Network

1. Overview 最初的TCP因为不支持拥塞控制而频繁被丢弃数据包，协议栈被投入使用8年后，Van Jacobson在1988年将 TCP 拥塞控制引入网络。 IP层并没有提供拥塞控制功能，各个主机不知道什么是合理的速度。理想场景利用负反馈控制窗口，每一个TCP连接，引入变量CongestionWindow与SlowStartThreshold。 ...

1. Definition of security confidentiality: only sender, intended receiver should “understand” message contents sender encrypts message receiver decrypts message authentication: sender, receiver want to confirm identity of each other message integrity: sender, receiver want to ensure message not altered (in transit, or afterwards) without detection access and availability: services must be accessible and available to users. Access is the basis of availability. Without network security, the intruder can eavesdrop, insert messages, impersonation, hijacking(taking over ongoing connection), denial of service and so on. ...