Using Squid routine proxy to realize the Internet sharing in intranet

A simple introduction of squid

Through Squid Proxy server to achieve intranet users to share the Internet, configure Squid cache and basic access control to accelerate and restrict access to Web services.

For web users, squid is a high-performance proxy caching server that speeds up the intranet browsing the Internet and increases the client's access hit rate. Squid not only supports HTTP protocol, but also supports FTP, Gopher, SSL and WAIS protocols. Unlike general proxy caching software, squid handles all client requests with a separate, modular, I/O-driven process.

Squid caches the data elements in memory while also caching the results of DNS lookups, in addition to supporting non modular DNS queries that negatively cache failed requests. Squid supports SSL and supports access control. The maximum bandwidth savings are achieved by using ICP,SQUID to enable overlapping proxy arrays.

Squid consists of a main service program squid, a DNS query program dnsserver, several rewrite requests and perform authentication procedures, and several management tools. When squid is started, it can derive a specified number of dnsserver processes, and each dnsserver process can perform a separate DNS query, which greatly reduces the time the server waits for DNS queries.

Squid's other advantage is that it uses access control lists (ACLs) and access permission lists (ARL). Access control lists and access lists to reduce the potential of illegal Internet connections by blocking specific network connections, you can use these checklists to ensure that hosts on your intranet do not have access to a threatening or inappropriate site.

Squid requirements for the hardware is that the memory must be large, should not be less than 128M, the faster the speed the faster the better, the best use of server-specific SCSI hard disk, the processor requirements are not high, 400MH more than can.

Second, squid agent principle of realization

1, the client to the proxy server squid to make access to the Internet request

2, after the proxy server accepts the request, first, in contrast to access rules in the Access control list, if the rules are met, find out if there is a need for information in the cache, if the information in the cache is needed, it is returned directly to the client, and if it does not exist, the proxy server will send an access request to the Internet instead.

3, the main opportunity on the Internet back to the proxy server request information, at the same time, the proxy server will get the data in their own cache, and then the Internet to respond to the information to the client.

4, other clients to the proxy server squid when the same request to access the Internet, the proxy server first and the access control list of access rules in contrast, if the rules are met, the data in the cache to the client

Simply use a logical diagram to introduce

(1) If there is a client-requested data in the cache, take the 1234 route;

(2) If the cache does not have the requested data, go 125634 routes.