path: root/src/windows/README

	       Building & Running Kerberos 5 on Windows
	       ----------------------------------------

This file documents how to build MIT Kerberos for Windows.
The MIT Kerberos for Windows distribution contains additional components
not present in the Unix krb5 distribution, most notably the
MIT Kerberos Ticket Manager application.

To build Kerberos 5 on Windows, you will need the Windows SDK (XP SP3
or later), VisualStudio (2010 Professional), a version of Perl, and some
common Unix utilities such as sed/awk/cp/cat installed in the
command-line path.  To build an MSI installer, you will additionally
need the Windows Installer XML (WiX) toolkit, and to ensure that
the HTML Help Compiler (hhc.exe) and the WiX tools are in your command-line
path.  WiX version 3.5 is verified to work with this codebase; WiX 3.7
and newer are incompatible with this codebase.  Visual Studio 2012 and
the Windows SDK 8 introduce some changes which alter the Kerberos build
procedure slightly (noted where appropriate).

The Unix utilities can be obtained via the Utilities and SDK for UNIX-based
Aplications, which may be enabled as a Windows feature and then the
components installed.  Note that the Windows nmake will not find the
SUA awk utility in the path unless it is named awk.exe; the permissions
on the utility may need correcting if awk.exe is created as a copy of
the original awk.

There is a version of perl available through the SUA, but it is not
sufficient to build krb5.  An external perl such as Strawberry Perl
or ActiveState Perl is necessary.

The krb5 source tree may be obtained either directly on the Windows
machine with a native git client cloning the krb5 public mirror
at https://github.com/krb5/krb5.git or on a separate (Unix) machine
and copied over, such as from a VM host onto a Windows VM.
The kerbsrc.zip method is no longer supported.

After the Windows SDK is installed, you should be able to invoke an
SDK command prompt via the start menu (All Programs -> Microsoft
Windows SDK vX.Y -> Windows SDK X.Y Command Prompt).  Within this
window, you can change the build target using the setenv command; run
"setenv /?" or see the Windows SDK documentation for details.  At the
current time, Kerberos 5 can only be built for the x64 target if the
host platform is also 64-bit, because it compiles and runs programs
during the build.  The Windows SDK version 8 does not provide an SDK
command prompt; the "Developer Command Prompt for VS2012" or "Visual Studio
Command Prompt" must be used instead.  Accordingly, there is no setenv script
to configure the build environment for different target architectures; the
"vcvarsall.bat" script provided by Visual Studio serves this function.

IMPORTANT NOTE: By default, the sources are built with debug
information and linked against the debug version of the Microsoft C
Runtime library, which is not found on most Windows systems unless
they have development tools, and requires a separate license to distribute.
To build a release version, you need to define NODEBUG either in the
environment or the nmake command-line and use setenv to enter a release
build environment with "setenv /release" (when using Windows SDK versions
lower than 8).  Debug information in the compiled binaries and libraries
may be retained by defining DEBUG_SYMBOL in the environment or on the nmake
command line.


Building the code and installer
------------------------

First, make sure you have sed, (g)awk, cat, and cp.
You must also define KRB_INSTALL_DIR either in the environment or
on the command line (for nmake install).  If you are proceeding to build
the MSI installer, this directory should be a temporary staging area in or
near your build tree.  The directory must exist before nmake install
is run.  The 64-bit installer provides 32-bit libraries, so a 32-bit build
and install must be performed before the 64-bit build.

 1) set CPU=i386                        # Get 32-bit target in environment
 2) set KRB_INSTALL_DIR=\path\to\dir    # Where bin/include/lib lives
 3) setenv /x86 [/release]              # Tell nmake to target 32-bit
    (with Visual Studio 2012, use "vcvarsall.bat x86")
 4) cd xxx/src                          # Go to where the source lives
 5) nmake -f Makefile.in prep-windows   # Create Makefile for Windows
 6) nmake [NODEBUG=1]                   # Build the sources
 7) nmake install [NODEBUG=1]           # Copy headers, libs, executables
 8) cd windows\installer\wix            # Go to where the installer source is
 9) nmake                               # Build the installer
10) rename kfw.msi kfw32.msi            # Save the 32-bit installer
11) set CPU=AMD64                       # Proceed to the 64-bit build
12) setenv /x64 [/release]              # Must set both CPU and nmake env
    ("vcvarsall.bat amd64" for Visual Studio 2012)
13) cd ..\..\..                         # Back to the sources
14) nmake clean                         # Clean up the 32-bit objects
15) nmake [NODEBUG=1]                   # Build the sources for 64-bit
16) nmake install [NODEBUG=1]           # Copy 64-bit lib/executables
17) cd windows\installer\wix            # Back to the installer source
18) nmake clean                         # Remove 32-bit leavings
19) nmake                               # Build the 64-bit installer
20) rename kfw.msi kfw64.msi            # And name it usefully


