diff --git a/heartbeat/findif.sh b/heartbeat/findif.sh
index cc8b853e0..a7554b48b 100644
--- a/heartbeat/findif.sh
+++ b/heartbeat/findif.sh
@@ -1,210 +1,195 @@
 #!/bin/sh
 ipcheck_ipv4() {
-  local ip=$1
-  echo "$ip" | grep -qs '^[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}$'
-  if [ $? -ne 0 ] ; then
-    return 1
-  fi
-  echo "$ip" | awk -F. '{if(NF!=4)exit(1);for(i=1;i<=4;i++)if(!($i>=0&&$i<=255))exit(1)}'
+  local r1_to_255="([1-9][0-9]?|1[0-9][0-9]|2[0-4][0-9]|25[0-5])"
+  local r0_to_255="([0-9][0-9]?|1[0-9][0-9]|2[0-4][0-9]|25[0-5])"
+  local r_ipv4="^$r1_to_255\.$r0_to_255\.$r0_to_255\.$r0_to_255$"
+  echo "$1" | grep -q -Ee "$r_ipv4"
 }
 ipcheck_ipv6() {
-  local ipaddr=$1
-  echo "$ipaddr" | grep -qs "[^0-9:a-fA-F]"
-  if [ $? = 1 ] ; then
-    return 0
-  else
-    return 1
-  fi
+  ! echo "$1" | grep -qs "[^0-9:a-fA-F]"
 }
 ifcheck_ipv4() {
   local ifcheck=$1
-  local ifstr
-  local counter=0
   local procfile="/proc/net/dev"
-  while read LINE
-  do
-    if [ $counter -ge 2 ] ; then
-      ifstr=`echo $LINE | cut -d ':' -f 1`
-      if [ "$ifstr" = "$ifcheck" ] ; then
-        return 0
-      fi
-    fi
-    counter=`expr $counter + 1`
+  local ifstr rest
+
+  while read ifstr rest ; do
+    # Interface name may be concatenated to Receive field with ':'
+    case "$ifstr" in
+      "$ifcheck:"*) return 0;;
+    esac
   done < $procfile
   return 1
 }
 ifcheck_ipv6() {
   local ifcheck="$1"
-  local ifstr
   local procfile="/proc/net/if_inet6"
-  while read LINE
-  do
-    ifstr=`echo $LINE | awk -F ' ' '{print $6}'`
-    if [ "$ifstr" = "$ifcheck" ] ; then
-      return 0
-    fi
+  local tmp ifstr
+
+  while read tmp tmp tmp tmp tmp ifstr ; do
+    [ "$ifstr" = "$ifcheck" ] && return 0
   done < $procfile
   return 1
 }
 prefixcheck() {
   local prefix=$1
   local prefix_length=${#prefix}
   local prefix_check=$2
 
   if [ $prefix_length -gt 3 -o $prefix_length -eq 0 ] ; then
     return 1
   fi
   echo "$prefix" | grep -qs "[^0-9]"
   if [ $? = 0 ] ; then
     return 1
   fi
   if [ $prefix -lt 1 -o $prefix -gt $prefix_check ] ; then
     return 1
   fi
   return 0
 }
 getnetworkinfo()
 {
   ip -o -f inet route list match $OCF_RESKEY_ip table local scope host | (while read LINE;
   do
     IP=`echo $LINE | awk '{print $2}'`
     case $IP in
     */*)
       set -- $LINE
       break
       ;;
     esac
   done
   echo $LINE)
 }
 
 findif_check_params()
 {
   local family="$1"
   local match="$OCF_RESKEY_ip"
   local NIC="$OCF_RESKEY_nic"
   local NETMASK="$OCF_RESKEY_cidr_netmask"
   local BRDCAST="$OCF_RESKEY_broadcast"
 
