Homework 1

Problems from Kurose and Ross, 6th Edition

A.  Page 68. Questions: R11, R12, R16, R19. Page 70. P3.a P3.b, P6, P7, P8, P13, P14, P24, P16 (this has a typo: ignore the given average queuing delay. Only use the average N and transmission delay), P22, P23.

B. Use trace route to determine the number of hops to 3 destinations of your choice. (Try to include destinations not in the US .) Turn in a listing of the destination IP and the IP of each router between you and the destination. If possible, include the name of the company that owns each router.

D. Find open ports and applications. Download and use CurrPorts to determine which ports are open on your machine. Turn on a screem shoot with the open ports circled (use windows snipping tool, or similar)

E. Find open ports on other machines. Download and use Nmap to determine ports open on your home gateway/NAT. Specifically, while at home, run Nmap to scan your gateway/NAT. In windows, use ipconfig to determine the IP address of your gateway/NAT. In Linux, use ifconfig. Turn in a list of the open ports and likely applications.

D. Do connections experience time-varying delay? Yes, however, you need to look carefully. The delay can change because of two reasons, namely, because the route changes and because the congestion changes. Use ping to find an example of a connection where the delay varies. Specifically, run trace route and ping at different times of the day (e.g., the middle of the night, morning, afternoon, etc., or maybe just run ping for an entire day) and compare the delay times. (Make sure to try destinations not in the US . Also, use IP addresses instead of names. Use nslookup to translate between names an IP addresses.) One way to do this is use "ping XXXX.com -t > PingData.txt." Then open the file in a text editor to remove the first few lines and last few lines and remove the letters "ms" (use the replace function for this). So, when you are done, the file has many lines like this:

...

Reply from 66.218.71.198: bytes=32 time=79 TTL=243

Reply from 66.218.71.198: bytes=32 time=80 TTL=243

...

Then open this file in Matlab (or excel) and make a plot of RTT. Also, plot the TTL.