E11 Measuring TCP and UDP

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Back to the Material: TCP, UDP and Controlling our Network Configuration (SSH, HTTP)

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Video: Instructions for E11

Topology

This exercise follows E10, thus uses its working configuration.

Preparing the topology

If everything was fine earlier, there is nothing to do/change.

iperf

Test from home to Internet

1. Change your Lubuntu VM to bridged network and ensure it gets an IP address from your home network
2. Perform iperf -c iperf.he.net on the Lubuntu VM
   • if iperf.he.net is not available... find a suitable public iperf server to replace it
3. Try other settings for iperf towards that server (e.g. -u, etc)
4. Investigate, ponder upon and document the results

Test within your exercise network

Verify connectivity between two Lubuntu's in your exercise network. Choose one to be the iperf server and the other to be iperf client

1. Setup a server
   • Open the Qterminal and use the iperf -s commands
2. Use the client to connect to the server's IP address with iperf -c
3. Try other settings for iperf towards that server (e.g. -u, etc)
4. Investigate, ponder upon and document the results

Investigating TCP/UDP connections

1. Prepare a third Lubuntu (in addition to the server and client Lubuntu) for wiresharking the environment
2. Set its adapter to the link forwarding the traffic between your hosts and start to record it!

Wireshark a three-way-handshake between your Lubuntu's

1. Open Firefox from the client Lubuntu
2. Browse to the http://[server ubuntu IPv4 address] (e.g. http://172.16.0.10)
3. Investigate the wireshark capture for the three-way-handshake
4. Take a picture of each of the three-way handshake packets
5. Document the pictures with short explainations of what is happening in each of the TCP headers

Wireshark a DHCP process between your Lubuntu & Vyos

1. Shutdown the first Lubuntu virtual machine
2. Start to wireshark (with the third lubuntu machine) the ethernet segment in front of the first Lubuntu machine
3. Start it with wiresharking on in the same ethernet segment
4. Investigate the wireshark capture for the UDP communications between the DHCP server (vyos) and the DHCP client (Lubuntu)
5. Document the pictures of the UDP transmission with short explainations of what is happening in each of the TCP headers

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License

This course and its materials are written by Karo Saharinen and licenced by Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) license.