diff -Naru arpwatch-2.1a15.orig/arpwatch.c arpwatch-2.1a15/arpwatch.c
--- arpwatch-2.1a15.orig/arpwatch.c	2006-09-23 22:20:51.000000000 +0400
+++ arpwatch-2.1a15/arpwatch.c	2006-09-23 22:24:49.000000000 +0400
@@ -179,6 +179,8 @@
 	struct bpf_program code;
 	char errbuf[PCAP_ERRBUF_SIZE];
 	char* username = NULL;
+	int restart = 0;
+	int restarting_loop = 0;
 	char options[] =
 		"d"
 		"f:"
@@ -191,6 +193,7 @@
 		"p"
 		"a"
 		"u:"
+		"R:"
 		"Q"
 		"z:"
 	;
@@ -267,6 +270,10 @@
 			username = optarg;
 			break;
 
+		case 'R':
+			restart = atoi(optarg);
+			break;
+
 		case 'Q':
 			++quiet;
 			break;
@@ -285,6 +292,12 @@
 	if (optind != argc)
 		usage();
 
+	if ( username && restart ) {
+		syslog(LOG_ERR, "Please, specify either -u or -R");		
+		(void)fprintf(stderr,"Please, specify either -u or -R. See arpwatch.8\n");
+		exit(1);
+	}
+
 	if (rfilename != NULL) {
 		net = 0;
 		netmask = 0;
@@ -334,6 +347,7 @@
 		syslog(LOG_ERR, "(using current working directory)");
 	}
 
+label_restart:
 	if (rfilename != NULL) {
 		pd = pcap_open_offline(rfilename, errbuf);
 		if (pd == NULL) {
@@ -348,22 +362,30 @@
 		pd = pcap_open_live(interface, snaplen, !nopromisc, timeout, errbuf);
 		if (pd == NULL) {
 			syslog(LOG_ERR, "pcap open %s: %s", interface, errbuf);
-			exit(1);
+			if (restart) {
+				syslog(LOG_ERR, "restart in %d secs", restart);
+			} else {
+				exit(1);
+			}
+			sleep(restart);
+			goto label_restart;
 		}
 #ifdef WORDS_BIGENDIAN
 		swapped = 1;
 #endif
 	}
 
-	if ( username ) {
-		dropprivileges( username );
-	} else {
-	/*
-	 * Revert to non-privileged user after opening sockets
-	 * (not needed on most systems).
-	 */
-		setgid(getgid());
-		setuid(getuid());
+	if (!restarting_loop) {
+		if ( username && !restart ) {
+			dropprivileges( username );
+		} else {
+			/*
+			 * Revert to non-privileged user after opening sockets
+			 * (not needed on most systems).
+			 */
+			setgid(getgid());
+			setuid(getuid());
+		}
 	}
 
 	/* Must be ethernet or fddi */
@@ -386,26 +408,30 @@
 	if (rfilename == NULL)
 		syslog(LOG_INFO, "listening on %s", interface);
 
-	/* Read in database */
-	initializing = 1;
-	if (!readdata())
-		exit(1);
-	sorteinfo();
+	if (!restarting_loop) {
+		/* Read in database */
+		initializing = 1;
+		if (!readdata())
+			exit(1);
+		sorteinfo();
+	}
 #ifdef DEBUG
 	if (debug > 2) {
 		debugdump();
 		exit(0);
 	}
 #endif
-	initializing = 0;
+	if (!restarting_loop) {
+		initializing = 0;
 
-	(void)setsignal(SIGINT, die);
-	(void)setsignal(SIGTERM, die);
-	(void)setsignal(SIGHUP, die);
-	if (rfilename == NULL) {
-		(void)setsignal(SIGQUIT, checkpoint);
-		(void)setsignal(SIGALRM, checkpoint);
-		(void)alarm(CHECKPOINT);
+		(void)setsignal(SIGINT, die);
+		(void)setsignal(SIGTERM, die);
+		(void)setsignal(SIGHUP, die);
+		if (rfilename == NULL) {
+			(void)setsignal(SIGQUIT, checkpoint);
+			(void)setsignal(SIGALRM, checkpoint);
+			(void)alarm(CHECKPOINT);
+		}
 	}
 
 	switch (linktype) {
@@ -424,7 +450,15 @@
 	}
 	if (status < 0) {
 		syslog(LOG_ERR, "pcap_loop: %s", pcap_geterr(pd));
-		exit(1);
+		if (restart && rfilename == NULL) {
+			syslog(LOG_ERR, "restart in %d secs", restart);
+			++restarting_loop;
+			pcap_close(pd);
+		} else {
+			exit(1);
+		}
+		sleep(restart);
+		goto label_restart;
 	}
 	pcap_close(pd);
 	if (!dump())
@@ -851,6 +885,7 @@
 		"[-p] "
 		"[-a] "
 		"[-u username] "
+		"[-R seconds ] "
 		"[-Q ] "
 		"[-z ignorenet/ignoremask] "
 		"\n"