1.\" $OpenBSD: tcpdrop.8,v 1.5 2004/05/24 13:57:31 jmc Exp $ 2.\" 3.\" Copyright (c) 2009 Juli Mallett <jmallett@FreeBSD.org> 4.\" Copyright (c) 2004 Markus Friedl <markus@openbsd.org> 5.\" 6.\" Permission to use, copy, modify, and distribute this software for any 7.\" purpose with or without fee is hereby granted, provided that the above 8.\" copyright notice and this permission notice appear in all copies. 9.\" 10.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17.\" 18.Dd July 26, 2015 19.Dt TCPDROP 8 20.Os 21.Sh NAME 22.Nm tcpdrop 23.Nd drop TCP connections 24.Sh SYNOPSIS 25.Nm 26.Ar local-address 27.Ar local-port 28.Ar foreign-address 29.Ar foreign-port 30.Nm 31.Op Fl l 32.Fl a 33.Sh DESCRIPTION 34The 35.Nm 36command may be used to drop TCP connections from the command line. 37.Pp 38If 39.Fl a 40is specified then 41.Nm 42will attempt to drop all active connections. 43The 44.Fl l 45flag may be given to list the tcpdrop invocation to drop all active 46connections one at a time. 47.Pp 48If 49.Fl a 50is not specified then only the connection between the given local 51address 52.Ar local-address , 53port 54.Ar local-port , 55and the foreign address 56.Ar foreign-address , 57port 58.Ar foreign-port , 59will be dropped. 60.Pp 61Addresses and ports may be specified by name or numeric value. 62Both IPv4 and IPv6 address formats are supported. 63.Pp 64The addresses and ports may be separated by periods or colons 65instead of spaces. 66.Sh EXIT STATUS 67.Ex -std 68.Sh EXAMPLES 69If a connection to 70.Xr httpd 8 71is causing congestion on a network link, one can drop the TCP session 72in charge: 73.Bd -literal -offset indent 74# sockstat -c | grep httpd 75www httpd 16525 3 tcp4 \e 76 192.168.5.41:80 192.168.5.1:26747 77.Ed 78.Pp 79The following command will drop the connection: 80.Bd -literal -offset indent 81# tcpdrop 192.168.5.41 80 192.168.5.1 26747 82.Ed 83.Pp 84The following command will drop all connections but those to or from 85port 22, the port used by 86.Xr sshd 8 : 87.Bd -literal -offset indent 88# tcpdrop -l -a | grep -vw 22 | sh 89.Ed 90.Sh SEE ALSO 91.Xr netstat 1 , 92.Xr sockstat 1 93.Sh AUTHORS 94.An Markus Friedl Aq Mt markus@openbsd.org 95.An Juli Mallett Aq Mt jmallett@FreeBSD.org 96