1@c Id 2@c $NetBSD: win2k.texi,v 1.2 2017/01/28 21:31:44 christos Exp $ 3 4 5@node Windows compatibility, Programming with Kerberos, Kerberos 4 issues, Top 6@comment node-name, next, previous, up 7@chapter Windows compatibility 8 9Microsoft Windows, starting from version 2000 (formerly known as Windows NT 5), implements Kerberos 5. Their implementation, however, has some quirks, 10peculiarities, and bugs. This chapter is a short summary of the compatibility 11issues between Heimdal and various Windows versions. 12 13The big problem with the Kerberos implementation in Windows 14is that the available documentation is more focused on getting 15things to work rather than how they work, and not that useful in figuring 16out how things really work. It's of course subject to change all the time and 17mostly consists of our not so inspired guesses. Hopefully it's still 18somewhat useful. 19 20@menu 21* Configuring Windows to use a Heimdal KDC:: 22* Inter-Realm keys (trust) between Windows and a Heimdal KDC:: 23* Create account mappings:: 24* Encryption types:: 25* Authorisation data:: 26* Quirks of Windows 2000 KDC:: 27* Useful links when reading about the Windows:: 28@end menu 29 30@node Configuring Windows to use a Heimdal KDC, Inter-Realm keys (trust) between Windows and a Heimdal KDC, Windows compatibility, Windows compatibility 31@comment node-name, next, precious, up 32@section Configuring Windows to use a Heimdal KDC 33 34You need the command line program called @command{ksetup.exe}. This program comes with the Windows Support Tools, available from either the installation CD-ROM (@file{SUPPORT/TOOLS/SUPPORT.CAB}), or from Microsoft web site. Starting from Windows 2008, it is already installed. This program is used to configure the Kerberos settings on a Workstation. 35 36@command{Ksetup} store the domain information under the registry key: 37@code{HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\LSA\Kerberos\Domains}. 38 39Use the @command{kadmin} program in Heimdal to create a host principal in the 40Kerberos realm. 41 42@example 43unix% kadmin 44kadmin> ank --password=password host/datan.example.com 45@end example 46 47The name @samp{datan.example.com} should be replaced with DNS name of 48the workstation. 49 50You must configure the workstation as a member of a workgroup, as opposed 51to a member in an NT domain, and specify the KDC server of the realm 52as follows: 53@example 54C:> ksetup /setdomain EXAMPLE.COM 55C:> ksetup /addkdc EXAMPLE.COM kdc.example.com 56@end example 57 58Set the machine password, i.e.@: create the local keytab: 59@example 60C:> ksetup /SetComputerPassword password 61@end example 62 63The password used in @kbd{ksetup /setmachpassword} must be the same 64as the password used in the @kbd{kadmin ank} command. 65 66The workstation must now be rebooted. 67 68A mapping between local NT users and Kerberos principals must be specified. 69You have two choices. First: 70 71@example 72C:> ksetup /mapuser user@@MY.REALM nt_user 73@end example 74 75This will map a user to a specific principal; this allows you to have 76other usernames in the realm than in your NT user database. (Don't ask 77me why on earth you would want that@enddots{}) 78 79You can also say: 80@example 81C:> ksetup /mapuser * * 82@end example 83The Windows machine will now map any user to the corresponding principal, 84for example @samp{nisse} to the principal @samp{nisse@@MY.REALM}. 85(This is most likely what you want.) 86 87@node Inter-Realm keys (trust) between Windows and a Heimdal KDC, Create account mappings, Configuring Windows to use a Heimdal KDC, Windows compatibility 88@comment node-name, next, precious, up 89@section Inter-Realm keys (trust) between Windows and a Heimdal KDC 90 91See also the Step-by-Step guide from Microsoft, referenced below. 92 93Install Windows, and create a new controller (Active Directory 94Server) for the domain. 95 96By default the trust will be non-transitive. This means that only users 97directly from the trusted domain may authenticate. This can be changed 98to transitive by using the @command{netdom.exe} tool. @command{netdom.exe} 99can also be used to add the trust between two realms. 100 101You need to tell Windows on what hosts to find the KDCs for the 102non-Windows realm with @command{ksetup}, see @xref{Configuring Windows 103to use a Heimdal KDC}. 104 105This needs to be done on all computers that want enable cross-realm 106login with @code{Mapped Names}. @c XXX probably shouldn't be @code 107 108Then you need to add the inter-realm keys on the Windows KDC@. Start the 109Domain Tree Management tool (found in Programs, Administrative tools, 110Active Directory Domains and Trusts). 