   if [ "$family" = "inet6" ] ; then
     ipcheck_ipv6 $match
     if [ $? = 1 ] ; then
       ocf_log err "IP address [$match] not valid."
       return $OCF_ERR_CONFIGURED
     fi
     if [ -n "$NIC" ] ; then
       ifcheck_ipv6 $NIC
       if [ $? = 1 ] ; then
         ocf_log err "Unknown interface [$NIC] No such device."
         return $OCF_ERR_CONFIGURED
       fi
     else
       echo $match | grep -qis '^fe80::'
       if [ $? = 0 ] ; then
         ocf_log err "'nic' parameter is mandatory for a link local address [$match]."
         return $OCF_ERR_CONFIGURED
       fi
     fi
     if [ -n "$NETMASK" ] ; then
       prefixcheck $NETMASK 128
       if [ $? = 1 ] ; then
         ocf_log err "Invalid netmask specification [$NETMASK]."
         return $OCF_ERR_CONFIGURED
       fi
     fi
   else
     # family = inet
     ipcheck_ipv4 $match
     if [ $? = 1 ] ; then
       ocf_log err "IP address [$match] not valid."
       return $OCF_ERR_CONFIGURED
     fi
     if [ -n "$NIC" ] ; then
       ifcheck_ipv4 $NIC
       if [ $? = 1 ] ; then
         ocf_log err "Unknown interface [$NIC] No such device."
         return $OCF_ERR_CONFIGURED
       fi
     fi
     if [ -n "$NETMASK" ] ; then
       prefixcheck $NETMASK 32
       if [ $? = 1 ] ; then
         ocf_log err "Invalid netmask specification [$NETMASK]."
         return $OCF_ERR_CONFIGURED
       fi
     fi
     if [ -n "$BRDCAST" ] ; then
       ipcheck_ipv4 $BRDCAST
       if [ $? = 1 ] ; then
         ocf_log err "Invalid broadcast address [$BRDCAST]."
         return $OCF_ERR_CONFIGURED
       fi
     fi
   fi
   return $OCF_SUCCESS
 }
 
 findif()
 {
   local match="$OCF_RESKEY_ip"
   local family
   local scope
   local NIC="$OCF_RESKEY_nic"
   local NETMASK="$OCF_RESKEY_cidr_netmask"
   local BRDCAST="$OCF_RESKEY_broadcast"
 
   echo $match | grep -qs ":"
   if [ $? = 0 ] ; then
     family="inet6"
   else
     family="inet"
     scope="scope link"
   fi
   findif_check_params $family || return $?
 
   if [ -n "$NETMASK" ] ; then
       match=$match/$NETMASK
   fi
   if [ -n "$NIC" ] ; then
     # NIC supports more than two.
     set -- `ip -o -f $family route list match $match $scope | grep "dev $NIC"`
   else
     set -- `ip -o -f $family route list match $match $scope`
   fi
   if [ $# = 0 ] ; then
     case $OCF_RESKEY_ip in
     127.*)
       set -- `getnetworkinfo`
       shift;;
     esac
   fi
   if [ -z "$NIC" -o -z "$NETMASK" ] ; then
     if [ $# = 0 ] ; then
       ocf_log err "Unable to find nic or netmask."
       return $OCF_ERR_GENERIC
     fi
     case $1 in
     */*) : OK ;;
     *)
       ocf_log err "Unable to find cidr_netmask."
       return $OCF_ERR_GENERIC ;;
     esac
   fi
   [ -z "$NIC" ] && NIC=$3
   [ -z "$NETMASK" ] && NETMASK=${1#*/}
   if [ $family = "inet" ] ; then
     if [ -z "$BRDCAST" ] ; then
       if [ -n "$7" ] ; then
         set -- `ip -o -f $family addr show | grep $7`
         [ "$5" = brd ] && BRDCAST=$6
       fi
     fi
   else
     if [ -z "$OCF_RESKEY_nic" -a "$NETMASK" != "${1#*/}" ] ; then
       ocf_log err "Unable to find nic, or netmask mismatch."
       return $OCF_ERR_GENERIC
     fi
   fi
   echo "$NIC netmask $NETMASK broadcast $BRDCAST"
   return $OCF_SUCCESS
 }