centos6.5 installation tutorial

Squid role

##1Forward proxy

Standard proxy buffer server,The IP address and port number of the proxy server must be clearly specified on the browser of each internal host.

Transparent proxy buffer server,The proxy operation is transparent to the client's browser (that is, there is no need to specify the proxy server IP and port)Iptables or Ipchainsimplementation

Reference

2.Squid optimizes the architecture, caches websites, and improves web application access performance

Principle

When Squid first receives a request for a special resource, Squid often starts from the original server Confirm it. If the server indicates that Squid's copy is still valid, the data is sent. Otherwise, Squid updates its cached copy and forwards it to the client. Squid will clear the cache to free up space for new objects.

Workflow

When the proxy server has the data required by the client:

a. The client sends a data request to the proxy server;

b. The proxy server checks its own data cache ;

c. The proxy server finds the data the user wants in the cache and takes out the data;

d. The proxy server will retrieve the data from the cache The data obtained is returned to the client.

When the proxy server does not have the data required by the client:

1. The client sends a data request to the proxy server;

2. The proxy server checks its own data cache;

3. The proxy server does not find the data the user wants in the cache;

4. The proxy server sends a data request to the remote server on the Internet;

5. The remote server responds and returns the corresponding data;

6. The proxy server obtains the data from the remote server, returns it to the client, and keeps a copy in its own data cache

　

Detailed reference:

2. Hardware impact on performance

Memory and disk space have an impact on performance, memory shortage Will seriously affect performance. More disk space means more cache targets and higher hit rates. SCSI disks perform better than ATA. The basic rule is that each G of disk space requires 32M of memory. In this way, a system with 512M memory can support 16G disk cache

The typical cache hit rate of Web cache is between 30% and 60%

squid installation

Operating system: centos6.5

squid version: squid-3.1.23-24 .el6.x86_64.rpm

3.1 Check whether it is currently installed

rpm -qa squid

3.2 yum installation

yum -y install squid

4. Configuration

4.1 Directory structure after installation

Main program:

##/usr/sbin/squid

Script:

/etc/init.d/squid

Configuration file

/etc/squid/squid.conf

Default access log file:

/var/log/squid/access.log

4.2squid.conf file configuration

vi /etc/squid/squid.conf make the following configuration

http_port 192.168.252.11:3164 #Listening port (for security reasons, add the IP address in front, Squid will not listen to the external network interface)

cache_dir ufs /var/spool/squid 100 16 256 //Define Squid's cache storage path. The cache directory capacity is 100M. There are 16 first-level cache directories and 256 second-level cache directories.

--Must be at the end of the configuration file Add the following statement below, otherwise Squid cannot start!

visible_hostname localhost

--Configure some ip addresses to be accessible

acl normal src 192.168.101.1-192.168.101.250/32

http_access allow normal

#cache access_log /var/log/squid/access.log Set the access log file

#cache store_log /var/log/squid/store.log Set the web cache Log file

#cache effective user/group squid

5. Start

--Create cache directory

cd /usr/sbin/squid

./squid -z

2017/06/30 15:13:54| Creating Swap Directories

2017/06/30 15:13:54| /var/spool/squid exists

2017/06/30 15:13:54| Making directories in /var/spool/squid/00

2017/06/30 15:13:54| Making directories in /var/spool/squid/01

2017/06/30 15:13:54| Making directories in /var/ spool/squid/02

2017/06/30 15:13:54| Making directories in /var/spool/squid/03

2017/06/30 15:13:54| Making directories in /var/spool/squid/04

2017/06/30 15:13:54| Making directories in /var/spool/squid/05

2017/06/30 15:13:54| Making directories in /var/spool/squid/06

2017/06/30 15:13:54| Making directories in /var/spool/squid/07

2017/06/30 15:13:54| Making directories in /var/spool/squid/08

2017/06/30 15:13:54| Making directories in /var/spool/squid/ 09

2017/06/30 15:13:54| Making directories in /var/spool/squid/0A

2017/06/30 15:13:54| Making directories in /var/spool/squid/0B

2017/06/30 15:13:54| Making directories in /var/spool/ squid/0C

2017/06/30 15:13:54| Making directories in /var/spool/squid/0D

2017/06/30 15:13:54| in /var/spool/squid/0E

2017/06/30 15:13:54| Making directories in /var/spool/squid/0F

iptables Corresponding configuration

If it is a normal proxy, you need to configure the NAT table of iptables, and forward access to port 80 to the squid port

iptables -t nat -A PREROUTING -s specify the ip segment- p tcp --dport 80 -j REDIRECT --to-port 3164

If it is a non-transparent proxy, you need to develop the Squid port

iptables -A INPUT - s specifies the ip segment -p tcp --dport 3164 -j ACCEPT

iptables -A OUTPUT -p tcp --dport 3164 -j ACCEP

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