这篇博文详细说明解释了TCP/UDP！帮助很大！
TXP/UDP详解
https://blog.csdn.net/hansionz/article/details/86435127?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522164448177816780357266653%2522%252C%2522scm%2522%253A%252220140713.130102334..%2522%257D&request_id=164448177816780357266653&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~sobaiduend~default-1-86435127.first_rank_v2_pc_rank_v29&utm_term=TCP%2FUDP&spm=1018.2226.3001.4187
