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

NAME
     tcpdrop -- drop TCP connections

SYNOPSIS
     tcpdrop local-address local-port foreign-address foreign-port
     tcpdrop [-l] -a
     tcpdrop [-l] -C cc-algo [-S stack] [-s state]
     tcpdrop [-l] [-C cc-algo] -S stack [-s state]
     tcpdrop [-l] [-C cc-algo] [-S stack] -s state

DESCRIPTION
     The  tcpdrop  command  may be used to drop TCP connections from the command
     line.

     If -a is specified then tcpdrop will attempt to drop all TCP connections.

     If -C cc-algo is specified then tcpdrop will attempt to  drop  all  connec-
     tions using the TCP congestion control algorithm cc-algo.

     If  -S stack is specified then tcpdrop will attempt to drop all connections
     using the TCP stack stack.

     If -s state is specified then tcpdrop will attempt to drop all TCP  connec-
     tions  being  in  the  state  state.   state  is one of SYN_SENT, SYN_RCVD,
     ESTABLISHED, CLOSE_WAIT,  FIN_WAIT_1,  CLOSING,  LAST_ACK,  FIN_WAIT_2,  or
     TIME_WAIT.

     If  multiple  of  -C cc-algo, -S stack, and -s state are specified, tcpdrop
     will attempt to drop all TCP connections using the congestion control algo-
     rithm cc-algo, being in the state state, and using the TCP stack stack,  if
     specified.   Since  TCP  connections in the TIME_WAIT state are not tied to
     any TCP stack, using the option -s TIME_WAIT in  combination  with  the  -S
     stack option results in tcpdrop not dropping any TCP connection.

     The  -l  flag  may be given in addition to the -a, -C, -S, or -s options to
     list the tcpdrop invocation to drop all corresponding TCP	connections  one
     at a time.

     If  none  of the -a, -C, -S, or -s options are specified then only the con-
     nection between the given local address local-address, port local-port, and
     the foreign address foreign-address, port foreign-port, will be dropped.

     Addresses and ports may be specified by name or numeric value.   Both  IPv4
     and IPv6 address formats are supported.

     The  addresses  and  ports may be separated by periods or colons instead of
     spaces.

EXIT STATUS
     The tcpdrop utility exits 0 on success, and >0 if an error occurs.

EXAMPLES
     If a connection to httpd(8) is causing congestion on a  network  link,  one
     can drop the TCP session in charge:

	   # sockstat -c | grep httpd
	   www	    httpd      16525 3	tcp4 \
		   192.168.5.41:80	192.168.5.1:26747

     The following command will drop the connection:

	   # tcpdrop 192.168.5.41 80 192.168.5.1 26747

     The  following  command will drop all connections but those to or from port
     22, the port used by sshd(8):

	   # tcpdrop -l -a | grep -vw 22 | sh

     To drop all TCP connections using the new-reno congestion control algorithm
     use:

	   # tcpdrop -C new-reno

     The following command will drop all connections using the TCP stack rack:

	   # tcpdrop -S rack

     To drop all TCP connections in the LAST_ACK state use:

	   # tcpdrop -s LAST_ACK

     To drop all TCP connections using the congestion control algorithm new-reno
     and the TCP stack rack and being in the LAST_ACK state use:

	   # tcpdrop -C new-reno -S rack -s LAST_ACK

SEE ALSO
     netstat(1), sockstat(1), tcp(4), tcp_functions(9)

AUTHORS
     Markus Friedl <markus@openbsd.org>
     Juli Mallett <jmallett@FreeBSD.org>

FreeBSD ports 15.1		December 4, 2021		      TCPDROP(8)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=tcpdrop&sektion=8&manpath=FreeBSD+15.1-RELEASE+and+Ports>

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