path: root/README

                           remctl release 2.13
            (remote authenticated command execution with ACLs)

                   Originally written by Anton Ushakov
         Currently maintained by Russ Allbery <rra@stanford.edu>

  Copyright 2002, 2003, 2004, 2005, 2006, 2007, 2008 Board of Trustees,
  Leland Stanford Jr. University.  This software is distributed under a
  BSD-style license.  Please see the file LICENSE in the distribution for
  more information.

BLURB

  remctl is a client/server application that supports remote execution of
  specific commands, using Kerberos v5 GSS-API for authentication.
  Authorization is controlled by a configuration file and ACL files and
  can be set separately for each command, unlike with rsh.  remctl is like
  a Kerberos-authenticated simple CGI server, or a combination of Kerberos
  rsh and sudo without most of the features and complexity of either.

DESCRIPTION

  remctl is a client/server application that supports remote execution of
  specific commands, using Kerberos v5 GSS-API for authentication.  Which
  commands a given user can execute is controlled by a configuration file
  and ACL files and can be easily tightly limited, unlike with rsh.

  remctld is very similar to a CGI server that uses a different network
  protocol than HTTP and always does strong authentication before
  executing the desired command.  Alternately, you can think of it as a
  very simple combination of Kerberos rsh and sudo, without most of the
  features of both but with simpler authorization.

  This package was developed to replace the use of sysctl, another package
  that allowed remote code execution with Kerberos (v4) authentication.
  sysctl embedded Tcl and allowed for arbitrary Tcl code to be run, but at
  Stanford we found that in practice all we did with it was execute
  programs on the host system.  remctl is a Kerberos v5 equivalent that
  does only the portions we actually needed.

  Both C and Java clients and servers are provided, as well as Perl, PHP,
  and Python bindings for the C client library.  For more information
  about the Java client, see java/README.  For more information about the
  PHP bindings, see php/README.  For more information about the Python
  bindings, see python/README.

  Complete protocol documentation is available in docs/protocol.html.
  Also present, as docs/design.html, is the original design document (now
  somewhat out of date).

REQUIREMENTS

  The remctld server and the standard client are written in C and require
  a C compiler to build.  Both will build against either MIT Kerberos or
  Heimdal (tested with Heimdal 0.6 and later).  remctl will also build
  against the Kerberos GSS-API implementation shipped with AIX 5.2.

  To build the remctl client for Windows, the Microsoft Windows SDK for
  Windows Vista and the MIT Kerberos for Windows SDK are required, along
  with a Microsoft Windows build environment (probably Visual Studio).
  remctl has only been tested with the 3.2.1 MIT Kerberos for Windows SDK.
  To run the resulting binary, MIT Kerberos for Windows must be installed
  and configured.  The client has been tested on Windows XP and Vista and
  should work on Windows 2000 and up.  The server is not supported on
  Windows.

  To build the Perl bindings for the C client library, you will need Perl
  5.6.0 or later.  To run the full test suite for the Perl bindings, the
  Perl modules Test::More and Test::Pod must be installed.  Test::More
  comes with Perl 5.8 and later.  Test::Pod currently must be installed
  separately, but the POD tests will be skipped without interfering with
  the rest of the tests if it's not installed.  The Perl bindings have not
  been tested in Windows.

  To build the PHP bindings for the C client library, you will need PHP
  5.x (only tested with 5.2) and phpize, plus any other programs that
  phpize requires.

  To build the Python bindings for the C client library, you will need
  Python 2.3 or later (primarily tested with Python 2.5).  The Python
  bindings have not been tested on Windows.

  A Java client and Java server are available in the java subdirectory,
  but they are not integrated into the normal build or built by default.
  There is a basic Makefile in that directory that may require some
  tweaking.  It currently requires the Sun Java JDK (1.4.2, 5, or 6).

  To run the test suite, you will need Test::Pod as described above.  The
  test suite will also need to be able to build to 127.0.0.1 on port 11119
  and 14444 to run test network server programs.  In order to fully test
  remctl, you will also need to create a keytab for a valid Kerberos
  principal in your local realm; see tests/data/README for more
  information.

