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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 com-
       mand line.

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

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

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

       If -s state is specified	then tcpdrop will attempt to drop all TCP con-
       nections	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 algorithm 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 connec-
       tions one at a time.

       If none of the -a, -C, -S, or -s	options	are specified  then  only  the
       connection   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 algo-
       rithm 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	14.3		       December	4, 2021			    TCPDROP(8)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=tcpdrop&manpath=FreeBSD+14.3-RELEASE+and+Ports>

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