if_port_forward lets a slice forward traffic from one port to another

for its allocated IP addresses. Hack for DONAR on mlab for now, but
likely to come in useful later.

diff --git a/exec/if_port_forward b/exec/if_port_forward
new file mode 100755 (executable)
index 0000000..36451c9
--- /dev/null
+++ b/exec/if_port_forward
@@ -0,0 +1,18 @@
+#!/usr/bin/perl
+
+$|=1;
+$slice=$ARGV[0];
+$slice_ip=`cat /etc/vservers/$slice/interfaces/0/ip`;
+$src_port = <STDIN>;
+$dst_port = <STDIN>;
+
+chomp($slice_ip);
+chomp($src_port);
+chomp($dst_port);
+
+die ("Src and dst ports need to be numbers") if (($src_port=~/[^0-9]/) || ($src_port=~/[^0-9]/));
+
+$IPTABLES_CMD="/sbin/iptables -t nat -A PREROUTING -m tcp -p tcp -d $slice_ip --dport $src_port -j DNAT --to-destination $slice_ip:$dst_port";
+print "Invoking port forwarding command: $IPTABLES_CMD\n";
+system($IPTABLES_CMD);
+print "Done.\n";