This is the homework of Advanced Programming for Internet in Harbin Institute of Technology.

The repository contains two projects:

A TCP and UDP multiplex service for file transfer service using select.

The server can accept both TCP and UDP connections.

Packet sniffers that intercept the network traffic flowing in and out of a system through network interfaces.

The sniffer uses a raw socket when put in recvfrom loop receives all incoming packets Learn More.

Note: You need to compile this project in Linux or Unix (including Mac OS X).

You can simply compile this project use make command.

After the compile operation is successful, you can run the server:

./server <PortNumber>

Then you can start a UDP client or TCP client:

# for TCP client
./tcp-client <ServerIP> <PortNumber>

# for UCP client
./udp-client <ServerIP> <PortNumber>

In TCP client, you can get files from the server:

GET <Path to the file in server>

Known issues:

• Segment fault will be raised if the path is invalid or the file doesn't exist in server.
• Segment fault will be caused if you have no previlige to save the file in client.
• The client may be blocked for unknown reason while transfering files.

Note: In Linux/Unix systems, you need root permissions to receive raw packets on an interface. This restriction is a security precaution, because a process that receives raw packets gains access to communications of all other processes and users using that interface.

sudo ./packet-sniffer

All incoming packets will dumped into packet-sniffer.log file.

This project is open sourced under Apache license.