Update subnet-up.tmpl

tinc/subnet-up.tmpl

@@ -1,2 +1,12 @@
 #!/bin/ash
 echo "Route up: \$SUBNET weight \$WEIGHT via \$NODE (\$REMOTEADDRESS:\$REMOTEPORT)"
+nonMACChars=`echo \$SUBNET | tr -d "[:digit:]" | tr -d [:ABCDEF]`
+macFile="/tmp/tinc_peer_mac_\$NODE"
+if [ -z "\$nonMACChars" ]; then
+  # This subnet is a MAC
+  echo "\$SUBNET" > \$macFile
+else
+  # This subnet is likely an IP address, add it to the ARP table
+  mac=`cat \$macFile`
+  arp -s "\$SUBNET" "\$mac"
+fi