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>> How do you flush the ARP tables???
>
>Presuming a Bourne-derived shell:
>
># for i in `arp -a | awk '{ print $1 }'`; do arp -d ${i} ; done
>
>(Yes, arp really ought to have a flush. No, it doesn't seem to. Note
>the hash above. Yes, you must be root to use arp -d.)

# arp -na | awk '{gsub("[()]","",$2);print$2}' | xargs -n1 arp -vd

for something less shell-centric.

for arp(8), i add the -D option with the attached patch.  anyone mind
if it gets committed?

(-D because -f is already taken)

-- 
|-----< "CODE WARRIOR" >-----|
codewarrior@daemon.org             * "ah!  i see you have the internet
twofsonet@graffiti.com (Andrew Brown)                that goes *ping*!"
andrew@crossbar.com       * "information is power -- share the wealth."

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Index: arp.8
===================================================================
RCS file: /cvsroot/basesrc/usr.sbin/arp/arp.8,v
retrieving revision 1.11
diff -u -r1.11 arp.8
--- arp.8	1999/03/22 18:43:48	1.11
+++ arp.8	2001/04/13 19:32:49
@@ -50,6 +50,9 @@
 .Op Fl v
 .Fl d Ar hostname
 .Nm ""
+.Op Fl v
+.Fl D
+.Nm ""
 .Fl s Ar hostname ether_addr
 .Op Ar temp
 .Op Ar pub
@@ -80,6 +83,8 @@
 with the
 .Fl d
 flag.
+.It Fl D
+A super-user may delete all entries from the arp table.
 .It Fl n
 Show network addresses as numbers (normally
 .Nm
Index: arp.c
===================================================================
RCS file: /cvsroot/basesrc/usr.sbin/arp/arp.c,v
retrieving revision 1.29
diff -u -r1.29 arp.c
--- arp.c	2001/03/19 19:49:30	1.29
+++ arp.c	2001/04/13 19:32:50
@@ -85,6 +85,7 @@
 
 int	delete __P((const char *, const char *));
 void	dump __P((u_long));
+void	delete_all __P((void));
 void	sdl_print __P((const struct sockaddr_dl *));
 int	getifname __P((u_int16_t, char *));
 int	atosdl __P((const char *s, struct sockaddr_dl *sdl));
@@ -117,12 +118,13 @@
 	pid = getpid();
 	progname = ((progname = strrchr(argv[0], '/')) ? progname + 1 : argv[0]);
 
-	while ((ch = getopt(argc, argv, "andsfv")) != -1)
+	while ((ch = getopt(argc, argv, "andsfvD")) != -1)
 		switch((char)ch) {
 		case 'a':
 		case 'd':
 		case 's':
 		case 'f':
+		case 'D':
 			if (op)
 				usage();
 			op = ch;
@@ -156,6 +158,11 @@
 		if (argc != 1)
 			usage();
 		return (file(argv[0]));
+	case 'D':
+		if (argc != 0)
+			usage();
+		delete_all();
+		break;
 	default:
 		if (argc != 1)
 			usage();
@@ -455,6 +462,45 @@
 				(void)printf("(weird)");
 		}
 		(void)printf("\n");
+	}
+}
+
+/*
+ * Delete the entire arp table
+ */
+void
+delete_all(void)
+{
+	int mib[6];
+	size_t needed;
+	char addr[sizeof("000.000.000.000\0")];
+	char *lim, *buf, *next;
+	struct rt_msghdr *rtm;
+	struct sockaddr_inarp *sin;
+	struct sockaddr_dl *sdl;
+
+	mib[0] = CTL_NET;
+	mib[1] = PF_ROUTE;
+	mib[2] = 0;
+	mib[3] = AF_INET;
+	mib[4] = NET_RT_FLAGS;
+	mib[5] = RTF_LLINFO;
+	if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
+		err(1, "route-sysctl-estimate");
+	if (needed == 0)
+		return;
+	if ((buf = malloc(needed)) == NULL)
+		err(1, "malloc");
+	if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
+		err(1, "actual retrieval of routing table");
+	lim = buf + needed;
+	for (next = buf; next < lim; next += rtm->rtm_msglen) {
+		rtm = (struct rt_msghdr *)next;
+		sin = (struct sockaddr_inarp *)(rtm + 1);
+		sdl = (struct sockaddr_dl *)
+		    (ROUNDUP(sin->sin_len) + (char *)sin);
+		snprintf(addr, sizeof(addr), "%s", inet_ntoa(sin->sin_addr));
+		delete(addr, NULL);
 	}
 }
 

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