7. Virtual Router with NAT

Goal: Setup a Virtual Router with one interface performing NAT on outgoing traffic. Return to LANforge-ICE Cookbook

In this test scenario, a pair of Virtual Routers are connected with a Redirected Interface connection with one side of the connection performing NAT on outgoing traffic. Two additional Redirected Interface connections are configured to pass traffic and demonstrate NAT.

1. Setup two Virtual Routers and three Netsmith Connections.

   A: Right-click inside the Netsmith window and select New Router
   B: Repeat to create another virtual router
   C: Right-click inside the Netsmith window and select New Connection
   D: Select the 'Skip' option on Port 1-B, WanLink and Port 2-B, then click OK
   E: Repeat and create two more connections
   F: Click the Apply button followed by the Sync button • NOTE:   Modifications in Netsmith are only sent to the LANforge-Server after Applying them • Clicking Sync makes sure any changes are synchronized with the current database

   • For more information, see the LANforge-GUI User Guide: Virtual Interfaces
   • Return to LANforge-ICE Cookbook
2. Setup the Ports.

   A: Right-click the rdd ports and select Modify Port • Assign each pair of rdd ports a unique subnet and IP address
   B: Select the 'IPv4s' checkbox to view the IP addresses of the rdd ports
   C: Configure rddVR3 and rddVR5 with a Gateway IP that corresponds to their peer rdd interface • NOTE:   In this example, rddVR3 has a Gateway IP of 20.20.20.1 and rddVR5 has a Gateway IP of 30.30.30.1

   • For more information, see the LANforge-GUI User Guide: Ports (Interfaces)
   • Return to LANforge-ICE Cookbook
3. Move the Redirected Interfaces into their desired positions.

   A: Drag rddVR0 into Router R0(1) and rddVR1 into Router R1(2)
   B: Drag rddVR2 into Router R0(1) and rddVR4 into Router R1(2)
   C: Click Netsmith Apply to commit the changes

   • Return to LANforge-ICE Cookbook
4. Create a TCP connection and sniff traffic without NAT.

   A: Go to the Layer-3 tab and click Create
   B: Create a Layer-3 TCP connection between endpoints rddVR3 and rddVR5 then click OK
   C: In Netsmith, right-click the TCP connection and click Start
   D: Right-click port rddVR1 and click Sniff Port • NOTE:   You must have Wireshark properly installed as described here: Installing Wireshark
   E: After Wireshark begins, notice that the source and destination IP addresses are from 20.20.20.20 (rddVR3) and 30.30.30.30 (rddVR5) as expected without NAT enabled

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5. Enable NAT and sniff traffic on the same port.

   A: Right-click on the TCP connection and select Stop
   B: Right-click rddVR0 and select Modify
   C: Select the 'NAT' checkbox and click OK, then click the Netsmith Apply button
   D: Right-click on the TCP connection and select Start
   E: Right-click port rddVR1 and select Sniff Port
   F: After Wireshark begins, notice that any source or destination IP address from or to 20.20.20.20 (rddVR3) has been NAT'd to be 10.10.10.10 because rddVR0 is now performing NAT on all outgoing traffic

   • For more information, see the LANforge-GUI User Guide
   • Return to LANforge-ICE Cookbook

  Email Candela Technologies at: support@candelatech.com if you have any questions or suggestions.