1 files changed, 17 insertions, 5 deletions

diff --git a/scripts/runqemu-ifup b/scripts/runqemu-ifup
index 987a37a1a7..870cb6bcb7 100755
--- a/scripts/runqemu-ifup
+++ b/scripts/runqemu-ifup
@@ -69,12 +69,29 @@ if [ "x$IFCONFIG" = "x" ]; then
         # better than nothing...
         IFCONFIG=/sbin/ifconfig
 fi
+if [ ! -x "$IFCONFIG" ]; then
+        echo "$IFCONFIG cannot be executed"
+        exit 1
+fi
 
 ROUTE=`which route`
 if [ "x$ROUTE" = "x" ]; then
         # better than nothing...
         ROUTE=/sbin/route
 fi
+if [ ! -x "$ROUTE" ]; then
+        echo "$ROUTE cannot be executed"
+        exit 1
+fi
+
+IPTABLES=`which iptables 2> /dev/null`
+if [ "x$IPTABLES" = "x" ]; then
+        IPTABLES=/sbin/iptables
+fi
+if [ ! -x "$IPTABLES" ]; then
+        echo "$IPTABLES cannot be executed"
+        exit 1
+fi
 
 n=$[ (`echo $TAP | sed 's/tap//'` * 2) + 1 ]
 $IFCONFIG $TAP 192.168.7.$n
@@ -83,11 +100,6 @@ dest=$[ (`echo $TAP | sed 's/tap//'` * 2) + 2 ]
 $ROUTE add -host 192.168.7.$dest $TAP
 
 # setup NAT for tap0 interface to have internet access in QEMU
-IPTABLES=`which iptables`
-if [ "x$IPTABLES" = "x" ]; then
-        IPTABLES=/sbin/iptables
-fi
-
 $IPTABLES -A POSTROUTING -t nat -j MASQUERADE -s 192.168.7.0/24
 echo 1 > /proc/sys/net/ipv4/ip_forward
 $IPTABLES -P FORWARD ACCEPT