Provided by: dacs_1.4.38a-2build1_amd64 bug


       dacs.readme - DACS README


       This file is part of the DACS suite.

       After reviewing this document, it will be beneficial to look at these important documents:

       ·   for a brief description of this release, and possibly last minute updates, please
           refer to README[1]

       ·   for a technical overview of the system, including a description of command line flags
           common to most DACS programs, please see dacs(1)[2]

       ·   for information about licensing, please refer to LICENSE[3]

       ·   for information about installation, please refer to dacs.install(7)[4]

       ·   for the Quick Start tutorial, please refer to dacs.quick(7)[5]

       ·   for important release notes, please visit

           NO WARRANTY
           This software is provided by Dss "as is" and any express or implied warranties,
           including, but not limited to, the implied warranties of merchantability, fitness for
           a particular purpose, or non-infringement, are disclaimed. in no event shall dss be
           liable for any direct, indirect, incidental, special, exemplary, or consequential
           damages (including, but not limited to, procurement of substitute goods or services;
           loss of use, data, or profits; or business interruption) however caused and on any
           theory of liability, whether in contract, strict liability, or tort (including
           negligence or otherwise) arising in any way out of the use of this software, even if
           advised of the possibility of such damage.

   DACS At a Glance
       DACS is:

       ·   a light-weight, open source single sign-on system;

       ·   a flexible and powerful attribute- and role-based access control system;

       ·   a set of feature-rich authentication methods;

       ·   an Apache[6] 2.2 and 2.4 module and suite of CGI programs;

       ·   able to apply coarse-grained access control to web service requests made using
           standard web browsers;

       ·   able to provide fine-grained access control functionality to almost any program or

       ·   a collection of web services that can provide access control and identity management
           functionality to your middleware;

       ·   a C/C++ toolkit for building new authentication and access control functionality into
           programs, whether web-based or not;

       ·   for Unix-type platforms, such as GNU/Linux, macOS, and FreeBSD.

       For developers, DACS makes access control functionality available through the command
       line, allowing scripts (Perl, PHP, shell, etc.) to make data-driven access control
       decisions rather than program-driven ones. This can be used completely independently of
       the web functionality and without dealing with run-time configuration of DACS. Please see
       dacscheck(1)[7].  DACS also provides web services from which single sign-on systems can be

       For web sites, DACS can help manage access to web resources in many situations, whether
       you have just one web server, several web servers at one site, or many web servers spread
       across the Internet. You may find it to be useful simply as a universal authentication
       mechanism for a single Apache server or as a full-fledged, single sign-on multi-server
       identity management and access control system.

           If you are interested in dacscheck(1)[7] or the general-purpose DACS utilities (e.g.,
           dacshttp(1)[8], sslclient(1)[9]) but are not interested in web services or Apache,
           refer to the instructions in dacs.install(7)[4].

       The DACS home page is at  DACS was hosted as a SourceForge[10] project
       at, but that has not been used since 2013.

   Supported Platforms
       DACS is currently developed and tested:

       ·   with Apache[6] 2.2.31 and 2.4.23 (2.0.X releases, which were once supported, are now
           deprecated and untested)

       ·   on platforms:

           ·   FreeBSD[11] 10.3 and 11.0 (amd64)

           ·   CentOS[12] 7.2 (x86_64, Linux 3.10, built from Red Hat Enterprise Linux[13] 7)

           ·   macOS Sierra[14] 10.12 (Intel Core i7, x86_64)

       ·   using GCC 4.9 (and newer), and on some platforms, recent Clang/LLVM compilers

       ·   using recent Firefox, Safari, Chrome, and Internet Explorer browsers

       FreeBSD 10.3 is the primary development platform. For this reason, references to Unix
       manual pages throughout the DACS documentation cite the FreeBSD documentation. This should
       not matter much if you are using a different platform, but keep this in mind.

       Most DACS installations are on Linux or FreeBSD platforms. Support for macOS is
       comparatively recent.

           ·   When building DACS for use with Apache 2.2, you will probably need to specify the
               --with-apache-apr flag, and perhaps other Apache-related flags, to configure.

           ·   Apache 1.3 and 2.0 are not supported (please refer to the FAQ[15]).

           ·   DACS has not been tested with Apache 2.1.

   Other Platforms
       DACS is not officially supported on platforms other than those described above. Recent
       releases have built and worked correctly on other platforms, but because we do not have
       ready access to them, or due to lack of interest, we no longer test on them.