111 112Right click on Properties of your domain, select the Trust tab. Press 113Add on the appropriate trust windows and enter domain name and 114password. When prompted if this is a non-Windows Kerberos realm, press 115OK. 116 117Do not forget to add trusts in both directions (if that's what you want). 118 119If you want to use @command{netdom.exe} instead of the Domain Tree 120Management tool, you do it like this: 121 122@example 123netdom trust NT.REALM.EXAMPLE.COM /Domain:EXAMPLE.COM /add /realm /passwordt:TrustPassword 124@end example 125 126You also need to add the inter-realm keys to the Heimdal KDC. But take 127care to the encryption types and salting used for those keys. There should be 128no encryption type stronger than the one configured on Windows side for this 129relationship, itself limited to the ones supported by this specific version of 130Windows, nor any Kerberos 4 salted hashes, as Windows does not seem to 131understand them. Otherwise, the trust will not works. 132 133Here are the version-specific needed information: 134@enumerate 135@item Windows 2000: maximum encryption type is DES 136@item Windows 2003: maximum encryption type is DES 137@item Windows 2003RC2: maximum encryption type is RC4, relationship defaults to DES 138@item Windows 2008: maximum encryption type is AES, relationship defaults to RC4 139@end enumerate 140 141For Windows 2003RC2, to change the trust encryption type, you have to use the 142@command{ktpass}, from the Windows 2003 Resource kit *service pack2*, available 143from Microsoft web site. 144 145@example 146C:> ktpass /MITRealmName UNIX.EXAMPLE.COM /TrustEncryp RC4 147@end example 148 149For Windows 2008, the same operation can be done with the @command{ksetup}, installed by default. 150 151@example 152C:> ksetup /SetEncTypeAttre EXAMPLE.COM AES256-SHA1 153@end example 154 155Once the relationship is correctly configured, you can add the required 156inter-realm keys, using heimdal default encryption types: 157 158@example 159kadmin add krbtgt/NT.REALM.EXAMPLE.COM@@EXAMPLE.COM 160kadmin add krbtgt/REALM.EXAMPLE.COM@@NT.EXAMPLE.COM 161@end example 162 163Use the same passwords for both keys. 164 165And if needed, to remove unsupported encryptions, such as the following ones for a Windows 2003RC2 server. 166 167@example 168kadmin del_enctype krbtgt/REALM.EXAMPLE.COM@@NT.EXAMPLE.COM aes256-cts-hmac-sha1-96 169kadmin del_enctype krbtgt/REALM.EXAMPLE.COM@@NT.EXAMPLE.COM des3-cbc-sha1 170kadmin del_enctype krbtgt/NT.EXAMPLE.COM@@EXAMPLE.COM aes256-cts-hmac-sha1-96 171kadmin del_enctype krbtgt/NT.EXAMPLE.COM@@EXAMPLE.COM des3-cbc-sha1 172@end example 173 174Do not forget to reboot before trying the new realm-trust (after 175running @command{ksetup}). It looks like it might work, but packets are 176never sent to the non-Windows KDC. 177 178@node Create account mappings, Encryption types, Inter-Realm keys (trust) between Windows and a Heimdal KDC, Windows compatibility 179@comment node-name, next, precious, up 180@section Create account mappings 181 182Start the @code{Active Directory Users and Computers} tool. Select the 183View menu, that is in the left corner just below the real menu (or press 184Alt-V), and select Advanced Features. Right click on the user that you 185are going to do a name mapping for and choose Name mapping. 186 187Click on the Kerberos Names tab and add a new principal from the 188non-Windows domain. 189 190@c XXX check entry name then I have network again 191This adds @samp{authorizationNames} entry to the users LDAP entry to 192the Active Directory LDAP catalog. When you create users by script you 193can add this entry instead. 194 195@node Encryption types, Authorisation data, Create account mappings, Windows compatibility 196@comment node-name, next, previous, up 197@section Encryption types 198 199Windows 2000 supports both the standard DES encryptions (@samp{des-cbc-crc} and 200@samp{des-cbc-md5}) and its own proprietary encryption that is based on MD4 and 201RC4 that is documented in and is supposed to be described in 202@file{draft-brezak-win2k-krb-rc4-hmac-03.txt}. New users will get both 203MD4 and DES keys. Users that are converted from a NT4 database, will 204only have MD4 passwords and will need a password change to get a DES 205key. 206 207@node Authorisation data, Quirks of Windows 2000 KDC, Encryption types, Windows compatibility 208@comment node-name, next, previous, up 209@section Authorisation data 210 211The Windows 2000 KDC also adds extra authorisation data in tickets. 