  If you change the Automake files and need to regenerate Makefile.in, you
  will need Automake 1.10 or later.  If you change configure.ac or any of
  the m4 files it includes and need to regenerate configure or
  config.h.in, you will need Autoconf 2.61 or later.

INSTALLATION (UNIX)

  You can build and install remctl with the standard commands:

      ./configure
      make
      make install

  The last step will probably have to be done as root.  By default, remctl
  installs itself under /usr/local; you can change that path by passing
  the --prefix=PATH argument to configure.

  To also build the Perl bindings for the libremctl client library, pass
  the --enable-perl option to configure.  The Perl module build is handled
  by the normal Perl extension build system, and therefore will be built
  with compiler flags defined by your Perl installation and installed into
  your local Perl module directory regardless of the --prefix argument to
  configure.  To change this, you will need to run perl on Makefile.PL in
  the perl subdirectory of the build tree with appropriate options and
  rebuild the module after running make and before running make install.

  To also build the remctl PECL extension for PHP, pass the --enable-php
  option to configure.  The PHP PECL module build is handled by the normal
  PHP extension build system and therefore will be installed into your
  local PHP module directory.  The configure script will look for phpize
  on your PATH by default; if it's in some other directory, set the PHPIZE
  environment variable to the full path or set it on the configure command
  line.  The configure script for the PECL extension will be run during
  the build instead of during configure.  This is unfortunately apparently
  unavoidable given how the PECL build system works.

  To also build the Python bindings for the libremctl client library, pass
  the --enable-python option to configure.  The Python module build is
  handled by the normal Python extension build system, and therefore will
  be installed into your local Python module directory regardless of the
  --prefix argument to configure.  To change this, you will need to run
  python setup.py install by hand in the python directory with whatever
  options you want to use.

  Normally, configure will use krb5-config to determine the flags to use
  to compile with your Kerberos GSS-API libraries.  If krb5-config isn't
  found, it will look for the standard Kerberos libraries in locations
  already searched by your compiler.  If the the krb5-config script first
  in your path is not the one corresponding to the Kerberos libraries you
  want to use or if your Kerberos libraries and includes aren't in a
  location searched by default by your compiler, you need to specify
  --with-gssapi=PATH:

      ./configure --with-gssapi=/usr/pubsw

  You can also individually set the paths to the include directory and the
  library directory with --with-gssapi-include and --with-gssapi-lib.  You
  may need to do this if Autoconf can't figure out whether to use lib,
  lib32, or lib64 on your platform.  Note that these settings aren't used
  if a krb5-config script is found.

  To specify a particular krb5-config script to use, either set the
  KRB5_CONFIG environment variable or pass it to configure like:

      ./configure KRB5_CONFIG=/path/to/krb5-config

  To not use krb5-config and force library probing even if there is a
  krb5-config script on your path, set KRB5_CONFIG to a nonexistent path:

      ./configure KRB5_CONFIG=/nonexistent

  remctl will automatically build with GPUT support if the GPUT header and
  library are found.  You can pass --with-gput to configure to specify the
  root directory where GPUT is installed, or set the include and library
  directories separately with --with-gput-include and --with-gput-lib.

  You can build remctl in a different directory from the source if you
  wish.  To do this, create a new empty directory, cd to that directory,
  and then give the path to configure when running configure.  Everything
  else should work as above.

  Usage information is available in the manual pages which will be
  installed with remctl.  You will need to set up a remctl.conf file for
  the server; see docs/remctl.conf for an example.  The default location
  for remctl.conf is <prefix>/etc, but can be changed with the
  --sysconfdir flag to configure.

  You can pass the --enable-reduced-depends flag to configure to try to
  minimize the shared library dependencies encoded in the binaries.  This
  omits from the link line all the libraries included solely because the
  Kerberos libraries depend on them and instead links the programs only
  against libraries whose APIs are called directly.  This will only work
  with shared Kerberos libraries and will only work on platforms where
  shared libraries properly encode their own dependencies (such as Linux).
  It is intended primarily for building packages for Linux distributions
  to avoid encoding unnecessary shared library dependencies that make
  shared library migrations more difficult.  If none of the above made any
  sense to you, don't bother with this flag.

