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squid configuration

Squid Block any Domain Name Accessing the Internet

Q. How do I block any website accessing the Internet using squid proxy server?

A. You can simply use squid ACL to block access to any web site. There are 3 steps:

#1. Create a text file with blocked domain name list such as baddomain1.com, mail.yahoo.com, gmail.com and so on

#2. Define Acl

#3. Restart squid

First, create a file called /etc/squid/blocked.domains.acl
# vi /etc/squid/blocked.domains.acl
Append domain names,

Save and close the file. Open squid.conf file:
# vi /etc/squid/squid.conf
Create acl called blockeddomain:
acl blockeddomain dstdomain "/etc/squid/blocked.domains.acl"
Deny http access, enter:
http_access deny blockeddomain
Close and save the file. Restart squid proxy server:
# /etc/init.d/squid restart

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Squid NTLM authentication configuration using ntlm_auth

Q. How do I configure squid for NTLM authentication?

A. You need to use squid ntlm_auth helper tool. It o allow external access to Winbind’s NTLM authentication function. ntlm_auth uses winbind to access the user and authentication data for a domain.

Make sure winbindd is working

winbindd is a daemon that provides a number of services to the Name Service Switch capability found in most modern C libraries, to arbitary applications via PAM and ntlm_auth and to Samba itself. If you are not sure about winbindd, refer to official Samba documentation for configuration.

Configure squid for NTLM authentication

Open squid configuration file – squid.conf, enter:
# vi squid.conf
Append following configuration directive:
auth_param ntlm program /usr/lib/squid/ntlm_auth --helper-protocol=squid-2.5-ntlmssp
auth_param basic program /usr/lib/squid/ntlm_auth --helper-protocol=squid-2.5-basic
auth_param basic children 5
auth_param basic realm Squid proxy-caching web server
auth_param basic credentialsttl 2 hours

To setup ntlm_auth for use by squid 2.5 with group limitation, add:
auth_param ntlm program /usr/lib/squid/ntlm_auth --helper-protocol=squid-2.5-ntlmssp --require-membership-of="WORKGROUP\Domain Users"
auth_param basic program /usr/lib/squid/ntlm_auth --helper-protocol=squid-2.5-basic --require-membership-of="WORKGROUP\Domain Users"
auth_param ntlm children 5
auth_param ntlm max_challenge_reuses 0
auth_param ntlm max_challenge_lifetime 2 minutes

OR You can also pass DOMAIN/PDC name:
auth_param ntlm program /usr/lib/squid/ntlm_auth DOMAINNAME/PDC
auth_param ntlm children 5
auth_param ntlm max_challenge_reuses 0
auth_param ntlm max_challenge_lifetime 2 minutes

Now add ACL configuration for ntlm_auth helper
acl ntlm_users proxy_auth REQUIRED
http_access allow ntlm_users
http_access deny all

Save and close the file. Restart Squid:
# /etc/init.d/squid restart
For more information:

Updated for accuracy.

Squid Deny Users Accessing a Website

How do I deny a user accessing particular website? For example deny access to a website called foo.com.
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