       Up to and including version 1.4.25, DACS was tested and used on Solaris 10[16]
       (OpenSolaris[17] 2008.11, SunOS 5.11, x86[18]).  Solaris is no longer supported. Early
       versions of DACS were used on Solaris 8 (SPARC) and Solaris 10 (SPARC) platforms. A wide
       variety of build, install, and run-time problems were encountered with third-party
       packages on the OpenSolaris and SPARC platforms. Depending on which third-party software
       your DACS configuration requires, or if you are prepared to try older versions of
       third-party software or devote extra effort, you may have some success running DACS on
       these platforms, but in general we cannot recommend using these platforms for DACS in
       production settings and they are no longer officially supported. Comments specific to
       Solaris remain in the DACS documentation but will likely be removed in a future release,
       as will configuration and build capabilities.

       Earlier releases of DACS compiled and (mostly) installed cleanly on WinXP/Cygwin[19] 1.7.5
       and later with GCC 4.3, but starting with DACS 1.4.26, Cygwin[19] is no longer used for
       testing DACS. Comments specific to Cygwin that remain in the DACS documentation will
       likely be removed in a future release, as will configuration and build capabilities.
       Regarding Cygwin and earlier versions of DACS:

       ·   mod_auth_dacs does not build as a shared module

       ·   there were problems building Expat 2.0.0 from source (2.0.1 is ok)

       ·   only limited testing has been performed on this platform

       ·   you can't execute src/config.nice; copy it to some other filename and execute that

       ·   when doing "make install", try the username and group "Administrators" or
           "Administrator" when prompted if you don't know what else to use (the install
           procedure should use those names as defaults

       We expect that DACS will also run on other varieties of Unix and with other browsers. No
       testing is done with very old browsers, however. We would appreciate reports of problems
       encountered while building or running DACS on unofficial platforms so that we can address
       portability issues and support these platforms better.

       Please read this section carefully!

            1. After obtaining a DACS release, please verify all checksums for the file you
               downloaded. Do not use a download if any checksum for it does not match. Checksums
               are posted at immediately after a new release is

               OpenSSL's dgst command can be used to compute checksums; for example,

                   % openssl dgst -md5 dacs-1.4.32.tgz
                   % openssl dgst -sha1 dacs-1.4.32.tgz

            2. Improper installation, configuration, or use of DACS may leave your system open to
               various kinds of attacks and exploits.

               Many other systems and software components, including Apache and OpenSSL, can also
               compromise system security if not properly installed, configured, and
               administered; they give similar admonishments. Please take appropriate care.

               A DACS administrator ought to have some experience with Apache configuration
               (including its authentication and access control directives, and building httpd),
               and basic knowledge of security issues on the installation platform.

            3. The security of DACS depends on the security of the underlying operating system,
               third party software, build, installation, and configuration parameters, human
               factors, and more. In particular, ensure that file ownership and modes are
               appropriate for run-time accessible DACS configuration and data files (dacs.conf,
               site.conf, encryption keys, access control rules, group files, etc.).

            4. Users of your DACS-wrapped services are responsible for maintaining the secrecy of
               information used to sign on (such as passwords) and authentication and
               authorization information sent to them by DACS (such as HTTP cookies). Spyware,
               and browser modifications or improper settings, may compromise security - DACS
               cannot prevent improper use or intentional misuse.

            5. After access is granted to a resource, DACS does nothing to stop a user from
               redistributing whatever is returned by the web server. Therefore, strictly
               speaking, DACS is neither a copyright enforcement system nor is it a Digital
               Rights Management (DRM) system[20], although it may be possible to apply DACS in
               those domains.  DACS does have the ability to force a user to view and acknowledge
               a copyright notice or license, however.

            6. Making routine backup copies of your current DACS configuration and data files is
               strongly encouraged. A procedure should be established for periodically creating
               copies of your DACS installation and keeping them in a secure, off-site location.
               This is especially important for encryption keys and account files, which cannot
               be recreated if lost.

            7. Please review Section 15 ("Security Considerations") of RFC 2616[21].

            8. Be sure to check for new releases of DACS regularly. New releases may address
               important bugs and security issues, so keeping your installation current is
               important. You can subscribe to email notifications[22].

               You should likewise stay alert to new releases of third-party packages that your
               install of DACS uses.

            9. Note that, because of the enormous number of combinations of platforms, versions,
               third-party packages, build options, run-time options, and so on, not every
               possible DACS deployment that can be created and enabled is actually built or
               tested. This is presumably true for nearly every large software package but it's
               worth emphasizing. Therefore, make sure you test carefully before putting your
               DACS deployment into production and after making changes to it.

           10. Reiterating, test carefully after making changes to your DACS configuration. In
               particular, make sure that new access control rules and user authentication work
               as you expect.

