Provided by: squid-openssl_5.6-1ubuntu3_amd64 bug


       ext_ldap_group_acl - Squid LDAP external acl group helper

       Version 2.18


       ext_ldap_group_acl -b base-DN -f filter [ options ] [ server [ ':' port ] | URI ] ...


       ext_ldap_group_acl allows Squid to connect to a LDAP directory to authorize users via LDAP
       groups.  LDAP options  are  specified  as  parameters  on  the  command  line,  while  the
       username(s)  and  group(s)  to  be  checked  against  the  LDAP directory are specified on
       subsequent lines of input to the helper, one username/group pair per line separated  by  a

       As  expected  by the external_acl_type construct of Squid, after specifying a username and
       group followed by a new line, this helper will produce either OK or ERR on  the  following
       line to show if the user is a member of the specified group.

       The  program  operates  by searching with a search filter based on the users user name and
       requested group, and if a match is found it is determined that the  user  belongs  to  the


       -a never|always|search|find
                   When to dereference aliases. Defaults to 'never'

                   never dereference aliases (default), always dereference aliases, only during a
                   search or only to find the base object

       -b basedn   REQUIRED.  Specifies the base DN under which the groups are located.

       -B basedn   Specifies the base DN under which the users are located (if different)

       -c connect_timeout
                   Specify timeout used when connecting to LDAP servers (requires  Netscape  LDAP
                   API libraries)

       -d          Debug  mode  where  each  step  taken will get reported in detail.  Useful for
                   understanding what goes wrong if the result is not what was expected.

       -D binddn -w password
                   The DN and password to bind as while performing searches. Required if the LDAP
                   directory does not allow anonymous searches.

                   As  the password needs to be printed in plain text in your Squid configuration
                   and will be sent on the command line to the helper 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  file  or
                   extracts the password used from a process listing.

       -D binddn -W secretfile
                   The  DN  and  the  name  of  a  file  containing the password to bind as while
                   performing searches.

                   Less insecure version of the former parameter pair with  two  advantages:  The
                   password  does not occur in the process listing, and the password is not being
                   compromised if someone gets the squid configuration file without  getting  the

       -E certpath Enable LDAP over SSL (requires Netscape LDAP API libraries)

       -f filter   LDAP  search  filter  used to search the LDAP directory for any matching group
                   memberships.   In the filter %u will be replaced by the user name  (or  DN  if
                   the -F or -u options are used) and %g by the requested group name.

       -F filter   LDAP search filter used to search the LDAP directory for any matching users.
                   In the filter %s will be replaced by the user name. If %  is  to  be  included
                   literally in the filter then use %%

       -g          Specifies  that  the  first  query  argument  sent to the helper by Squid is a
                   extension to the basedn and will be temporarily added in front of  the  global
                   basedn for this query.

       -h ldapserver
                   Specify the LDAP server to connect to

       -H ldapuri  Specify  the  LDAP  server  to  connect  to  by  a LDAP URI (requires OpenLDAP

       -K          Strip Kerberos Realm component from user names (@ separated)

       -p ldapport Specify an alternate TCP port where the LDAP server is listening if other than
                   the default LDAP port 389.

       -P          Use  a  persistent  LDAP connection. Normally the LDAP connection is only open
                   while verifying a users group membership 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 validations. Recommended for larger installations.

       -R          Do not follow referrals

       -s base|one|sub
                   search scope. Defaults to sub

                   base object only,

                   one level below the base object or

                   subtree below the base object

       -S          Strip NT domain name component from user names (/ or \ separated)

       -t search_timeout
                   Specify time limit on LDAP search operations

       -u attr     LDAP attribute used to construct the user DN from the user name  and  base  dn
                   without needing to search for the user.  A maximum of 16 occurrences of %s are

       -v 2|3      LDAP protocol version. Defaults to 3 if not specified.

       -Z          Use TLS encryption


       This helper is intended to be used as an external_acl_type helper in squid.conf .
              external_acl_type ldap_group %LOGIN /path/to/ext_ldap_group_acl ...
              acl group1 external ldap_group Group1
              acl group2 external ldap_group Group2

       NOTE: When constructing search filters it is recommended to first test  the  filter  using
       ldapsearch  to  verify  that  the filter matches what you expect before you attempt to use


       This program was written  by  Flavio  Pescuma  <>  Henrik  Nordstrom

       Based on prior work in squid_ldap_auth by Glen Newton <>

       This manual was written by Henrik Nordstrom <>


        * Copyright (C) 1996-2022 The Squid Software Foundation and contributors
        * Squid software is distributed under GPLv2+ license and includes
        * contributions from numerous individuals and organizations.
        * Please see the COPYING and CONTRIBUTORS files for details.

       This program and documentation is copyright to the authors named above.

       Distributed under the GNU General Public License (GNU GPL) version 2 or later (GPLv2+).


       Questions on the usage of this program can be sent to the Squid Users mailing list <squid->

       Or contact your favorite LDAP list/friend if the question is more  related  to  LDAP  than


       Bug    reports    need    to    be    made    in    English.     See    http://wiki.squid- for details of what you need  to  include  with  your  bug

       Report bugs or bug fixes using

       Report serious security bugs to Squid Bugs <>

       Report   ideas  for  new  improvements  to  the  Squid  Developers  mailing  list  <squid->


       squid(8), basic_ldap_auth(8), ldapsearch(1), GPL(7),
       Your favorite LDAP documentation
       RFC2254 - The String Representation of LDAP Search Filters,
       The Squid FAQ wiki
       The Squid Configuration Manual

                                         30 January 2005                    ext_ldap_group_acl(8)