--- dhclient-script.orig	2006-12-22 19:54:56.000000000 +0100
+++ dhclient-script.orig	2006-12-22 20:13:47.000000000 +0100
@@ -135,6 +135,75 @@ 
   exit_with_hooks 0
 fi
   
+# simple IP arithmetic functions:
+
+function quad2num()
+{
+    if [ $# -eq 4 ]; then
+       let n="$1<<24|$2<<16|$3<<8|$4"
+       echo $n;
+       return 0;
+    fi
+    echo '0';
+    return 1;
+}
+
+function ip2num()
+{
+    IFS='.' quad2num $1;
+}
+
+function num2ip()
+{
+    let n="$1";
+    let o1='(n>>24)&0xff';
+    let o2='(n>>16)&0xff';
+    let o3='(n>>8)&0xff';
+    let o4='n & 0xff';
+    echo $o1.$o2.$o3.$o4;
+}
+
+function mask()
+{   
+    ip=$1
+    m=$2
+    let ip=`IFS='.' ip2num $ip`;
+    let m=`IFS='.' ip2num $m`;
+    let n='ip&m';
+    num2ip $n;
+}
+
+function routerReachable()
+{ # Handle silly DHCP servers that give us a router not on our subnet:    
+    router=$1
+    routerSubnet=`mask $router $new_subnet_mask`
+    mySubnet=`mask $new_ip_address $new_subnet_mask`
+    unreachable=0
+    if [ "$routerSubnet" != "$mySubnet" ]; then
+	unreachable=1
+	if /sbin/arping -f -q -I $interface -w2 $router; then
+	    /sbin/route add ${router}/32 dev $interface
+	    if [ $? -eq 0 ]; then
+		unreachable=0
+	    fi
+	else
+	    unreachable=1
+	fi;
+    fi;
+    return $unreachable;
+}
+
+function add_default_gateway()
+{
+    router=$1
+    metric=$2
+    if routerReachable $router ; then
+	/sbin/route add default gw $router $metric dev $interface;
+	return $?;
+    fi;
+    return 1;
+}
+
 if [ x$reason = xBOUND ] || [ x$reason = xRENEW ] || \
    [ x$reason = xREBIND ] || [ x$reason = xREBOOT ]; then
   current_hostname=`hostname`
@@ -172,7 +241,7 @@ 
       	dev $interface
     fi
     for router in $new_routers; do
-      route add default gw $router $metric_arg dev $interface
+      add_default_gateway $router $metric_arg
     done
   fi
   if [ x$new_ip_address != x$alias_ip_address ] && [ x$alias_ip_address != x ];