iputils/iputils-20101006-eth.patch

--- iputils-s20121112/arping.c.orig	2012-11-13 12:12:51.000000000 +0100
+++ iputils-s20121112/arping.c	2012-11-13 12:15:11.514261164 +0100
@@ -50,7 +50,7 @@
 static void usage(void) __attribute__((noreturn));
 
 int quit_on_reply=0;
-char *device="eth0";
+char *device=NULL;
 int ifindex;
 char *source;
 struct in_addr src, dst;
@@ -71,6 +71,10 @@ struct timeval start, last;
 int sent, brd_sent;
 int received, brd_recv, req_recv;
 
+#define PREF_ETH "eth"
+#define PREF_EM  "em"
+static char *dev_file = "/proc/self/net/dev";
+
 #ifndef CAPABILITIES
 static uid_t euid;
 #endif
@@ -524,6 +528,46 @@ static void set_device_broadcast(char *d
 	return;
 }
 
+/*
+ * get_first_ethernet - return the name of the first ethernet-style
+ * interface on this system.
+ */
+char * get_first_ethernet(void)
+{
+	FILE *f;
+	char buf[255], *dv, *smc;
+	char pci[16];
+
+	memset(pci, 0, sizeof(pci));
+	if ((f = fopen(dev_file, "r")) != NULL)
+	{
+		// go through network dev file
+		while (fgets (buf, sizeof(buf), f) != NULL)
+		{
+			// the line describes interface
+			if ((smc = strchr(buf, ':')) != NULL)
+			{
+				// trim white characters
+				for (dv=buf, *smc=0; *dv <= ' '; dv++) ;
+				// is "eth" (originial ethernet name) or "em" (ethernet on board)
+				if (!strncmp(dv, PREF_ETH, strlen(PREF_ETH)) ||
+					!strncmp(dv, PREF_EM, strlen(PREF_EM)))
+				{
+					return strdup(dv);
+				}
+				// remember the first pci NIC-card
+				if (strlen(pci) == 0 && dv[0] == 'p' && isdigit(dv[1]))
+				{
+					strcpy(pci, dv);
+				}
+			}
+		}
+		fclose(f);
+	}
+	// return pci NIC-card or nil if no if name
+	return strlen(pci) > 0 ? strdup(pci) : 0L;
+}
+
 int
 main(int argc, char **argv)
 {
@@ -543,6 +587,8 @@ main(int argc, char **argv)
 
 	disable_capability_raw();
 
+	device = get_first_ethernet();
+
 	while ((ch = getopt(argc, argv, "h?bfDUAqc:w:s:I:V")) != EOF) {
 		switch(ch) {
 		case 'b':
@@ -569,6 +615,10 @@ main(int argc, char **argv)
 			timeout = atoi(optarg);
 			break;
 		case 'I':
+			if (device) {
+				free(device);
+				device = NULL;
+			}
 			device = strdup(optarg);
 			break;
 		case 'f':