Running Kerberos 5 Apps:
-----------------------

Make sure you have a valid krb5.ini file.
By default, an empty krb5.ini is installed in CSIDL_COMMON_APPDATA
(that is, %SystemDrive%\ProgramData\MIT\Kerberos5\ on newer-than-XP).
(ProgramData is a hidden folder.)  You may need to customize it with
settings for your site, but since DNS lookups are enabled for locating
KDCs, many sites will not need further customization.  The file format is
identical to that of a Unix krb5.conf file.


krb5.ini File:
-------------

WARNING: Despite its name, this is not a Windows .ini file.
Therefore, do not try to use any .ini tools, including the Windows API
or any installer tools to manipulate this file.  Its format is subtly
different from Windows .ini files!


Controlling the Kerberos 5 Run-Time Environment:
-----------------------------------------------

The Kerberos 5 configuration file and credentials cache can be
controlled with environment variables and registry settings.  The
environment variable for a particular setting always takes precedence.
Next in precedence comes the setting in the registry under
HKEY_CURRENT_USER\Software\MIT\Kerberos5.  Then comes the registry
setting under HKEY_LOCAL_MACHINE\Software\MIT\Kerberos5.  If none of
those are found, a default value is used.

Configuration File:
- Environment: KRB5_CONFIG
- Registry Value: config
- Default: looks in the user's AppData directory, the machine's ProgramData
  directory, krb5_32.dll's dir and Windows directory

Default Credentials Cache:
- Environment: KRB5CCNAME
- Registry Value: ccname
- Default: API:


Credentials Cache:
-----------------

In addition to standard FILE: (disk file) and MEMORY: (in-process
non-shared memory) Windows supports the API: cache type, which is a
shared memory cache.  Kerberos for Windows also has access to an
MSLSA: cache type, which directly accesses the Microsoft Kerberos
Logon Session credentials cache.  The MSLSA: cache is available when the
user logon is performed using Kerberos either to an Active Directory Domain
or a non-Microsoft KDC; the ms2mit and mit2ms utilities can also be used
to interact with it, though there are some limitations.

A user is able to logon to Windows using the Kerberos LSA if the machine
is part of a Windows Active Directory domain or if the machine has been
configured to authenticate to a non-Microsoft KDC such as MIT.
The instructions for configuring a Windows 2000 XP workstation to
authenticate to a non-Microsoft KDC are documented in TechNet somewhere.
In brief:

  1. Install the Windows support tools in order to obtain KSETUP.EXE
     and KTPASS.EXE.
  2. Install the Windows Resource Kit to obtain KERBTRAY.EXE and KLIST.EXE
  3. Add Realms and associated KDCs with: *KSETUP /AddKdc <realm>
     [<kdcname>]*.  If you leave off the <kdcname> DNS SRV records will
     be used.
  4. Specify the password change service host for the realm with:
     *KSETUP /AddKpasswd <realm> <Kpwdhost>*
  5. Assign the realm of the local machine with: *KSETUP /SetRealm
     <realm>* where realm must be all upper case.   
  6. Assign the local machine's password with: *KSETUP
     /SetComputerPassword <Password>
     *
  7. Specify the capabilities of the Realm KDC with: *KSETUP
     /SetRealmFlags <realm> <flag> [<flag> ...]* where flags may be
     *None, SendAddress, TcpSupported, Delegate, *and *NcSupported*,
  8. Map principal names to local accounts with: *KSETUP /MapUser
     <principal> <account>*

On the MIT KDC, you must then create service principals using the "Password" 
assigned to the machine.  So far the minimum list of principals required appear 
to be for a machine named "mymachine" in the realm "EXAMPLE.COM" with a 
domain name of "example.com":

   * host/mymachine@EXAMPLE.COM
   * host/mymachine.example.com@EXAMPLE.COM
   * cifs/mymachine@EXAMPLE.COM
   * cifs/mymachine.example.com@EXAMPLE.COM

There may very well be other serivces for which principals must be created depending 
on what services are being executed on the machine.

It is very important to note that while you can successfully log into a Windows 
workstation by authenticating to the KDC without creating a host key; the logon 
session you receive will not be a Kerberos Logon Session.  There will be no Kerberos 
principal and no LSA cache to access.

