basic_ldap_auth - LDAP authentication helper for Squid
basic_ldap_auth -b " base DN
" [-u attribute ] [ options
] [ LDAP server name [: port ]| URI ]...
basic_ldap_auth -b " base DN
" -f " LDAP search filter
" [ options ] [ LDAP server name [:
port ]| URI ]...
basic_ldap_auth allows Squid to connect to a LDAP directory
to validate the user name and password of Basic HTTP authentication. LDAP
options are specified as parameters on the command line, while the
username(s) and password(s) to be checked against the LDAP directory are
specified on subsequent lines of input to the helper, one username/password
pair per line separated by a space.
As expected by the basic authentication construct of Squid, after
specifying a username and password followed by a new line, this helper will
produce either OK or ERR on the following line to show if the
specified credentials are correct according to the LDAP directory.
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.
- -f filter
- 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.
Will crash if other % values than %s are used, or if more than
15 %s are used.
- -u userattr
- Specifies the name of the DN attribute that contains the username/login.
Combined with the base DN to construct the users DN when no search filter
is specified ( -f option). Defaults to uid
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 criteria
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).
- -U passwordattr
- Use ldap_compare instead of ldap_simple_bind to verify the
users password. passwordattr is the LDAP attribute storing the
users password.
- -s base|one|sub
- 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 anonymous searches.
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 file.
- -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 secretfile.
- -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 validations. Recommended for larger
installations.
- -O
- Only bind once per LDAP connection. Some LDAP servers do not allow
re-binding as another user after a successful ldap_bind. The use of
this option always opens a new connection for each login attempt. If
combined with the -P option for persistent LDAP connection then the
connection used for searching for the user DN is kept persistent but a new
connection is opened to verify each users password once the DN is
found.
- -R
- Do not follow referrals
- -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.
- -H ldap_uri
- Specify the LDAP server to connect to by LDAP URI (requires OpenLDAP
libraries). Servers can also be specified last on the command line.
- -h ldap_server
- Specify the LDAP server to connect to. Servers can also be specified last
on the command line.
- -p ldap_port
- Specify an alternate TCP port where the LDAP server is listening if other
than the default LDAP port 389. Can also be specified within the server
specification by using servername:port syntax.
- -v 2|3
- LDAP protocol version. Defaults to 3 if not specified.
- -Z
- Use TLS encryption
- -S certpath
- Enable LDAP over SSL (requires Netscape LDAP API libraries)
- -c connect_timeout
- Specify timeout used when connecting to LDAP servers (requires
Netscape LDAP API libraries)
- -t search_timeout
- Specify time limit on LDAP search operations
- -d
- Debug mode where each step taken will get reported in detail. Useful for
understanding what goes wrong if the results is not what is expected.
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:
basic_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
directly from the base DN and login name alone:
basic_ldap_auth -b dc=your,dc=domain -f uid=%s
ldapserver
And similarly if you only want to allow access to users having a
specific attribute
basic_ldap_auth -b dc=your,dc=domain -f
(&(uid=%s)(specialattribute=value)) ldapserver
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:
basic_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 specify a user DN and password to log in as to perform the
searches, as in the following complex Active Directory example
basic_ldap_auth -P -R -b dc=your,dc=domain -D
cn=squid,cn=users,dc=your,dc=domain -w secretsquidpassword -f
(&(userPrincipalName=%s)(objectClass=Person))
activedirectoryserver
NOTE: When constructing search filters it is strongly
recommended to test the filter using ldapsearch before you attempt to
use basic_ldap_auth. This to verify that the filter matches what you
expect.
This program is written by Glenn Newton
<gnewton@wapiti.cisti.nrc.ca> Henrik Nordstrom
<hno@squid-cache.org> This manual is written by Henrik
Nordstrom <hno@squid-cache.org>
* 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-users@lists.squid-cache.org>
Or to your favorite LDAP list/friend if the question is more
related to LDAP than Squid.
Bug reports need to be made in English. See
http://wiki.squid-cache.org/SquidFaq/BugReporting for details of what you
need to include with your bug report.
Report bugs or bug fixes using http://bugs.squid-cache.org/
Report serious security bugs to Squid Bugs
<squid-bugs@lists.squid-cache.org>
Report ideas for new improvements to the Squid Developers
mailing list <squid-dev@lists.squid-cache.org>
squid(8), ldapsearch(1), GPL(7),
Your favorite LDAP documentation.
RFC2254 - The String Representation of LDAP Search Filters,
The Squid FAQ wiki http://wiki.squid-cache.org/SquidFaq
The Squid Configuration Manual http://www.squid-cache.org/Doc/config/