How to configure squid Proxy Server to authenticate users In Linux

we are going to learn to put authentication in squid proxy server. Each user will have to give a valid username and password in order to use the proxy server.

We will configure authentication using the NCSA module.

NOTE: I assume that you have got squid server already configured and running. (Please read How to configure squid proxy server)

1) Create a NCSA password file using to store usernames and password for basic authentication.

[root@client ~]# touch /etc/squid/password

/etc/squid/password is blank file, you can change its name and location as per your need.

2) Next, we can add users using the htpasswd command:

[root@server ~]# htpasswd /etc/squid/password sam
New password: 
Re-type new password: 
Adding password for user sam
[root@server ~]# 

/etc/squid/password will now have the authentication details for user sam, similarly we can add more users in same file.

3) Now open the squid configuration file /etc/squid/squid.conf and insert or modify these lines (on top of every line i have written a comment stating what it does, if you don't, do not write them) :

[root@server ~]# vi /etc/squid/squid.conf
#This line defines the file holding the authentication details and also the program to check those details
auth_param basic program /usr/lib/squid/ncsa_auth /etc/squid/password

#Define the maximum number of child process to spawn for authentication
auth_param basic children 5

#user will see this message "Squid proxy-caching web server" in authentication box
auth_param basic realm Squid proxy-caching web server

#time to live after a successful authentication
auth_param basic credentialsttl 2 hours

#to make username case insensitive
auth_param basic casesensitive off

4) Now, add the following ACL in the same file in acl section and also allow this ACL:

#this rule will match and allow all the users having a successful authentication
acl valid_users proxy_auth REQUIRED
http_access allow valid_users

Save and exit the file.

5) Restart the squid service

[root@server ~]# service squid restart

6) Thats it, Now configure your browser to use this proxy and try to open any webpage, the authentication box will pop up.