sync code with last improvements from OpenBSD

usr.bin/ssh/ssh_config.5

@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh_config.5,v 1.383 2023/07/17 05:36:14 jsg Exp $
-.Dd $Mdocdate: July 17 2023 $
+.\" $OpenBSD: ssh_config.5,v 1.386 2023/08/28 09:52:09 djm Exp $
+.Dd $Mdocdate: August 28 2023 $
 .Dt SSH_CONFIG 5
 .Os
 .Sh NAME
@@ -1359,6 +1359,25 @@ or
 Specifies the number of password prompts before giving up.
 The argument to this keyword must be an integer.
 The default is 3.
+.It Cm ObscureKeystrokeTiming
+Specifies whether
+.Xr ssh 1
+should try to obscure inter-keystroke timings from passive observers of
+network traffic.
+If enabled, then for interactive sessions,
+.Xr ssh 1
+will send keystrokes at fixed intervals of a few tens of milliseconds
+and will send fake keystroke packets for some time after typing ceases.
+The argument to this keyword must be
+.Cm yes ,
+.Cm no
+or an interval specifier of the form
+.Cm interval:milliseconds
+(e.g.\&
+.Cm interval:80
+for 80 milliseconds).
+The default is to obscure keystrokes using a 20ms packet interval.
+Note that smaller intervals will result in higher fake keystroke packet rates.
 .It Cm PasswordAuthentication
 Specifies whether to use password authentication.
 The argument to this keyword must be