212It is at this point unclear what triggers it to do this. The format of 213this data is only available under a ``secret'' license from Microsoft, 214which prohibits you implementing it. 215 216A simple way of getting hold of the data to be able to understand it 217better is described here. 218 219@enumerate 220@item Find the client example on using the SSPI in the SDK documentation. 221@item Change ``AuthSamp'' in the source code to lowercase. 222@item Build the program. 223@item Add the ``authsamp'' principal with a known password to the 224database. Make sure it has a DES key. 225@item Run @kbd{ktutil add} to add the key for that principal to a 226keytab. 227@item Run @kbd{appl/test/nt_gss_server -p 2000 -s authsamp 228@kbd{--dump-auth}=@var{file}} where @var{file} is an appropriate file. 229@item It should authenticate and dump for you the authorisation data in 230the file. 231@item The tool @kbd{lib/asn1/asn1_print} is somewhat useful for 232analysing the data. 233@end enumerate 234 235@node Quirks of Windows 2000 KDC, Useful links when reading about the Windows, Authorisation data, Windows compatibility 236@comment node-name, next, previous, up 237@section Quirks of Windows 2000 KDC 238 239There are some issues with salts and Windows 2000. Using an empty salt---which is the only one that Kerberos 4 supported, and is therefore known 240as a Kerberos 4 compatible salt---does not work, as far as we can tell 241from out experiments and users' reports. Therefore, you have to make 242sure you keep around keys with all the different types of salts that are 243required. Microsoft have fixed this issue post Windows 2003. 244 245Microsoft seems also to have forgotten to implement the checksum 246algorithms @samp{rsa-md4-des} and @samp{rsa-md5-des}. This can make Name 247mapping (@pxref{Create account mappings}) fail if a @samp{des-cbc-md5} key 248is used. To make the KDC return only @samp{des-cbc-crc} you must delete 249the @samp{des-cbc-md5} key from the kdc using the @kbd{kadmin 250del_enctype} command. 251 252@example 253kadmin del_enctype lha des-cbc-md5 254@end example 255 256You should also add the following entries to the @file{krb5.conf} file: 257 258@example 259[libdefaults] 260 default_etypes = des-cbc-crc 261 default_etypes_des = des-cbc-crc 262@end example 263 264These configuration options will make sure that no checksums of the 265unsupported types are generated. 266 267@node Useful links when reading about the Windows, , Quirks of Windows 2000 KDC, Windows compatibility 268@comment node-name, next, previous, up 269@section Useful links when reading about the Windows 270 271See also our paper presented at the 2001 Usenix Annual Technical 272Conference, available in the proceedings or at 273@uref{http://www.usenix.org/publications/library/proceedings/usenix01/freenix01/westerlund.html}. 274 275There are lots of texts about Kerberos on Microsoft's web site, here is a 276short list of the interesting documents that we have managed to find. 277 278@itemize @bullet 279 280@item Step-by-Step Guide to Kerberos 5 (krb5 1.0) Interoperability: 281@uref{http://www.microsoft.com/technet/prodtechnol/windows2000serv/howto/kerbstep.mspx}. 282Kerberos GSS-API (in Windows-eze SSPI), Windows as a client in a 283non-Windows KDC realm, adding unix clients to a Windows 2000 KDC, and 284adding cross-realm trust (@pxref{Inter-Realm keys (trust) between Windows 285and a Heimdal KDC}). 286 287@item Windows 2000 Kerberos Authentication: 288@uref{www.microsoft.com/technet/prodtechnol/windows2000serv/deploy/confeat/kerberos.mspx}. 289White paper that describes how Kerberos is used in Windows 2000. 290 291@item Overview of Kerberos: 292@uref{http://support.microsoft.com/support/kb/articles/Q248/7/58.ASP}. 293Links to useful other links. 294 295@c @item Klist for Windows: 296@c @uref{http://msdn.microsoft.com/library/periodic/period00/security0500.htm}. 297@c Describes where to get a klist for Windows 2000. 298 299@item Event logging for Kerberos: 300@uref{http://support.microsoft.com/support/kb/articles/Q262/1/77.ASP}. 301Basically it say that you can add a registry key 302@code{HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\Kerberos\Parameters\LogLevel} 303with value DWORD equal to 1, and then you'll get logging in the Event 304Logger. 305 306@c @item Access to the Active Directory through LDAP: 307@c @uref{http://msdn.microsoft.com/library/techart/kerberossamp.htm} 308 309@end itemize 310 311Other useful programs include these: 312 313@itemize @bullet 314@item pwdump2 315@uref{http://www.bindview.com/Support/RAZOR/Utilities/Windows/pwdump2_readme.cfm} 316@end itemize 317