Understanding of the Security Gateway!

Recently wrote some articles about the gateway, said to be written, rather than copy, before the firewall, encryption machine, network gate, VPN security gateway and other related equipment, can say just heard, nothing in-depth understanding. This time, in order to write a cryptographic machine operating norms, and the network gate operating norms, it is a charge of the strength of the breast. Finally, it's finished. And these two articles, also in Baidu and Google search, almost no article in this respect, hehe, narcissism bar.

Their own understanding, these gateway devices, it is quite simple to say, of course, this is also a sermon. The firewall should mainly focus on filtering some illegal information, while the encryption machine emphasizes the data at both ends of the encrypted communication, and the network gate is through the "ferry" to prevent hackers, steal core data. and VPN security gateway, is similar, through several VPN technology, the earliest for PPTP,L2TP, and then developed the GRE,IPSEC,SSL and other VPN technology. The preceding is tunneling on the data link layer of the OSI mode. The latter is at the IP layer or even higher, such as SSL, which is based on the application layer of secret technology.

Oneself is also vague, just read a few articles only, so also not standard!