  The Java client and server aren't integrated with the regular build
  system.  For information on building and installing them, see
  java/README.

INSTALLATION (Windows)

  First, install the Microsoft Windows SDK for Windows Vista if you have
  not already.  This is a free download from Microsoft for users of
  "Genuine Microsoft Windows."  The vcvars32.bat environment provided by
  Visual Studio may work as an alternative, but has not been tested.

  Next, install the MIT Kerberos for Windows SDK, available for download
  from http://web.mit.edu/kerberos/www/dist/index.html.  remctl has been
  tested with version 3.2.1 but should hopefully work with later versions.

  Then, follow these steps:

  1. Run the InitEnv.cmd script included with the Windows SDK with
     parameters "/xp /release".

  2. Run the configure.bat script, giving it as an argument the location
     of the Kerberos for Windows SDK.  For example, if you installed the
     KfW SDK in "c:\KfW SDK", you should run:

         configure "c:\KfW SDK"

  3. Run nmake to start compiling.  You can ignore the warnings.

  If all goes well, you will have remctl.exe and remctl.dll.  The latter
  is a shared library used by the client program.  It exports the same
  interface as the UNIX libremctl library.

TESTING

  remctl comes with an extensive test suite which you can run after
  building remctl with:

      make check

  In order to do more than limited tests of the low-level routines, you
  should first create a keytab for testing use containing the key for a
  principal in your local domain.  See tests/data/README for instructions
  on what to create and where to place the files.

  If a test case fails, please run that individual test case directly and
  send me the output when reporting the problem.  Note that on
  particularly slow or loaded systems, you may see intermittant failures
  from the server/streaming test because it's timing-sensitive.

HOMEPAGE AND SOURCE REPOSITORY

  The remctl web page at:

      http://www.eyrie.org/~eagle/software/remctl/

  will always have the current version of this package, the current
  documentation, and pointers to any additional resources.

  remctl is maintained using Git.  You can access the current source by
  cloning the repository at:

      git://git.eyrie.org/kerberos/remctl.git

  or view the repository via the web at:

      http://git.eyrie.org/?p=kerberos/remctl.git

THANKS

  To Anton Ushakov for the original design document, much of the version
  one protocol design, and the initial implementation.

  To Roland Schemers for extensive review of the initial code and protocol
  and help with the original Java client.

  To Romain LENGLET for the idea and code for examples/rsh-wrapper.

  To Thomas Kula for testing of remctl 2.0 and later versions on NetBSD
  and Heimdal and for the Python bindings.

  To Ralf Wildenhues for help in getting make check to work with builddir
  != srcdir builds.

  To Darren Patterson and Digant Kasundra for contributions to the RPM
  spec file and testing on Red Hat.

  To Jonathan Kollasch for the initial IPv6 patch and for identifying all
  of the places the code was making IPv4 assuptions.

  To Andrew Mortensen for the initial -F and -k flag support for remctld.

  To Alf Wachsmann for catching inaccuracies in the Perl documentation.

  To Jeffrey Hutzelman and Chaskiel Grundman for testing with Heimdal 0.6
  and teaching me a great deal about GSS-API flags and the security issues
  that surround them.

  To Marcus Watts for testing and various bug fixes, lots of improvements
  to the standalone server mode, and fixes for the Perl API.  Marcus also
  rewrote the Java client, adding support for protocol version two and a
  server implementation.

  To Sandor Sklar for testing multiple patches for the remctl build on AIX
  5.2 and providing an account so that I could investigate test suite
  issues.

  To Matthew Loar for the Windows port of the remctl client.

  To Andrew Mortensen for the initial remctl PECL extension for PHP and
  for general code formatting comments and a reminder to free malloc'd
  memory in the Python bindings.

  To Jeffrey Hutzelman for adding the framework for ACL method support and
  implementing the file, princ, deny, and gput schemes, as well as lots of
  testing and portability bug reports.

  To Timothy G. Abbott for suggesting additional restrictions on the names
  of files read when processing an include of a directory.