http://proneer.tistory.com/entry/TCP-FlagSYN-ACK-FIN-RST-PSH-URG

http://cities.lk.net/tcp.html

http://blog.naver.com/PostView.nhn?blogId=sunlit79&logNo=140162726860&parentCategoryNo=25&categoryNo=&viewDate=&isShowPopularPosts=false&from=postView