           11. For DACS to be a secure system, all communication between DACS and its users,
               components, and middleware must take place over a secure connection (typically
               using SSL/TLS and the HTTPS[23] method) to safeguard account names, passwords,
               DACS credentials, and so on.  DACS does not require secure network connections,
               however, and can function without them in situations where a lower standard of
               security is acceptable. See SECURE_MODE[24].

               Note that if a client connects from an insecure subnet, various man-in-the-middle
               attacks[25] are possible, even when it appears that SSL/TLS is being used (for
               example, see sslstrip[26]).

           12. In the event of an emergency situation that might be related to DACS, you may, of
               course, stop all Apache processes. It is sufficient to make dacs.conf inaccessible
               to Apache, however, whether by renaming the file, changing its ownership, or
               changing its permissions. (Or, you may make the DACS web services unavailable
               using the same methods.) All DACS web services must be able to read dacs.conf, so
               this will effectively turn DACS off. More selective ways of limiting access are
               available, such as through the revocation list.

           13. DACS depends mainly on OpenSSL[27], a third-party package that you need to obtain
               separately, for cryptographic functionality. Some library functions provided by
               your operating system (such as crypt(3)[28]) are also used.

           14. It is strongly recommended that the Network Time Protocol (NTP, RFC 1305[29]) or
               equivalent be used on any host that runs DACS commands or web services. A sudden,
               large change to a system's clock while DACS is operational may have undesirable
               effects and should be avoided. In particular, setting the system's clock backward
               must be avoided as it may make the system more vulnerable to attack, such as by
               effectively extending the lifetime of sensitive data or the validity period of
               certain operations.

           15. System administrators should take appropriate steps to ensure that Domain Name
               System (DNS, RFC 1035[30]) lookups are secure.

           16. If you are deploying DACS as part of a publicly accessible web site, consider
               including a notification on your site that it may issue cookies. This is commonly
               mentioned in a site's "Privacy" or "Security" page.  DACS may not function as
               expected if a user's browser has disabled cookies or will not accept them; in
               particular, the single sign-on feature generally requires that users' browsers
               accept cookies.

           17. The DACS distribution may include code, features, or functionality that is not
               described in the distribution's documentation, or is described as untested,
               partially implemented, or deprecated, or is accompanied by a warning. Such code,
               features, or functionality is subject to change or removal without notice and
               should not be used.

           DACS MAY INCLUDE ITS OWN CRYPTOGRAPHIC FUNCTIONS and may therefore fall under certain
           import, export, and/or use restrictions in other parts of the world, even though DACS
           is developed, maintained, and officially distributed from Canada.

           Export and/or import and/or use of strong cryptography software, providing
           cryptography hooks, or merely communicating technical details about cryptographic
           software is illegal in some parts of the world. YOU ARE STRONGLY ADVISED to pay close
           attention to any laws that may apply when you import, export, or use DACS, or even
           communicate about it. We are not liable for any violations you make - it is your
           responsibility. For additional information, see the Crypto Law Survey[31].

   Release Information
       Information about DACS releases, including the latest release, is provided in the Version
       Guide[32] and on the Download and Release Information page.

       To programmatically determine the latest version of DACS and obtain a direct link for
       downloading, you may invoke, which returns a
       simple text document comprised of name/value pairs.

       Stability, backward compatibility, portability across supported platforms, and keeping up
       to date with respect to third-party support packages are now the primary goals of DACS 1.4
       releases. A top priority is to fix all known bugs between releases and improve the

       Please consult the DACS web site for information on upcoming releases.

           Because DACS is security software, we strongly recommend that you upgrade to the
           newest release as soon as you are able.

       Upgrading is neither a difficult nor a time consuming procedure most times. Sometimes an
       incompatible change in DACS will require you to change a DACS configuration file, but this
       should not be difficult to do and we will try to advise you of such changes.

       The DACS 1.4 releases contain a great many changes and improvements, some incompatible
       with earlier releases of DACS. If you are upgrading from DACS 1.3.2 or another older
       release, you will need to become familiar with these changes. You must manually convert
       your old DACS configuration files to the new format, for example. You should not find
       upgrading to be a difficult or time consuming task.

           Making backup copies of your DACS installation immediately prior to upgrading is
           strongly recommended.

       Some features available in earlier versions of DACS are not available in this release, but
       will be provided as soon as possible.

       Note that DACS 1.4 may not interoperate with prior releases.

       We aim to avoid making any backward incompatible changes within the DACS 1.4.x releases.

