网络栈：
https://blog.csdn.net/zxorange321/article/details/75676063
https://blog.csdn.net/yming0221/column/info/linux-kernel-net
netfilter的架构
https://blog.csdn.net/fangxin205/article/details/54972153
https://blog.csdn.net/wuruixn/article/details/7957368
contrack的讲解：
https://blog.csdn.net/jasonchen_gbd/article/details/44874321
https://www.cnblogs.com/liushaodong/archive/2013/02/26/2933593.html
路由的源码分析：
https://blog.csdn.net/zhuyong006/article/details/79198124
TCP连接的11种状态
https://www.cnblogs.com/qingergege/p/6603488.html
ping包的流程
https://blog.csdn.net/f2006116/article/details/51159895/
SNAT和DNAT：
http://www.cnblogs.com/whych/p/9147900.html
网路接口的/proc/net/dev
https://blog.csdn.net/rheostat/article/details/8363358
内核的链表结构：
https://blog.csdn.net/zhaoxiaoqiang10_/article/details/57081022
