In today’s lab you will enable NAT and watch as packets traverse your router.


You must first follow the instructions inIPTables Howto. Be sure you have NAT enabled and you can ping from your switch VM to google using IPv4.

Capture on Two Interfaces

Capture packets using tcpdump on the internal and external interfaces:

router$ sudo tcpdump -i ens160 -w ens160-capture.pcap icmp &
router$ sudo tcpdump -i ens192 -w ens192-capture.pcap icmp &

Ping From Your Switch

With both captures running execute the following command on your switch:

switch$ ping

Your captures should record the pings as they pass through your router.

Analyze your Pings

After you have a few pings bring both files onto your machine and examine them in Wireshark. You should be able to answer the following question by looking at your packets:

  • What’s the IP address of your switch as seen on ens160?

  • What’s the IP address of your switch as seen on ens192?

Turn In

Submit both of your packet captures on Canvas.