Excellent proxy server Software under Linux system: Squid

As a free network operating system, Linux is more and more popular with the network enthusiasts, the current Internet run a large number of hosts are Linux, and China has to Linux as a government Internet designated network operating system. There are signs that Linux is gradually maturing.

In order to solve the contradiction between the rapid development of Internet and the resource tension of IP address, proxy server is used more and more widely. Squid is a very good proxy server software that is used in Linux systems.

Agent Service

A proxy service is a machine with a standard IP address that replaces a number of machines without a standard IP address and other hosts on the internet, which is called a proxy server. When a machine with an internal address wants to connect to the Internet, the request is first sent to a proxy server with a standard IP address, which is sent by the proxy server to the requested destination address through its standard IP address. Then the destination address server sends back the result to the proxy server, and the proxy server will send the data to the internal host again intact. Several machines with internal addresses make up the intranet, and the proxy server is to communicate the intranet and the Internet to solve the problem of intranet access to the Internet. This agent is irreversible, the host on the Internet can not access any one with internal address of the machine, so as to ensure the security of internal data.

One advantage of the agent software is that it can test many things other than the packet. Squid tests the payload of the packet, which is the portion of the TCP (or UDP) part of the packet traversing the firewall. Depending on the packet header (the IP portion of the packet) and the packet Payload (TCP portion), the proxy firewall is able to determine where the packet will be sent, what the packet requests, and what action to take based on the information that the packet must provide.

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.

Compile Install Squid

There are two kinds of squid packages: one is the RPM package used by Redhat and the other is the source code package.

Installation of RPM Package:

1. Enter/mnt/cdrom/redhat/rpms.

2. Implementation of RPM-IVH squid-2.2.stable4-8.i386.rpm.