diff -uNr nagios-plugins-1.4.3.old/plugins/check_ping.c nagios-plugins-1.4.3/plugins/check_ping.c
--- nagios-plugins-1.4.3.old/plugins/check_ping.c	2006-03-13 06:08:28.000000000 -0500
+++ nagios-plugins-1.4.3/plugins/check_ping.c	2006-05-19 11:33:42.000000000 -0400
@@ -50,6 +50,7 @@
 float wrta = UNKNOWN_TRIP_TIME;
 float crta = UNKNOWN_TRIP_TIME;
 char **addresses = NULL;
+char *source_address;
 int n_addresses = 0;
 int max_addr = 1;
 int max_packets = -1;
@@ -67,6 +68,7 @@
 {
 	char *cmd = NULL;
 	char *rawcmd = NULL;
+	char *ping_args = NULL;
 	int result = STATE_UNKNOWN;
 	int this_result = STATE_UNKNOWN;
 	int i;
@@ -101,15 +103,28 @@
 		rawcmd = strdup(PING_COMMAND);
 #endif
 
+		ping_args = strdup("");
+
+		/* Need to check ping -I in configure and enclose this in ifdef */
+		if (source_address != NULL) {
+			ping_args = realloc (ping_args, 20 * sizeof(char));
+			ping_args = strcat(ping_args, "-I ");
+			ping_args = strncat(ping_args, source_address, 15 * sizeof(char));
+			ping_args = strcat(ping_args, " ");
+		}
+
+		ping_args = realloc (ping_args, strlen(ping_args) + strlen(addresses[i]) + 1);
+		ping_args = strcat(ping_args, addresses[i]);
+
 		/* does the host address of number of packets argument come first? */
 #ifdef PING_PACKETS_FIRST
 # ifdef PING_HAS_TIMEOUT
-		asprintf (&cmd, rawcmd, timeout_interval, max_packets, addresses[i]);
+		asprintf (&cmd, rawcmd, timeout_interval, max_packets, ping_args);
 # else
-		asprintf (&cmd, rawcmd, max_packets, addresses[i]);
+		asprintf (&cmd, rawcmd, max_packets, ping_args);
 # endif
 #else
-		asprintf (&cmd, rawcmd, addresses[i], max_packets);
+		asprintf (&cmd, rawcmd, ping_args, max_packets);
 #endif
 
 		if (verbose >= 2)
@@ -150,6 +165,7 @@
 			printf ("%f:%d%% %f:%d%%\n", wrta, wpl, crta, cpl);
 
 		result = max_state (result, this_result);
+		free (ping_args);
 		free (rawcmd);
 		free (cmd);
 	}
@@ -170,6 +186,7 @@
 	static struct option longopts[] = {
 		STD_LONG_OPTS,
 		{"packets", required_argument, 0, 'p'},
+		{"source", required_argument, 0, 's'},
 		{"nohtml", no_argument, 0, 'n'},
 		{"link", no_argument, 0, 'L'},
 		{"use-ipv4", no_argument, 0, '4'},
@@ -188,7 +205,7 @@
 	}
 
 	while (1) {
-		c = getopt_long (argc, argv, "VvhnL46t:c:w:H:p:", longopts, &option);
+		c = getopt_long (argc, argv, "VvhnL46t:c:w:H:p:s:", longopts, &option);
 
 		if (c == -1 || c == EOF)
 			break;
@@ -245,6 +262,9 @@
 			else
 				usage2 (_("<max_packets> (%s) must be a non-negative number\n"), optarg);
 			break;
+		case 's':	/* number of packets to send */
+			source_address = strdup (optarg);
+			break;
 		case 'n':	/* no HTML */
 			display_html = FALSE;
 			break;
@@ -396,6 +416,11 @@
 		usage (_("You must specify a server address or host name"));
 	}
 
+	if (source_address != NULL) {
+		if (is_addr(source_address) == FALSE)
+			usage2 (_("Invalid source address"), source_address);
+	}
+
 	return OK;
 }
 
@@ -535,6 +560,8 @@
    critical threshold pair\n\
 -p, --packets=INTEGER\n\
    number of ICMP ECHO packets to send (Default: %d)\n\
+-s, --source=IP\n\
+   source address\n\
 -L, --link\n\
    show HTML in the plugin output (obsoleted by urlize)\n"),
 	        DEFAULT_MAX_PACKETS);
@@ -559,5 +586,5 @@
 print_usage (void)
 {
 	printf ("Usage: %s -H <host_address> -w <wrta>,<wpl>%% -c <crta>,<cpl>%%\n\
-                     [-p packets] [-t timeout] [-L] [-4|-6]\n", progname);
+                     [-p packets] [-s source_address] [-t timeout] [-L] [-4|-6]\n", progname);
 }