1@c $Id: win2k.texi 21991 2007-10-19 13:28:07Z lha $ 2 3@node Windows 2000 compatability, Programming with Kerberos, Kerberos 4 issues, Top 4@comment node-name, next, previous, up 5@chapter Windows 2000 compatability 6 7Windows 2000 (formerly known as Windows NT 5) from Microsoft implements 8Kerberos 5. Their implementation, however, has some quirks, 9peculiarities, and bugs. This chapter is a short summary of the things 10that we have found out while trying to test Heimdal against Windows 112000. Another big problem with the Kerberos implementation in Windows 122000 is that the available documentation is more focused on getting 13things to work rather than how they work, and not that useful in figuring 14out how things really work. 15 16This information should apply to Heimdal @value{VERSION} and Windows 172000 Professional. It's of course subject to change all the time and 18mostly consists of our not so inspired guesses. Hopefully it's still 19somewhat useful. 20 21@menu 22* Configuring Windows 2000 to use a Heimdal KDC:: 23* Inter-Realm keys (trust) between Windows 2000 and a Heimdal KDC:: 24* Create account mappings:: 25* Encryption types:: 26* Authorisation data:: 27* Quirks of Windows 2000 KDC:: 28* Useful links when reading about the Windows 2000:: 29@end menu 30 31@node Configuring Windows 2000 to use a Heimdal KDC, Inter-Realm keys (trust) between Windows 2000 and a Heimdal KDC, Windows 2000 compatability, Windows 2000 compatability 32@comment node-name, next, precious, up 33@section Configuring Windows 2000 to use a Heimdal KDC 34 35You need the command line program called @command{ksetup.exe} which is available 36in the file @file{SUPPORT/TOOLS/SUPPORT.CAB} on the Windows 2000 Professional 37CD-ROM. This program is used to configure the Kerberos settings on a 38Workstation. 39 40@command{Ksetup} store the domain information under the registry key: 41@code{HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\LSA\Kerberos\Domains}. 42 43Use the @command{kadmin} program in Heimdal to create a host principal in the 44Kerberos realm. 45 46@example 47unix% kadmin 48kadmin> ank --password=password host/datan.example.com 49@end example 50 51The name @samp{datan.example.com} should be replaced with DNS name of 52the workstation. 53 54You must configure the workstation as a member of a workgroup, as opposed 55to a member in an NT domain, and specify the KDC server of the realm 56as follows: 57@example 58C:> ksetup /setdomain EXAMPLE.COM 59C:> ksetup /addkdc EXAMPLE.COM kdc.example.com 60@end example 61 62Set the machine password, i.e.@: create the local keytab: 63@example 64C:> ksetup /SetComputerPassword password 65@end example 66 67The password used in @kbd{ksetup /setmachpassword} must be the same 68as the password used in the @kbd{kadmin ank} command. 69 70The workstation must now be rebooted. 71 72A mapping between local NT users and Kerberos principals must be specified. 73You have two choices. First: 74 75@example 76C:> ksetup /mapuser user@@MY.REALM nt_user 77@end example 78 79This will map a user to a specific principal; this allows you to have 80other usernames in the realm than in your NT user database. (Don't ask 81me why on earth you would want that@enddots{}) 82 83You can also say: 84@example 85C:> ksetup /mapuser * * 86@end example 87The Windows machine will now map any user to the corresponding principal, 88for example @samp{nisse} to the principal @samp{nisse@@MY.REALM}. 89(This is most likely what you want.) 90 91@node Inter-Realm keys (trust) between Windows 2000 and a Heimdal KDC, Create account mappings, Configuring Windows 2000 to use a Heimdal KDC, Windows 2000 compatability 92@comment node-name, next, precious, up 93@section Inter-Realm keys (trust) between Windows 2000 and a Heimdal KDC 94 95See also the Step-by-Step guide from Microsoft, referenced below. 96 97Install Windows 2000, and create a new controller (Active Directory 98Server) for the domain. 99 100By default the trust will be non-transitive. This means that only users 101directly from the trusted domain may authenticate. This can be changed 102to transitive by using the @command{netdom.exe} tool. @command{netdom.exe} 103can also be used to add the trust between two realms. 