Test #1 will be in class on Friday, March 5th (for local students). The test will be closed book/notes, no calculators are allowed (or needed). See Dave if you have a problem with the schedule (I realize that Friday before spring break may not be possible for everyone...).

Remote Students: You can take the test any time before March 13th (whatever day is OK with your site coordinator/proctor is fine with us).

Topics and Readings What to expect Networking and the OSI Reference Model (lecture notes) Lan/Wan Multiaccess vs. Point-to-point networks OSI Reference Model Physical Layer Datalink Layer Network Layer Transport Layer Network Components Repeater Bridge Router Gateway Modes of Service Connection-Oriented vs. Connectionless Service Sequencing Error Control Flow Control Stream vs. Message Oriented service End-to-end vs. Hop-by-hop Broadcasting know what the datalink, network and transport layers are responsible for. Know what a bridge/router/gateway is. Understand the difference between connection-oriented and connectionless services (network and transport services). Know what a broadcast is. TCP/IP (lecture notes, Chapter 2) IP IP Addresses ARP/RARP ICMP UDP TCP 3-way handshake Termination TCP Segments Know where IP, TCP and UDP are in the OSI reference model. Know what an IP address is. Know about the TCP 3-way handshake that initiates a connection. Know about termination of a TCP connection (FINs). The role of ARP (what it does, why it is necessary). Sockets Programming (lecture notes, Chapter 3.1-3.6, 3.9, Chapter 4, 8.1-8.11,8.14) Generic Network API socket() struct sockaddr_in Network Byte Order bind() TCP Programming listen() accept() connect() using read() and write() with TCP sockets UDP Programming sendto() recvfrom() using connect() with UDP sockets Understand the sockets is a generic network API. be familiar with the basic socket functions/system calls. be familiar with a sockaddr and sockaddr_in understand network byte order (when it is used and why). differences between TCP and UDP programming (mechanics) Reading from a TCP stream (what can you expect?). Be able to understand or write a little code that uses sockets. Internet Protocol Case Studies: TELNET protocol (RFC 854) Network Virtual Terminal - layered model. Data and Control over same connection negotiated options HTTP (RFC 1945) requests replies headers Domain Name System (lecture notes, Chapter 11.1-11.4, RFC 1034) Hostnames Domains DNS Clients & Servers Recursion TFTP (RFC 1350) Simple connectionless protocol Sorcerer's Apprentice Syndrome Basic understanding of all 4 services. Understand HTTP and TFTP protocols TELNET - understand how data and control can be intermixed in the same stream. TFTP - sorcerer's apprentice syndrome. I/O Multiplexing (lecture notes, Chapter 6.1, 6.3) Blocking vs. Nonblocking I/O select() What select() does, when this is useful and how to use select(). Buffer Overflow (lecture notes and sample code) What it means to overflow a buffer, and why this is bad. Why potential buffer overflow is not acceptable in network programs How to avoid the problem. Be able to describe the problem at a high level (you don't need to understand all the details). Be able to identify code that has a potential buffer overflow! Web Programming (lecture notes and examples) Custom Server Server Side Includes CGI Programming Request types (GET, POST) HTML forms how requests get forwarded to CGI programs how response is sent back to client What Server Side Includes means. CGI (what it is). The relationship between an HTML form and a CGI program Programming Sockets Programming in C Be able to write a small sockets program. No need to memorize socket/system call parameters, but you should know the names of the functions! Know how(and when) to use select()! Be able to describe what a C program does (a program that includes some sockets system calls - is it a client? server? tcp? udp?, etc).

Sample Questions:

• What is the OSI Reference Model?

• Describe how you would write a single-process, single-thread server that could be both a UDP echo server and a TCP echo server. Provide pseudo code for this server (show the form of the code including where system calls are made, but don't worry about the details of system call parameters, etc). Your server can be iterative, but you cannot assume that you will get a TCP client,followed by a UDP client, followed by a TCP client,...

• Describe the network traffic that results from the normal termination of a TCP connection.

• What does the listen() system call do?

• Given an HTML form, compose a valid HTTP request that could be sent (assuming the user fills out the form and presses the submit button).

• Describe the difference between the HTTP GET and POST methods.

• What is a Network Virtual Terminal ?

• Why is network byte order important?

• Describe the Domain Name System network service.

• Given a C program for a server, identify any possible buffer overflow situations. Describe the structure of a specific query that could be sent by a bad guy to exploit the buffer overflow.

• Write a TCP client that connects to a server and sends anything read from STDIN to the server and anything received from the server is sent to STDOUT.

• Write a UDP echo server (sends any message received back to the sender).

• Write an echo server that can handle both TCP and UDP clients (hint: multiplexing).

• How many network programmers does it take to screw in a light bulb?