--- ping.c.orig	Fri Jun 30 00:16:47 2000
+++ ping.c	Thu Jun 29 22:13:18 2000
@@ -79,6 +79,7 @@
 #include <stdio.h>
 #include <ctype.h>
 #include <errno.h>
+#include <math.h>
 
 /*
  * Note: on some systems dropping root makes the process dumpable or
@@ -151,6 +152,7 @@
 #define	F_SO_DEBUG	0x040
 #define	F_SO_DONTROUTE	0x080
 #define	F_VERBOSE	0x100
+#define F_STD_DEV	0x200
 
 /* multicast options */
 int moptions;
@@ -197,6 +199,9 @@
 static u_long tmax = 0;		/* maximum round trip time */
 static u_long tsum;		/* sum of all times, for doing average */
 
+/* sum of the squares of the times, for doing standard deviations */
+static u_long tsumsquared = 0; 
+
 /* protos */
 static char *pr_addr(u_long);
 static int in_cksum(u_short *addr, int len);
@@ -254,7 +259,7 @@
 
 	preload = 0;
 	datap = &outpack[8 + sizeof(struct timeval)];
-	while ((ch = getopt(argc, argv, "I:LRc:dfh:i:l:np:qrs:t:v")) != EOF)
+	while ((ch = getopt(argc, argv, "I:LRSc:dfh:i:l:np:qrs:t:v")) != EOF)
 		switch(ch) {
 		case 'c':
 			npackets = atoi(optarg);
@@ -339,6 +344,9 @@
 			moptions |= MULTICAST_NOLOOP;
 			loop = 0;
 			break;
+		case 'S':
+			options |= F_STD_DEV;
+			break;
 		case 't':
 			moptions |= MULTICAST_TTL;
 			i = atoi(optarg);
@@ -727,6 +735,7 @@
 			tvsub(&tv, tp);
 			triptime = tv.tv_sec * 10000 + (tv.tv_usec / 100);
 			tsum += triptime;
+			tsumsquared += triptime * triptime;
 			if (triptime < tmin && !negflag)
 				tmin = triptime;
 			if (triptime > tmax && !negflag)
@@ -933,6 +942,10 @@
 static void
 finish(int ignore)
 {
+	u_long count;
+	u_long mean;
+	u_long deviation;
+
 	(void)ignore;
 
 	(void)signal(SIGINT, SIG_IGN);
@@ -957,6 +970,16 @@
 			(tsum / (nreceived + nrepeats))/10,
 			(tsum / (nreceived + nrepeats))%10,
 			tmax/10, tmax%10);
+
+	if (nreceived && timing && (options & F_STD_DEV)) {
+		/* Note: timing is in 100's of microseconds. */
+		count = nreceived + nrepeats;
+		if( count > 1 ) {
+			mean = tsum / count;
+			deviation = sqrt( ((tsumsquared - count*mean*mean) / (count - 1))*1.0 );
+			(void)printf("round-trip deviation = %lu.%lu ms\n", deviation/10, deviation%10 );
+		}
+	}
 
 	if (nreceived==0) exit(1);
 	exit(0);
--- Makefile.orig	Thu Jun 29 22:16:17 2000
+++ Makefile	Thu Jun 29 21:58:34 2000
@@ -13,7 +13,7 @@
 	$(CC) $(LDFLAGS) $^ $(LIBS) -o $@
 
 install: ping
-	install -o root -g root -m$(SUIDMODE) ping $(INSTALLROOT)$(ROOTBINDIR)
+	install -o root -g root -m$(SUIDMODE) ping $(INSTALLROOT)$(ROOTBINDIR) -lmath
 	install -m$(MANMODE) ping.8 $(INSTALLROOT)$(MANDIR)/man8
 
 clean: