Problems 7
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TCP/IP Connections

Purpose: To demonstrate your knowledge of TCP/IP and the Unix environment.

Goal: Explain what is necessary to make a network command such as "telnet somehost" work between two Unix machines.

How does the connection get made from your machine to the distant machine over the network?

What Unix files and services are consulted during the connection process?

What Unix commands are useful to debug and observe the connection?

Pick a host on the local network.  Cut-and-paste the output of the Unix commands you would use to debug and observe a connection to this machine.  Annotate the output with explanations of what is happening.
Pick a host on a non-local network.  Repeat the process, showing the new output (cut-and-paste) and explaining what is different about the non-local connection.

Make sure you explain the relevance and utility of the following files and commands:

   /etc/nsswitch.conf
   /etc/resolv.conf
   /etc/hosts
   ping
   traceroute
   ypcat hosts
   netstat -i
   netstat -r
   ifconfig

Explain how the remote Unix machine is able to receive the incoming connection.   What files are involved, and for what are they used?  Include the following files and commands in your explanation:

   /etc/services
   /etc/inetd.conf
   /etc/hosts.allow    (tcpwrappers: Linux only)
   /etc/hosts.deny     (tcpwrappers: Linux only)
   kill -HUP (a process id)

Be clear and concise in your answers.