104 105You need to tell Windows 2000 on what hosts to find the KDCs for the 106non-Windows realm with @command{ksetup}, see @xref{Configuring Windows 2000 107to use a Heimdal KDC}. 108 109This needs to be done on all computers that want enable cross-realm 110login with @code{Mapped Names}. @c XXX probably shouldn't be @code 111 112Then you need to add the inter-realm keys on the Windows KDC@. Start the 113Domain Tree Management tool (found in Programs, Administrative tools, 114Active Directory Domains and Trusts). 115 116Right click on Properties of your domain, select the Trust tab. Press 117Add on the appropriate trust windows and enter domain name and 118password. When prompted if this is a non-Windows Kerberos realm, press 119OK. 120 121Do not forget to add trusts in both directions (if that's what you want). 122 123If you want to use @command{netdom.exe} instead of the Domain Tree 124Management tool, you do it like this: 125 126@example 127netdom trust NT.REALM.EXAMPLE.COM /Domain:EXAMPLE.COM /add /realm /passwordt:TrustPassword 128@end example 129 130You also need to add the inter-realm keys to the Heimdal KDC. Make sure 131you have matching encryption types (DES, Arcfour and AES in case of Longhorn) 132 133Another issue is salting. Since Windows 2000 does not seem to 134understand Kerberos 4 salted hashes you might need to turn off anything 135similar to the following if you have it, at least while adding the 136principals that are going to share keys with Windows 2000. 137 138@example 139[kadmin] 140 default_keys = v5 v4 141@end example 142 143So remove v4 from default keys. 144 145What you probably want to use is this: 146 147@example 148[kadmin] 149 default_keys = des-cbc-crc:pw-salt arcfour-hmac-md5:pw-salt 150@end example 151 152@c XXX check this 153@c It is definitely not supported in base 2003. I haven't been able to 154@c get SP1 installed here, but it is supposed to work in that. 155 156Once that is also done, you can add the required inter-realm keys: 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 165Do not forget to reboot before trying the new realm-trust (after 166running @command{ksetup}). It looks like it might work, but packets are 167never sent to the non-Windows KDC. 168 169@node Create account mappings, Encryption types, Inter-Realm keys (trust) between Windows 2000 and a Heimdal KDC, Windows 2000 compatability 170@comment node-name, next, precious, up 171@section Create account mappings 172 173Start the @code{Active Directory Users and Computers} tool. Select the 174View menu, that is in the left corner just below the real menu (or press 175Alt-V), and select Advanced Features. Right click on the user that you 176are going to do a name mapping for and choose Name mapping. 177 178Click on the Kerberos Names tab and add a new principal from the 179non-Windows domain. 180 181@c XXX check entry name then I have network again 182This adds @samp{authorizationNames} entry to the users LDAP entry to 183the Active Directory LDAP catalog. When you create users by script you 184can add this entry instead. 185 186@node Encryption types, Authorisation data, Create account mappings, Windows 2000 compatability 187@comment node-name, next, previous, up 188@section Encryption types 189 190Windows 2000 supports both the standard DES encryptions (@samp{des-cbc-crc} and 191@samp{des-cbc-md5}) and its own proprietary encryption that is based on MD4 and 192RC4 that is documented in and is supposed to be described in 193@file{draft-brezak-win2k-krb-rc4-hmac-03.txt}. New users will get both 194MD4 and DES keys. Users that are converted from a NT4 database, will 195only have MD4 passwords and will need a password change to get a DES 196key. 197 198@node Authorisation data, Quirks of Windows 2000 KDC, Encryption types, Windows 2000 compatability 199@comment node-name, next, previous, up 200@section Authorisation data 201 202The Windows 2000 KDC also adds extra authorisation data in tickets. 203It is at this point unclear what triggers it to do this. The format of 204this data is only available under a ``secret'' license from Microsoft, 205which prohibits you implementing it. 206 207A simple way of getting hold of the data to be able to understand it 208better is described here. 209 210@enumerate 211@item Find the client example on using the SSPI in the SDK documentation. 