1.\" $OpenBSD: tcpdrop.8,v 1.14 2023/02/06 18:14:10 millert Exp $ 2.\" 3.\" Copyright (c) 2004 Markus Friedl <markus@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: February 6 2023 $ 18.Dt TCPDROP 8 19.Os 20.Sh NAME 21.Nm tcpdrop 22.Nd drop a TCP connection 23.Sh SYNOPSIS 24.Nm tcpdrop 25.Ar local-addr 26.Ar local-port 27.Ar remote-addr 28.Ar remote-port 29.Sh DESCRIPTION 30The 31.Nm 32command drops the TCP connection specified by the local address 33.Ar local-addr , 34port 35.Ar local-port 36and the foreign address 37.Ar remote-addr , 38port 39.Ar remote-port . 40Addresses and ports can be specified by name or numeric value. 41.Pp 42To simplify dropping TCP connections using the output of 43.Xr fstat 1 44and 45.Xr netstat 1 , 46.Nm 47also supports a two-argument form where the address and port are 48separated by a colon 49.Pq Sq \&: 50or dot 51.Pq Sq \&. 52character. 53.Sh EXAMPLES 54If a connection to 55.Xr httpd 8 56is causing congestion on a network link, one can drop the TCP session 57in charge: 58.Bd -literal -offset indent 59$ fstat | grep 'httpd.*internet.*<--' 60www httpd 21307 3* internet stream tcp \e 61 0xd1007ca8 192.168.5.41:80 <-- 192.168.5.1:26747 62.Ed 63.Pp 64Either of the following commands will drop the connection: 65.Bd -literal -offset indent 66# tcpdrop 192.168.5.41 80 192.168.5.1 26747 67 68# tcpdrop 192.168.5.41:80 192.168.5.1:26747 69 70# tcpdrop 192.168.5.41.80 192.168.5.1.26747 71.Ed 72.Sh SEE ALSO 73.Xr fstat 1 , 74.Xr netstat 1 75.Sh HISTORY 76The 77.Nm 78program first appeared in 79.Ox 3.6 . 80.Sh AUTHORS 81.An -nosplit 82The 83.Nm 84program was written by 85.An Markus Friedl Aq Mt markus@openbsd.org . 86