2.5 Proxy rationale
Use a proxy is to prevent the frequent requests for the same service ip is Fengdiao can no longer initiate a valid request.
Initiating a request using a proxy server, the proxy server is replaced by the present system sends a request to the target site, and then forwards the response data to the machine. That site can see ip is actually a non-native proxy ip ip
2.5.1 proxy role
Break their own IP access restrictions, access to some sites not normally accessible
Some units or groups to access internal resources surprise: for example, using the education network addresses free proxy server, it can be used for all kinds of open education network FTP download upload, and share all kinds of information inquiries and other services
Improve access speed: Proxy servers are usually set up a large hard disk buffer zone, when there are passed outside information, but also to · save it to buffer, when other users access the same information directly from the buffer remove the region information transmitted to the user, in order to improve the access speed
Internet users can also hide the true IP can hide from attack by such a method for crawlers, we use
Acting is to hide the real request IP, IP is blocked to prevent the machine
2.5.2 Classifieds
1 according to a protocol to distinguish
The protocol agent, the agent can be divided into the following categories
FTP proxy server: mainly used to access the FTP server, there are uploading and downloading, and save function, the port is usually 21212
HTTP proxy server is mainly used to access the Web pages, the content filtering and caching function as a port to 80, 8080, 3128
SSL LS Agent: mainly used for access to encrypted website, SSL TLS encryption function (up to 128-bit encryption strength), the port is usually 443
RTSP proxy: mainly used to access the Real streaming media server, there is a cache function, the port is 554
Telnet proxy: mainly used for telnet remote control (computer hacker invasion is often used to hide the identity), like port 23
POP3 / SMTP proxy: mainly used to send and receive e-mail POP3 SMT, there are cache function, port 11025
SOCKS proxy: simply pass packets do not care about the specific protocol and usage, so the save function is very fast, usually port 1080 SOCKS
Agency agreement is divided into SOCKS4 SOCKS5, the former only supports TCP, while the latter supports TC UDP, also supports a variety of authentication mechanisms, DNS server In simple terms, SOCKS4 SOCKS5 can do can be done, but do SOCKS5 to be able to do SOCKS4
2 classified according to the degree of anonymous proxy
Highly anonymous proxy:
The packet will be forwarded intact, it seems as if the server is really a common client access, and record IP is the IP of the proxy server
Ordinary anonymous proxy:
Will do on the data packets may find that this is a proxy server on a number of changes, there are certainly a few
Rate traced to a client's real proxy server typically added Http head has HTTP VIA HTTP X FOR DED FOR
Transparent Proxy:
Not only changes the packet will also tell the server that the client's real IP proxy cache technology can be used in addition to
Surgery to improve browsing speed, content filtering can improve security outside, no other significant effects, the most common example is a hardware firewall within the network
Spy agency:
Generation used to refer to organizations or individuals to create user data record transfer, and research monitoring purposes
Proxy server