From: Sapan Bhatia <sapanb@cs.princeton.edu>
Date: Fri, 30 Apr 2010 18:58:50 +0000 (+0000)
Subject: Make sure only one instance of the port-forwarding rule is inserted.
X-Git-Tag: vsys-scripts-0.95-17~2
X-Git-Url: http://git.onelab.eu/?p=vsys-scripts.git;a=commitdiff_plain;h=c57a1628286a502b45358326d551b94596455fda

Make sure only one instance of the port-forwarding rule is inserted.
---

diff --git a/exec/if_port_forward b/exec/if_port_forward
index 36451c9..400591b 100755
--- a/exec/if_port_forward
+++ b/exec/if_port_forward
@@ -12,7 +12,14 @@ 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);
+$IPTABLES_CMD_1="/sbin/iptables -t nat -D PREROUTING -m tcp -p tcp -d $slice_ip --dport $src_port -j DNAT --to-destination $slice_ip:$dst_port";
+
+$IPTABLES_CMD_2="/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 "Removing any previous instances of this rule: $IPTABLES_CMD_1\n";
+system($IPTABLES_CMD_1);
+
+print "Adding forwarding rule: $IPTABLES_CMD_2\n";
+system($IPTABLES_CMD_2);
+
 print "Done.\n";