212@item Change ``AuthSamp'' in the source code to lowercase. 213@item Build the program. 214@item Add the ``authsamp'' principal with a known password to the 215database. Make sure it has a DES key. 216@item Run @kbd{ktutil add} to add the key for that principal to a 217keytab. 218@item Run @kbd{appl/test/nt_gss_server -p 2000 -s authsamp 219@kbd{--dump-auth}=@var{file}} where @var{file} is an appropriate file. 220@item It should authenticate and dump for you the authorisation data in 221the file. 222@item The tool @kbd{lib/asn1/asn1_print} is somewhat useful for 223analysing the data. 224@end enumerate 225 226@node Quirks of Windows 2000 KDC, Useful links when reading about the Windows 2000, Authorisation data, Windows 2000 compatability 227@comment node-name, next, previous, up 228@section Quirks of Windows 2000 KDC 229 230There 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 231as a Kerberos 4 compatible salt---does not work, as far as we can tell 232from out experiments and users' reports. Therefore, you have to make 233sure you keep around keys with all the different types of salts that are 234required. Microsoft have fixed this issue post Windows 2003. 235 236Microsoft seems also to have forgotten to implement the checksum 237algorithms @samp{rsa-md4-des} and @samp{rsa-md5-des}. This can make Name 238mapping (@pxref{Create account mappings}) fail if a @samp{des-cbc-md5} key 239is used. To make the KDC return only @samp{des-cbc-crc} you must delete 240the @samp{des-cbc-md5} key from the kdc using the @kbd{kadmin 241del_enctype} command. 242 243@example 244kadmin del_enctype lha des-cbc-md5 245@end example 246 247You should also add the following entries to the @file{krb5.conf} file: 248 249@example 250[libdefaults] 251 default_etypes = des-cbc-crc 252 default_etypes_des = des-cbc-crc 253@end example 254 255These configuration options will make sure that no checksums of the 256unsupported types are generated. 257 258@node Useful links when reading about the Windows 2000, , Quirks of Windows 2000 KDC, Windows 2000 compatability 259@comment node-name, next, previous, up 260@section Useful links when reading about the Windows 2000 261 262See also our paper presented at the 2001 Usenix Annual Technical 263Conference, available in the proceedings or at 264@uref{http://www.usenix.org/publications/library/proceedings/usenix01/freenix01/westerlund.html}. 265 266There are lots of texts about Kerberos on Microsoft's web site, here is a 267short list of the interesting documents that we have managed to find. 268 269@itemize @bullet 270 271@item Step-by-Step Guide to Kerberos 5 (krb5 1.0) Interoperability: 272@uref{http://www.microsoft.com/technet/prodtechnol/windows2000serv/howto/kerbstep.mspx}. 273Kerberos GSS-API (in Windows-eze SSPI), Windows as a client in a 274non-Windows KDC realm, adding unix clients to a Windows 2000 KDC, and 275adding cross-realm trust (@pxref{Inter-Realm keys (trust) between Windows 2000 276and a Heimdal KDC}). 277 278@item Windows 2000 Kerberos Authentication: 279@uref{www.microsoft.com/technet/prodtechnol/windows2000serv/deploy/confeat/kerberos.mspx}. 280White paper that describes how Kerberos is used in Windows 2000. 281 282@item Overview of Kerberos: 283@uref{http://support.microsoft.com/support/kb/articles/Q248/7/58.ASP}. 284Links to useful other links. 285 286@c @item Klist for Windows: 287@c @uref{http://msdn.microsoft.com/library/periodic/period00/security0500.htm}. 288@c Describes where to get a klist for Windows 2000. 289 290@item Event logging for Kerberos: 291@uref{http://support.microsoft.com/support/kb/articles/Q262/1/77.ASP}. 292Basically it say that you can add a registry key 293@code{HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\Kerberos\Parameters\LogLevel} 294with value DWORD equal to 1, and then you'll get logging in the Event 295Logger. 296 297@c @item Access to the Active Directory through LDAP: 298@c @uref{http://msdn.microsoft.com/library/techart/kerberossamp.htm} 299 300@end itemize 301 302Other useful programs include these: 303 304@itemize @bullet 305@item pwdump2 306@uref{http://www.bindview.com/Support/RAZOR/Utilities/Windows/pwdump2_readme.cfm}@end itemize 307