A proxy server
can be useful regarding security. Proxy servers can also act as a cache
that enables users to get faster internet access. At the same time, this server allows them to share downloads more easily. Squid
is a web proxy server
that is secure and it has good caching facilities too. In computers based on Ubuntu
operating systems, this Proxy server
can be installed. This can be done by entering the required commands in the terminal of Ubuntu
. It is also important to configure the proxy server
after the installation process is completed.
1.Installing the proxy
To install Squid type the following command in a terminal:
sudo aptitude install squid
2.Configuring the proxy
Configuration of Squid is done by editing the following file: /etc/squid/squid.conf
To edit this file, type Alt+F2
and enter the following command:
gksu gedit /etc/squid/squid.conf
2.1.Naming the proxy
Its important that Squid knows the name of the machine. To do this, locate the line visible_hostname
For example, if the machine is called ubuntu
2.2 Choosing the Port
By default, the proxy server will use port 3128. To choose another port, locate the line:
and change the port number, for example:
2.3.Choosing the interface
By default the proxy server will listen on all interfaces. For security reasons, its better to put it on your local network only. For example, if the network card connected to your LAN has IP 10.0.0.1, change the line:
2.4. Setting access rights and priorities
By default, nobody else is allowed to connect to the proxy server. A list of permissions must be created.
For example, we will define a group encompassing the local network.
Find the line beginning with acl localhost...
At the end of the section, add:
acl lanhome src 10.0.0.0/255.255.255.0
(lanhome is a random name chosen).
2.5. Authorizing access to group
Now that the group is defined, we will authorise it to use the proxy.
Locate the line http_access allow ...
and add below (before the line http_access deny all):
http_access allow lanhome
2.6. Allow the use non-standard ports
By default, Squid allows HTTP traffic only on specific ports (e.g. 80). This can cause problems on websites using other ports.
To avoid this deadlock, find the line http_access deny! Safe_ports
and the edit it to: # http_access deny! Safe_ports
3.Starting the Proxy
Restart the proxy to apply the modifications you made. Type:
sudo /etc/init.d/squid restart
The proxy logs are located in: /var/log/squid/access.log
Changing the size of the cache
- The Squid cache is enabled by default, which helps accelerate the loading of some pages.
- The default allocated size is 100 MB (found in /var/spool/squid)
- To change its size, edit the /etc/squid/squid.conf file.
- Find the line: # cache_dir ufs /var/spool/squid 100 16 256
- Edit it. You can change the value 100 to whatever you want (e.g. 200 for 200 MB): cache_dir ufs /var/spool/squid 200 16 256
Functions and additional modules
Squid is full of options and modules:
- Prefetch (to preload the pages and speed up navigation).
- Antivirus filters, AntiPopUp, etc.
- Access control via proxy login and password.
- Time-based access control.
To do this, open Synaptic, and click on Search
and enter squid
to find the modules related to Squid.
Consult the documentation for each module and the Squid manual for more information.
See also: Installing an easy HTTP proxy-cache (polipo)