The repository contains the three projects and the corresponding extra credits I have done in the networking class. The project descriptions(pdf files) are included in each project directory.The README files in each project directory describes the challenges I've faced in implementing the assignments and the two extra credit options I've implemented for each project. 

The first project is building a simplified reliable transport protocol, bears-tp. The second project is implementing a RIP router which simulates distance-vector routing (one of the extra credit is implementing link-state routing based on Dijkstra's algorithm). The first part of the final project is implementing a firewall on a plug computer which bans client's access to certain port, domain and monitor some connection for the occurrences of certain strings.The second part of the final project is building a firewall which could use a protocol called FTP(File Transfer Protocol) while not conflicting two rules in the project spec.The firewall code and extra credits are in ~/proj3/ext.