <>


Blars Blarson adapted the README and web page written by Chris Lowth into this man page for debian package of cutter. This man page may be distributed under the terms of the Gnu GPL version 2.
August, 2015 Debian Sid