Squid NTLM authentication configuration using ntlm_auth

NTLM (NT LAN Manager) is a proprietary Microsoft security protocol that can be used to authenticate users on a network. Squid, a popular open-source web proxy, can be configured to use NTLM authentication by leveraging the "ntlm_auth" helper program.

To configure Squid for NTLM authentication using the "ntlm_auth" helper, you will need to follow these steps:

1. Install the "samba-winbind" package, which includes the "ntlm_auth" program.

2. Edit the Squid configuration file ("/etc/squid/squid.conf") and add the following lines to enable NTLM authentication:

auth_param ntlm program /usr/local/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp
auth_param ntlm children 10
auth_param ntlm keep_alive on

3. Define an access control list (ACL) to specify which users or groups are allowed to access the proxy. For example:

acl authenticated_users proxy_auth REQUIRED

4. Use the "http_access" directive to allow or deny access to the proxy based on the ACL you defined. For example:

http_access allow authenticated_users

5. Restart Squid to apply the changes.

It's worth noting that the NTLM authentication configuration may vary depending on your specific requirements and the version of Squid you are using. You may also need to configure your clients to use NTLM authentication when connecting to the proxy.