The result of a real KSETUP configuration looks like this:

   [C:\4\4NT]ksetup
   default realm = KRB5.COLUMBIA.EDU (external)
   ATHENA.MIT.EDU:
           kdc = kerberos.mit.edu
           kdc = kerberos-1.mit.edu
           kdc = kerberos-2.mit.edu
           kdc = kerberos-3.mit.edu
           Realm Flags = 0x0 none
   CC.COLUMBIA.EDU:
           kdc = kerberos.cc.columbia.edu
           Realm Flags = 0x0 none
   GRAND.CENTRAL.ORG:
           kdc = penn.central.org
           kdc = grand-opening.mit.edu
           Realm Flags = 0x0 none
   KRB5.COLUMBIA.EDU:
           kdc = yclept.kermit.columbia.edu
           Realm Flags = 0x0 none
   OPENAFS.ORG:
           kdc = virtue.openafs.org
           Realm Flags = 0x0 none
   Mapping jaltman@KRB5.COLUMBIA.EDU to jaltman.
   Mapping jaltman@CC.COLUMBIA.EDU to jaltman.
   Mapping jaltman@ATHENA.MIT.EDU to jaltman.
   Mapping all users (*) to a local account by the same name (*).

The MSLSA: credential cache relies on the ability to extract the entire
Kerberos ticket including the session key from the Kerberos LSA.  In an
attempt to increase security Microsoft has begun to implement a feature
by which they no longer export the session keys for Ticket Getting Tickets.
This has the side effect of making them useless to the MIT krb5 library
when attempting to request additional service tickets.

This new feature has been seen in Windows 2003 Server, Windows 2000 Server SP4,
and Windows XP SP2.  We assume that it will be implemented in all future
Microsoft operating systems supporting the Kerberos SSPI.  Microsoft does work
closely with MIT and has provided a registry key to disable this new feature.
On server platforms the key is specified as:

  HKLM\SYSTEM\CurrentControlSet\Control\Lsa\Kerberos\Parameters
    AllowTGTSessionKey = 0x01 (DWORD)

On workstation platforms the key is specified as: 

  HKLM\SYSTEM\CurrentControlSet\Control\Lsa\Kerberos
    AllowTGTSessionKey = 0x01 (DWORD)

The Kerberos for Windows installer automatically sets this key on installation
and unsets it on uninstall, allowing the MSLSA: cache type to be used.

It has been noted that the Microsoft Kerberos LSA does not provide enough 
information within its KERB_EXTERNAL_TICKET structure to properly construct
the Client Principal simply by examining a single ticket. From the MSDN
Library:

  ClientName 
    KERB_EXTERNAL_NAME structure that contains the client name in the ticket. 
    This name is relative to the current domain. 

  DomainName 
    UNICODE_STRING that contains the name of the domain that corresponds to 
    the ServiceName member. This is the domain that issued the ticket. 

  TargetDomainName 
    UNICODE_STRING that contains the name of the domain in which the ticket is
    valid. For an interdomain ticket, this is the destination domain. 

  AltTargetDomainName 
    UNICODE_STRING that contains a synonym for the destination domain. Every 
    domain has two names: a DNS name and a NetBIOS name. If the name returned 
    in the ticket is different from the name used to request the ticket (the 
    Kerberos Key Distribution Center (KDC) may do name mapping), this string 
    contains the original name. 

Unfortunately, there is no field here which contains the domain of the client.
In order for the krb5_ccache to properly report the client principal name, the 
client principal name is constructed by utilizing the ClientName and DomainName
fields of the Initial TGT associated with the Kerberos LSA credential cache.
To disable the use of the TGT info and instead simply use the "DomainName" field
of the current ticket define one of the following registry keys depending on
whether the change should be system global or just for the current user.

   HKLM\Software\MIT\Kerberos5\
      PreserveInitialTicketIdentity = 0x0 (DWORD)

   HKCU\Software\MIT\Kerberos5\
      PreserveInitialTicketIdentity = 0x0 (DWORD)

GSSAPI Sample Client:
---------------------

The GSS API Sample Client provided in this distribution is compatible with the
gss-server application built on Unix/Linux systems.  This client is not compatible
with the Platform SDK/Samples/Security/SSPI/GSS/ samples which Microsoft has been
shipping as of January 2004.  Revised versions of these samples are available upon 
request to krbdev@mit.edu.  

More Information:
----------------

For more information, please read the Kerberos 5 documentation in
the doc directory of the distribution.