Reference no: EM131109201

Part A

1. Run ifconfig. For all configured interfaces except loopback, there should be an "stet" address, a "HWaddr" (hardware) address, and perhaps even an "inet6" address. Each of these addresses identifies the computer within a certain context. In what context are each of these addresses used? Specifically, for what protocol is the address used, and what other computers can access this one using this address? (Ignore NAT issues.)
2. What does MTU refer to in the output of ifconf ig? Specifically, what does the acronym mean, and what does this value determine?
3. How could you use netcat (nc) to listen on port 9200 and write received data to the file /tmp/foo?
4. What does tracepath slashdot .org return?
5. How can you get netstat to return a list of all current TCP connections and open ports, listed using numeric IP addresses (rather than DNS hostnames)?
6. How could I use lsof to find all of the processes accessing the directory /home?
7. In /proci<PID>/maps, each entry has four permission bits: & p. What do each of them indicate?

Part B
1.  Why does tt acepath return "no reply" sometimes?
2. ] nc uses very few system calls (three on Ubuntu 11.10) when actually receiving data on the network. (The other system calls are tbr setup and tor ending the connection.) What are those few system calls, and what do each of them do?
3. What file does netstat access to find out about current TCP connections on Linux? And, what is the difference between this file and the output of netstat, in syntax and semantics? Be specific.
4.  What does 1 sof sometimes get a "permission denied" error when run as a regular user? Specifically, what files is it hying to access, and why arc these protected?