diff --git a/EduNetworkBuilder/NetworkCard.cs b/EduNetworkBuilder/NetworkCard.cs
index 956cdbf..616ed8b 100644
--- a/EduNetworkBuilder/NetworkCard.cs
+++ b/EduNetworkBuilder/NetworkCard.cs
@@ -513,6 +513,8 @@ namespace EduNetworkBuilder
                     break;
                 case NicType.port:
                 case NicType.wport:
+                    if (tPacket.InboundNic == this) 
+                        break; //This is the port we came in on.  Do not sent it back out this port
                     nPacket = new Packet(tPacket);
                     if (HasBroadcastAddresses(tPacket.destIP))
                     {
@@ -563,6 +565,8 @@ namespace EduNetworkBuilder
             Network mynet;
             NetworkDevice nd;
             //We make sure the MAC matches.
+            if (tPacket == null) return;
+            tPacket.InboundNic = this; //track which nic we came in on.
             if (myNicType == NicType.port || myNicType == NicType.wport)
             {
                 //Try tracking the arp if we can
diff --git a/EduNetworkBuilder/Packet.cs b/EduNetworkBuilder/Packet.cs
index bf091b1..ecc3393 100644
--- a/EduNetworkBuilder/Packet.cs
+++ b/EduNetworkBuilder/Packet.cs
@@ -55,6 +55,7 @@ namespace EduNetworkBuilder
         public bool packet_good = true;
         DateTime StartTime = DateTime.Now;
         public NetworkCard OutboundNic = null;
+        public NetworkCard InboundNic = null;
         public NetworkInterface OutboundIF = null;
         public IPAddress OutboundIP = new IPAddress(NB.ZeroIPString);
         public string OutboundMAC = "";
@@ -323,6 +324,7 @@ namespace EduNetworkBuilder
         public void StartOnLink(NetworkLink theLink, NetworkDevice start_device)
         {
             if (theLink == null) return;
+            InboundNic = null;
             WhereAmI = theLink;
             MyStatus = PacketStatus.moving;
             myLinkPercent = 0;