• Part 1 [30 points total]: Construct a TFTP retrieval client. The client needs to only be able to retrieve a file via TFTP from a given IP address and UDP port and store it into a given filename. The client should only send the Read Request (RRQ) TFTP command and should use the "octet" transfer mode in all cases. The program should time the transfer and calculate the throughput of the data in bits-per-second. In other words, save the start time, st, save the end time, et, and caulate the throughput as file size * 8 / (et - st). This part breaks down into a few pieces.
  • A [10 points]: mechanism to keeping sending a TFTP RRQ to the TFTP server on a given IP address and UDP port until a TFTP Data message is received as an acknowledgement or the RRQ has been sent 10 times. There must be 1 second between RRQ retransmissions.
  • B [10 points]: mechanism to check a TFTP Data message to see if it contains the correct block number expected and to send the corresponding TFTP ACK back to the server. In addition, this mechanism needs to know when a TFTP transfer is complete by looking at the data length.
  • C [10 points]: mechanism to store the transfer start time end time, and maintain a count of total bytes received. In addition, mechanisms to get the filename to store the retrieved data, open the file, and store the retrieved data in the file. The IP address, UDP port, and file to retrieve must be given by a TFTP URL, e.g. tftp://host:port/filename.
• Part 2 [35 points total]: Construct a TFTP server. The server needs to only honor RRQ TFTP commands. The server must be concurrent and only support the "octet" transfer mode. This part breaks down into the following pieces.
  • A [20 points]: mechanism to check a TFTP message to see if it is a correct RRQ (octet mode, file that it can access, etc.). If not, it must send a TFTP Error message back to the client. This mechanism must create a second UDP socket to perform the actual transfer with to allow the main socket to be free to handle other connections. The mechanism here will need to open the requested file and send a TFTP Data message to the client on this new socket.
  • B [15 points]: mechanism to manage the data transfer. It must send a TFTP Data message, wait for an ACK for 1 second, then send the TFTP Data message again if not received. If the same data message is sent 10 times, the transfer should be aborted.
• Part 3 [35 points total]: Construct a packet trace processing tool. You've been asked to build a tool to process packets captured by an Intelligence Agency on the war against terrorism. They want a tool that can read captured packets saved to a file and process them for usage by other signal intelligence (SIGINT) tools. The captured packets are stored as a sequence of records in a file with the format below.

  
   0                             15                              31
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                        Capture Second                         |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                     Capture Microsecond                       |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                          IP Header                           ...
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                       TCP/UDP Header                         ...
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                       Data (Optional)                        ...
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ...                                                             |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                 Capture Second (Packet 2)                     |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |              Capture Microsecond (Packet 2)                   |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                      IP Header (Packet 2)                    ...
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  ...
  

  The capture seconds are measured since the epoch on January 1, 1970. Microseconds is the number of microseconds within that second. This is the standard C timeval structure timing. The processing takes the form of the following.
  • A [10 points]: TCP stream information. IP address and TCP port of each end of the stream, time of each TCP session start and end, and total bytes transfered in each direction.
  • B [10 points]: UDP information. Total bytes from each unique IP address and port combination. Must include the IP address and UDP port of both sender and receiver.
  • C [15 points]: Total statistics. These include: time of start of capture, time of end of capture, total bytes captured, total TCP segments captured, total UDP packets captured, total unique IP addresses to send data, total unique IP addresses as destinations, total unique TCP destination ports, total unique UDP destination ports.

Notes: Your submissions must at least compile before any credit will be given. Submissions that do not compile will not be graded. Submissions submitted after the due date will not be graded. All work must be your own original work. To get partial credit for parts of the assignment, you must demonstrate that those pieces work by themselves. If you share code with others, you will be given a 0 for the assignment. This assignment set is worth 25% of your total grade.

TFTP RFC 1350 at ftp://ftp.ietf.org/rfc/rfc1350.txt

Extra Credit

For extra credit, do one or both of the following:

• Make Part 3 pull out the TCP stream data and save it to a file for each stream [5%]. The name of the file should be srcIP.srcPort-destIP.destPort. The format of the file should be the same as the previous file, but the only thing in the each file should be data for that TCP stream.
• Make Part 3 do more processing for SMTP TCP streams (TCP port 25) [8%]. For those TCP streams, write out a file containing the mail message. You will have to keep track of SMTP commands and responses and strip out only those pieces that are of the email message. In addition, you will need to account for TCP retransmissions of data, etc.

Submission Guidelines