If you are running securelevel 2, and you do not sync the clock before

switching to that securelevel, and the clock is off by more than
128ms, ntpd will attempt to correct by stepping the clock instead of
slewing it. So use -x in that case; from tholo

src/etc/rc.local

@@ -1,4 +1,4 @@
-#	$OpenBSD: rc.local,v 1.33 2001/06/05 23:01:55 naddy Exp $
+#	$OpenBSD: rc.local,v 1.34 2004/03/17 01:33:50 deraadt Exp $
 
 # site-specific startup actions, daemons, and other things which
 # can be done AFTER your system goes into securemode.  For actions
@@ -19,7 +19,11 @@ fi
 
 if [ X"${ntpd}" == X"YES" -a -x /usr/local/sbin/ntpd \
     -a -e /etc/ntp.conf ]; then
-       echo -n ' ntpd';       /usr/local/sbin/ntpd -p /var/run/ntpd.pid
+	ntpd_flags="-p /var/run/ntpd.pid"
+	if [ $securelevel -ge 1 ]; then
+		ntpd_flags="${ntpdflags} -x"
+	fi
+	echo -n ' ntpd';       /usr/local/sbin/ntpd ${ntpd_flags}
 fi
 
 if [ -x /usr/local/sbin/cfsd ]; then