recv(), recvfrom()
http://lxr.free-electrons.com/source/net/socket.c
http://www-numi.fnal.gov/offline_software/srt_public_context/WebDocs/Errors/unix_system_errors.html
http://lxr.free-electrons.com/ident?v=2.6.33;i=ECONNRESET
http://www.binarytides.com/linux-ss-command/
RFC 793 - Transmission Control Protocol
http://www.faqs.org/rfcs/rfc793.html
https://blogs.technet.microsoft.com/networking/2010/08/11/how-tcp-time-wait-assassination-works/
http://*.com/questions/2004531/what-is-the-difference-between-socket-and-serversocket
http://docs.oracle.com/javase/7/docs/technotes/guides/net/http-keepalive.html
http://serverfault.com/questions/421310/check-the-number-of-active-connections-on-port-80
http://www.tcpipguide.com/free/t_TCPConnectionPreparationTransmissionControlBlocksT.htm
http://*.com/questions/152457/what-is-the-difference-between-a-port-and-a-socket
https://tools.ietf.org/html/rfc2068#section-8
https://tools.ietf.org/html/rfc7230#section-6.3
https://tools.ietf.org/html/rfc7540#section-5
http://www.tutorialspoint.com/unix_system_calls/accept.htm
http://*.com/questions/152457/what-is-the-difference-between-a-port-and-a-socket
https://en.wikipedia.org/wiki/HTTP_persistent_connection
http://*.com/questions/410616/increasing-the-maximum-number-of-tcp-ip-connections-in-linux
TCP连接复用(TCP Connection Reuse)
http://blog.csdn.net/chdhust/article/details/12171263
使用netlink的NETLINK_INET_DIAG协议获取所有套接字信息出错
http://bbs.chinaunix.net/thread-3766684-1-1.html
http://lxr.linux.no/linux+v3.2.8/Documentation/networking/ip-sysctl.txt#L464
http://www.linuxquestions.org/questions/linux-networking-3/tcp-ip-stack-source-code-322146/