Parenthesized numbers after certain keywords refer to corresponding manual page sections, where you will find further information about the keyword. For example man(1) refers to section 1 of the manual pages, and you will find further information about the keyword with command "man 1 man".

1. Networking basics

1.1	Using ifconfig(8), find all the active interfaces on your machine.	1 p
1.2	Using netstat(8) and arp(8), find the mac address of the default router of your machine.	1 p
1.3	From resolv.conf(5), find the default name servers and the internet domain of your machine.	1 p
1.4	Using dig(1), find the responsible name servers for the cse.hut.fi domain.	1 p
1.5	Using dig(1), find the responsible mail exchange servers for cse.hut.fi domain.	1 p

2. Examining the request and response messages of clients and servers speaking a simple, text-based protocol, using HTTP and part of SSH protocols as an example.

2.1	Using netcat, nc(1), capture the version number of the ssh daemon running on your machine.	1 p
2.2	Using netcat, nc(1), craft a valid http/1.1 request for getting http headers (not the html file itself!) for the main index page of www.tkk.fi. What request method did you use? Which headers did you need to send to the server? What was the status code for the request? Which headers did the server return? Explain the purpose of each header.	2 p
2.3	Using netcat, nc(1), start a bogus web server listening on the loopback interface port 8080. Verify with netstat(8), that the server really is listening where it should be. Direct your browser to the bogus server and capture the User-Agent: header.	2 p
2.4	With similar setup to 2.3, startup a bogus ssh server and try to connect to it with ssh(1). Copy-paste the server version string you captured in 2.1 and see if you get a response from the client. What is the client trying to negotiate?	2 p

3. Examining the connection setup more closely.

3.1

Using xinetd(8), startup a telnetd(8) server, if it's not already running. Also start capturing traffic on the loopback interface with tshark(1). Connect to the server with a telnet(1) client. What kind of option negotiation (in Telnet Data packets) are the server and the client going through? Find the rfc describing the options, and explain in your own words, what do they agree upon echoing characters (pay attention to port numbers for direction of the messages).

4 p

4. Improving this assignment (Optional)

4.1

How would you improve this assignment? You can suggest something to be done or asked in the exercise, or something to be left out. Please report any errors and typos, and also let us know if you did not understand some question. Was the assignment too easy or too hard? Estimate also how much time did you spend on this assignment.

2 p