Today’s topic is about some debugging methods and toolkit used to solve problems. One is the tcpdump and other terminal tools for remote package sniffer and traffic analysis. Another is some wired errors occurred in the development progress of project.

Nowadays, the OAuth 2.0 is the most popular stander for authorization and also widely used in the third-party authentication process. Beside, there are lots of other protocols uesd for that purpose. Here in this post, the focus is on the CAS -- Central Authentication Service. (Wiki:CAS) as well as the same named implementation.