There are many proxy software, squid is the popular one, but I don’t want to install it as I can reuse the Apache’s proxy function. Below I will introduce how to setup the forward proxy with authentication function in Apache 2.2.x.(The example based on Apache 2.2.x shipped with Oracle Linux 6)

• Edit /etc/httpd/conf/httpd.conf, make sure mod_proxy module has been set to be loaded

LoadModule proxy_module modules/mod_proxy.so

• Make sure the /etc/httpd/modules/mod_proxy.so exists

• Find the mod_proxy keyword, and add following

<IfModule mod_proxy.c>
    ProxyRequests On
    ProxyRemote * http://<upper proxy IP>:<port>
	
   <Proxy *>
      Order deny,allow
      Deny from all
      Allow from all
      AuthType Digest
      AuthName <Realm Name>          <--- Realm Name
      AuthDigestDomain /             <--- Digest prtected domain
      AuthUserFile <digest password file>   <--- Password file generated by htdigest command
    require user <username>
   </Proxy>

• Generate a digest password file contains the user/password info

#htdigest -c <filename> <Realm Name/AuthName> <Username>
>> <--- input password the first time
>> <--- input password the second time