tcpsso: improve man page

Describe explicitly the handling of TCP endpoints in the TIME-WAIT and
SYN-RCVD state.

Reported by:		glebius@
Reviewed by:		glebius@
Sponsored by:		Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D35651

1 files changed, 20 insertions, 7 deletions

diff --git a/usr.sbin/tcpsso/tcpsso.8 b/usr.sbin/tcpsso/tcpsso.8
index b3aee93ae5da..14402ac4daee 100644
--- a/usr.sbin/tcpsso/tcpsso.8
+++ b/usr.sbin/tcpsso/tcpsso.8
@@ -24,7 +24,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd February 10, 2022
+.Dd June 30, 2022
 .Dt TCPSSO 8
 .Os
 .Sh NAME
@@ -73,6 +73,15 @@ and value
 .Ar optval
 on a TCP endpoint from the command line.
 .Pp
+TCP endpoints in the
+.Dv TIME_WAIT
+state can not be handled by
+.Nm .
+TCP endpoints in the
+.Dv SYN_RCVD
+state can only be handled if their prior state was
+.Dv SYN_SENT .
+.Pp
 .Op Ar level
 can be specified as a non negative number or a symbolic name like
 .Dv SOL_SOCKET ,
@@ -129,8 +138,8 @@ If
 .Fl a
 is specified then
 .Nm
-will apply the socket option to all TCP endpoints not being in the state
-.Dv TIME_WAIT .
+will apply the socket option to all TCP endpoints subject to the above state
+restrictions.
 .Pp
 If
 .Fl C Ar cc-algo
@@ -139,8 +148,7 @@ is specified then
 will apply the socket option to all TCP endpoints using the TCP
 congestion control algorithm
 .Ar cc-algo
-and not being in the state
-.Dv TIME_WAIT .
+and subject to the above state restrictions.
 .Pp
 If
 .Fl S Ar stack
@@ -149,8 +157,7 @@ is specified then
 will apply the socket option to all TCP endpoints using the TCP
 stack
 .Ar stack
-and not being in the state
-.Dv TIME_WAIT .
+and subject to the above state restrictions.
 .Pp
 If
 .Fl s Ar state
@@ -170,6 +177,12 @@ is one of
 .Dv CLOSING ,
 .Dv LAST_ACK ,
 .Dv FIN_WAIT_2 .
+Using
+.Dv SYN_RCVD
+only applies to TCP endpoints in the state
+.Dv SYN_RCVD
+if their prior state was
+.Dv SYN_SENT .
 .Pp
 If multiple of
 .Fl C Ar cc-algo ,