TCPSSO(8) FreeBSD System Manager's Manual TCPSSO(8)
NAME
tcpsso - set a socket option on a TCP endpoint
SYNOPSIS
tcpsso -i id [level] optname optval
tcpsso -a [level] optname optval
tcpsso -C cc-algo [-S stack] [-s state] [level] optname optval
tcpsso [-C cc-algo] -S stack [-s state] [level] optname optval
tcpsso [-C cc-algo] [-S stack] -s state [level] optname optval
DESCRIPTION
The tcpsso command applies a level level socket option with name optname
and value optval on a TCP endpoint from the command line.
TCP endpoints in the SYN_RCVD state can only be handled by tcpsso if
their prior state was SYN_SENT.
[level] can be specified as a non-negative number or a symbolic name like
SOL_SOCKET, IPPROTO_IP, IPPROTO_IPV6, or IPPROTO_TCP. If not specified,
tcpsso deduces the level from optname, if provided as a symbolic name.
If that is not the case, IPPROTO_TCP is used.
optname can be specified as a non-negative number or a symbolic name like
SO_DEBUG, IP_TOS, IPV6_TCLASS, TCP_LOG, TCP_CONGESTION, or
TCP_FUNCTION_BLK.
optval can be an integer value, which will be converted to a binary value
and passed as an int value. If it cannot be parsed as an integer value,
it will be processed as a string. If the optname is TCP_FUNCTION_BLK
then optval is converted to a struct tcp_function_set.
If -i id is specified then tcpsso will apply the socket option to the TCP
endpoint with the inp_gencnt provided as id. The inp_gencnt for existing
TCP endpoints can be determined by using sockstat(1).
If -a is specified then tcpsso will apply the socket option to all TCP
endpoints subject to the above state restrictions.
If -C cc-algo is specified then tcpsso will apply the socket option to
all TCP endpoints using the TCP congestion control algorithm cc-algo and
subject to the above state restrictions.
If -S stack is specified then tcpsso will apply the socket option to all
TCP endpoints using the TCP stack stack and subject to the above state
restrictions.
If -s state is specified then tcpsso will apply the socket option to all
TCP endpoints being in the state state. state is one of CLOSED, LISTEN,
SYN_SENT, SYN_RCVD, ESTABLISHED, CLOSE_WAIT, FIN_WAIT_1, CLOSING,
LAST_ACK, FIN_WAIT_2, or TIME_WAIT. Using SYN_RCVD only applies to TCP
endpoints in the state SYN_RCVD if their prior state was SYN_SENT.
If multiple of -C cc-algo, -S stack, and -s state are specified, tcpsso
will apply the socket option to all TCP endpoints using the congestion
control algorithm cc-algo, being in the state state, and using the TCP
stack stack, if specified.
If none of the -a, -C, -S, or -s options are specified then the option -i
must be specified.
EXIT STATUS
The tcpsso utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
To diagnose a problem with a particular TCP connection to sshd(8), first
determine its inp_gencnt using sockstat(1):
# sockstat -4 -c -i -p 22 -P tcp -q
root sshd 827 4 tcp4 \
192.168.1.1:22 192.168.1.2:53736 435
Then, use the following command to enable Black Box Logging on it:
# tcpsso -i 435 TCP_LOG 4
To switch all TCP endpoints from using the freebsd stack to the RACK
stack use:
# tcpsso -S freebsd TCP_FUNCTION_BLK rack
Switch all TCP endpoints in the LISTEN state to the RACK stack by using:
# tcpsso -s LISTEN TCP_FUNCTION_BLK rack
The following command will set the congestion control module of all TCP
endpoints currently using cubic as its congestion control algorithm to
the congestion control algorithm newreno:
# tcpsso -C cubic TCP_CONGESTION newreno
SEE ALSO
sockstat(1), setsockopt(2), tcp(4), tcp_functions(9)
HISTORY
The tcpsso command first appeared in FreeBSD 14.
AUTHORS
Michael Tuexen <
[email protected]>
FreeBSD 14.1-RELEASE-p8 August 3, 2024 FreeBSD 14.1-RELEASE-p8