squid_ldap_auth - Squid LDAP authentication helper
squid_ldap_auth -b "base DN" [-u attribute] [options]
squid_ldap_auth -b "base DN" -f "LDAP search filter" [options]
This helper allows Squid to connect to a LDAP directory to validate the
user name and password of Basic HTTP authentication.
The program has two major modes of operation. In the default mode of
operation the users DN is constructed using the base DN and user
attribute. In the other mode of operation a search filter is used to
locate valid user DN's below the base DN.
-b basedn (REQUIRED)
Specifies the base DN under which the users are located.
LDAP search filter to locate the user DN. Required if the users
are in a hierarchy below the base DN, or if the login name is
not what builds the user specific part of the users DN.
The search filter can contain up to 15 occurrences of %s which
will be replaced by the username, as in "uid=%s" for RFC2037
directories. For a detailed description of LDAP search filter
syntax see RFC2254.
Specifies the name of the DN attribute that contains the user-
name/login. Combined with the base DN to construct the users DN
when no search filter is specified (-f option). Defaults to
Note: This can only be done if all your users are located
directly under the same position in the LDAP tree and the login
name is used for naming each user object. If your LDAP tree does
not match these criterias or if you want to filter who are valid
users then you need to use a search filter to search for your
users DN (-f option).
search scope when performing user DN searches specified by the
-f option. Defaults to 'sub'.
base object only, one level below the base object or subtree
below the base object
-D binddn -w password
The DN and password to bind as while performing searches.
Required by the -f flag if the directory does not allow anony-
As the password needs to be printed in plain text in your Squid
configuration it is strongly recommended to use a account with
minimal associated privileges. This to limit the damage in case
someone could get hold of a copy of your Squid configuration
-P Use a persistent LDAP connection. Normally the LDAP connection
is only open while validating a username to preserve resources
at the LDAP server. This option causes the LDAP connection to be
kept open, allowing it to be reused for further user valida-
tions. Recommended for larger installations.
-R do not follow referrals
when to dereference aliases. Defaults to 'never'
never dereference aliases (default), always dereference aliases,
only while searching or only to find the base object
Specify the LDAP server to connect to
Specify an alternate TCP port where the ldap server is listening
if other than the default LDAP port 389.
For directories using the RFC2307 layout with a single domain, all you
need to specify is usually the base DN under where your users are
located and the server name:
squid_ldap_auth -b ou=people,dc=your,dc=domain ldapserver
If you have sub-domains then you need to use a search filter approach
to locate your user DNs as these can no longer be constructed direcly
from the base DN and login name alone:
squid_ldap_auth -b dc=your,dc=domain -f uid=%s ldapserver
And similarily if you only want to allow access to users having a spe-
squid_ldap_auth -b dc=your,dc=domain -f (&(uid=%s)(specialat-
Or if the user attribute of the user DN is "cn" instead of "uid" and
you do not want to have to search for the users then you could use
something like the following example for Active Directory:
squid_ldap_auth -u cn -b cn=Users,dc=your,dc=domain ldapserver
If you want to search for the user DN and your directory does not allow
anonymous searches then you must also use the -D and -w flags to spec-
ify a user DN and password to log in as to perform the searches, as in
the following complex Active Directory example
squid_ldap_auth -p -R -b dc=your,dc=domain -D
cn=squid,cn=users,dc=your,dc=domain -w secretsquidpassword -f
When constructing search filters it is strongly recommended to test the
filter using ldapsearch before you attempt to use squid_ldap_auth. This
to verify that the filter matches what you expect.
This manual page was written by Henrik Nordstrom <firstname.lastname@example.org>
squid_ldap_auth is written by Glenn Newton
<email@example.com> and Henrik Nordstrom <hno@squid-
Will crash if other % values than %s is used in -f, or if more than 15
%s is used.
Any questions on usage can be sent to Squid Users <squid-users@squid-
cache.org>, or to your favorite LDAP list/friend if the question is
more related to LDAP than Squid.
Report bugs or bug-fixes to Squid Bugs <firstname.lastname@example.org> or
ideas for new improvements to Squid Developers <squid-dev@squid-
Your favorite LDAP documentation
RFC2254 - The String Representation of LDAP Search Filters,
Squid LDAP Auth 25 September 2001 squid_ldap_auth(8)