--- resources/OCF/IPaddr.orig	2009-08-06 13:08:35.000000000 +0200
+++ resources/OCF/IPaddr	2009-08-06 13:12:35.000000000 +0200
@@ -298,9 +298,56 @@
   return $OCF_ERR_GENERIC
 }
 
+#
+#      Find out which alias serves the given IP address
+#      The argument is an IP address, and its output
+#      is an interface name (e.g., "em0").
+#
+#      parse the output of ifconfig and find the interface
+#      that holds ip address $ip (multiple may exist, but
+#      only one with flag UP)
+#      Try to find an interface with flag UP. If we don't find
+#      such an interface, try to find one with flag DOWN
+
 find_interface_bsd() {
-    #$IFCONFIG $IFCONFIG_A_OPT | grep "inet.*[: ]$OCF_RESKEY_ip "
-    $IFCONFIG | grep "$ipaddr" -B20 | grep "UP," | tail -n 1 | cut -d ":" -f 1
+
+    ipaddr="$1";
+
+    /sbin/ifconfig \
+       | /usr/bin/perl -w -e '
+
+            my $ip = $ARGV[0];
+
+            if (! $ip) {
+                exit(255);
+            }
+
+            my $if_name = "";
+            my $if_status = 0;
+
+            my $down_if_name = "";
+
+            while (<STDIN>) {
+                chomp();
+                if ( /^(\w+):\s+flags=/ ) {
+                    $if_name = $1;
+                    $if_status = ( /UP/ ) ? 1 : 0;
+                }
+                if ( /^\s+inet\s+${ip}/ ) {
+                    if ( $if_status ) {
+                        print $if_name;
+                        exit(0)
+                    } else {
+                        $down_if_name = $if_name;
+                    }
+                }
+            }
+
+            if ($down_if_name) {
+                print $down_if_name;
+            }
+
+         ' $ipaddr
 }
 
 #