Building & Running Kerberos 5 on Windows ---------------------------------------- This file documents how to build the standalone source distribution of Kerberos 5 on Windows. The MIT Kerberos for Windows distribution contains additional components not present in the Kerberos 5 source code. To build Kerberos 5 on Windows, you will need the Windows SDK (XP SP2 or later) and a version of Perl installed in the command-line path. Current versions of the Windows SDK require the .NET framework to be installed. There are two methods for building a Windows version of Kerberos 5. The traditional method involves starting on a Unix machine and creating a distribution that can be built on Windows. The second method works from the sources that come from the Unix distribution if you have certain Unix-type utilities (see below). 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. 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. To build a release version, you need to define NODEBUG either in the environment or the nmake command-line. DNS Support: To support DNS lookups, you will need to define KRB5_DNS_LOOKUP, KRB5_DNS_LOOKUP_KDC, or KRB5_DNS_LOOKUP_REALMS. When any of the KRB5_DNS_LOOKUP definitions are used, the default build will use the WSHelper library which is part of the Kerberos for Windows (Kfw) distribution. If you are building outside of KfW and wish to build Krb5 with DNS support, you must provide a resolver library whose include files match the Unix resolver library. You will need to define KRB5_NO_WSHELPER, define DNS_INC to point to the include directory for the library and DNS_LIB to library itself. The default is not to support DNS because the build cannot know whether there is a DNS resolver library around for it to use. Traditional Build Method: ------------------------ On the Unix side 1) cd xxx/src # Go to where the source lives 2) make -f Makefile.in kerbsrc.zip # Do some Unix-side configuring # ...and create kerbsrc.zip 3) On the PC side 1) md \krb5 # Create dir where we'll put the tree 2) cd \krb5 3) unzip kerbsrc.zip - or - pkunzip -d kerbsrc.zip 4) nmake [NODEBUG=1] [DNS-options] # Build the sources 5) nmake install [NODEBUG=1] [options] # Copy headers, libs, executables All-Windows Build Method: ------------------------ First, make sure you have sed, gawk, cat, and cp. 1) cd xxx/src # Go to where the source lives 2) nmake -f Makefile.in prep-windows # Create Makefile for Windows 3) nmake [NODEBUG=1] [DNS-options] # Build the sources 4) nmake install [NODEBUG=1] [options] # Copy headers, libs, executables Notes on the install Target: --------------------------- For the install target, you will need to define KRB_INSTALL_DIR to point to the directory where the header, library, and executable files will be installed. You can either define this in the environment or at the nmake command-line. For example: nmake install [NODEBUG=1] KRB_INSTALL_DIR=c:\sdk\krb5 Make sure you create the directory first. Otherwise, nmake will complain. The files will get installed into include, lib, and bin subdirectories. You can then copy the binaries to where ever you want have them (probably somewhere in your path). Running Kerberos 5 Apps: ----------------------- Make sure you have a valid krb5.ini file. That will look just like a Unix krb5.conf file. You can place this file in the same directory as your krb5_32.dll (this will be the bin subdirectory of your install directory, if you did not move the binaries) or in your Windows directory (typically "C:\Windows"). You should then be able to run the applications that are built. Note that Kerberos 5 will not look for the krb5.ini file in your path. 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 krb5_32.dll's dir and Windows directory Default Credentials Cache: - Environment: KRB5CCNAME - Registry Value: ccname - Default: API:krb5cc or FILE:%TEMP%\krb5cc or FILE:\krb5cc 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. This is implemented by krbcc32.dll, which is not included the the krb5-only distribution. Rather, it is part of MIT's Kerberos for Win32 suite. As of the 1.3.2 release, a new cache type, MSLSA:, has been added for use in accessing 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. A user is able to logon to Windows using the Kerberos LSA if the machine is part of a Windows 2000 or Windows 2003 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 2000 or XP support tools in order to obtain the tools: KSETUP.EXE and KTPASS.EXE. 2. Install the Windows 2000 or XP Resource Kit to obtain the tools KERBTRAY.EXE and KLIST.EXE 3. Add Realms and associated KDCs with: *KSETUP /AddKdc []*. If you leave off the DNS SRV records will be used. 4. Specify the password change service host for the realm with: *KSETUP /AddKpasswd * 5. Assign the realm of the local machine with: *KSETUP /SetRealm * where realm must be all upper case. 6. Assign the local machine's password with: *KSETUP /SetComputerPassword * 7. Specify the capabilities of the Realm KDC with: *KSETUP /SetRealmFlags [ ...]* where flags may be *None, SendAddress, TcpSupported, Delegate, *and *NcSupported*, 8. Map principal names to local accounts with: *KSETUP /MapUser * 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) 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.