   Add-on Features
       Some features of DACS may be implemented by third parties or as custom extensions. They
       may be included with the open source DACS distribution (and therefore fall under the open
       source LICENSE[3]), or are provided separately. The dacsversion[33] command and
       dacs_version[34] web service indicate whether add-ons are enabled (present) in a
       particular installation of DACS; look for +addons or addons="enabled" from the former, and
       ENABLE_ADDONS=1 from the latter.

       While add-ons may provide new capabilities, they should not alter the syntax or semantics
       of capabilities shared with the base DACS distribution.

       Once installed and configured, DACS requires very little administration.

           At higher logging levels, DACS log files can become large quite quickly. You should
           therefore arrange for them to be rotated regularly (e.g., using newsyslog(8)[35]). A
           built-in log rotation feature is being considered for DACS.

       If you're creating DACS log files that have names based on their date of creation, to
       expire/rotate/compress them you might periodically run the find(1)[36] command to identify
       old logs. For example, the command

           % find /usr/local/dacs/logs -type f -a -mtime 2 -a -exec gzip {} \;

       will compress any files in the log directory that haven't been modified for at least 24

       There are also Apache modules available to do the rotation:



   Related Software
       A variety of other software and resources for DACS can be found in the dacs-contrib[37]
       project at SourceForge[10].

       The DACS Java Library (DJL)
           The DJL is being developed to support the use of DACS in Java client applications. It
           implements Java wrapper classes for selected DACS services, and provides an HTTP
           client through which DACS services may be accessed and DACS credentials obtained and

       The FedAdmin Web Application
           FedAdmin is an administrator console for managing the configuration of DACS
           federations and jurisdictions. It is deployed in a servlet container such as Tomcat,
           but must be accessed via an Apache+DACS proxy and deployed under a dedicated FEDADMIN
           DACS application jurisdiction.

           FedAdmin implements partial coverage of the most common DACS configuration tasks,
           including viewing federation and jurisdiction configuration directives, adding and
           deleting local DACS users, and creating, editing, and deleting ACL rules.

       An array of technical support is available from DSS[38]. Please see the support page[39]
       for details.  DACS development, maintenance, and free support is made possible in part by
       customers that purchase technical support packages or contract for customizations (most of
       which then become available to all free of charge).

   Known Problems
       There are a few defects in the DACS 1.4 releases that administrators should be aware of.
       These are not likely to be addressed in the near future.

        1. If the HTTP data stream is compressed or encrypted (other than via SSL/TLS), DACS will
           not be able to access POST arguments and you should use the mod_auth_dacs module
           directive "SetDACSAuthPostBuffer 0".

        2. In general, DACS does not support IPv6 addresses.

        3. The group management service and group distribution utilities have not be tested with
           this release of DACS.

        4. The man pages are generated from DocBook XML. The docbook-xsl used to create [nt]roff
           source is incomplete and/or buggy. As a result, the quality of the formatting is
           sometimes poor. You will find the HTML version of the documentation more readable.

        5. Support for internationalization is poor.

        6. Some configuration directives have global scope (i.e., they apply in several contexts)
           when it might be preferable to have context-specific versions of them. For example,
           the algorithm specified by PASSWORD_DIGEST[40] is used for more than one purpose
           within DACS. On the other hand, this reduces the number of directives, and therefore
           helps to contain the complexity of DACS.

   Bugs, Suggestions, and Feedback
       Please see the support page[39] for details.

       Some elements of DACS are less well-travelled than others and users may therefore
       experience problems with them. Please let us know[41] if you encounter bugs.


       dacs(1)[2], dacs.install(7)[4], dacs.quick(7)[5]


       Distributed Systems Software ([38])


       Copyright2003-2016 Distributed Systems Software. See the LICENSE[3] file that accompanies
       the distribution for licensing information.


        1. README

        2. dacs(1)

        3. LICENSE

        4. dacs.install(7)

        5. dacs.quick(7)

        6. Apache

        7. dacscheck(1)

        8. dacshttp(1)

        9. sslclient(1)

       10. SourceForge

       11. FreeBSD

       12. CentOS

       13. Red Hat Enterprise Linux

       14. macOS Sierra

       15. FAQ

       16. Solaris 10

       17. OpenSolaris

       18. x86

       19. Cygwin

       20. Digital Rights Management (DRM) system

       21. RFC 2616

       22. subscribe to email notifications

       23. HTTPS

       24. SECURE_MODE

       25. man-in-the-middle attacks

       26. sslstrip

       27. OpenSSL

       28. crypt(3)

       29. RFC 1305

       30. RFC 1035

       31. Crypto Law Survey

       32. Version Guide

       33. dacsversion

       34. dacs_version

       35. newsyslog(8)

       36. find(1)

       37. dacs-contrib

       38. DSS

       39. support page


       41. let us know