[How To] Squid and LDAP-authentication from Active Directory

Today many people need to authenticate users to the proxy using accounts created in Active Directory.

For doing this task squid itself must be compiled with support for basic authentication and external groups in LDAP Keys.

--enable-basic-auth-helpers=LDAP --enable-external-acl-helpers=ldap_group

In this example our Active Directory have IP address and our domain in Active Directory is domain.com.

To start let’s create a group named “net” in Active Directory, users added in this group will have access to the internet. Also let’s create any user and add to group “net”

Example: test_inet with password “123456

To work with the directory, we need a user to read out the passwords.
Example: squidreader with password “pass“.

Now check the availability of the catalog with squidreader user

ldapsearch -D "[email protected]" -x -W -b "dc=domain,dc=com" -h

As a result of this command we will get the content of our Active Directory.
Now let’s check the work of the work components squid. Create a file with a password of the account, which we read (squidreader).
Example it will be /usr/local/etc/squid/adpw.txt

echo pass > /usr/local/etc/squid/adpw.txt

Checking the group:

/usr/local/libexec/squid/squid_ldap_group -R -b "dc=domain,dc=com" -f "(&(sAMAccountName=%v)(memberOf=cn=%a,dc=domain,dc=com))" -D [email protected] -W /usr/local/etc/squid/adpw.txt

As a query enter a string in the format:
username group
In this case:
test_inet net

The answer is either “OK” or “ERR”. If we have everything working correctly, the answer would be “OK”.

Next check the authentication:

/usr/local/libexec/squid/squid_ldap_auth -R -D [email protected] -W /usr/local/etc/squid/adpw.txt -b "dc=domain,dc=com" -f "sAMAccountName=%s"

As a query enter a string in the format:

username password

The answers are the same as in past cases.
Enter the test_inet 123456” and waiting for an answer “OK”.

Configuring the squid


auth_param basic program /usr/local/libexec/squid/squid_ldap_auth -R -D [email protected] -W /usr/local/etc/squid/adpw.txt -b "dc=domain,dc=com" -f "sAMAccountName=%s"

External group:

external_acl_type ldap_users %LOGIN /usr/local/libexec/squid/squid_ldap_group -R -b "dc=domain,dc=com" -f "(&(cn=%v)(memberOf=cn=%a,dc=domain,dc=com ))" -D [email protected] -W /usr/local/etc/squid/adpw.txt

The parameter %LOGIN is describeing the outer group, before testing for entry into this group, the user must be authenticated.

Description of the ACL:

acl ad_net external ldap_users net

Well, and finally giving access to the internet:

http_access allow ad_net

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