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+@c $Id: misc.texi,v 1.13 2003/03/30 21:30:59 lha Exp $
+
+@node Things in search for a better place, Kerberos 4 issues, Setting up a realm, Top
+@chapter Things in search for a better place
+
+@section Making things work on Ciscos
+
+Modern versions of Cisco IOS has some support for authenticating via
+Kerberos 5. This can be used both by having the router get a ticket when
+you login (boring), and by using Kerberos authenticated telnet to access
+your router (less boring). The following has been tested on IOS
+11.2(12), things might be different with other versions. Old versions
+are known to have bugs.
+
+To make this work, you will first have to configure your router to use
+Kerberos (this is explained in the documentation). A sample
+configuration looks like the following:
+
+@example
+aaa new-model
+aaa authentication login default krb5-telnet krb5 enable
+aaa authorization exec krb5-instance
+kerberos local-realm FOO.SE
+kerberos srvtab entry host/router.foo.se 0 891725446 4 1 8 012345678901234567
+kerberos server FOO.SE 10.0.0.1
+kerberos instance map admin 15
+@end example
+
+This tells you (among other things) that when logging in, the router
+should try to authenticate with kerberised telnet, and if that fails try
+to verify a plain text password via a Kerberos ticket exchange (as
+opposed to a local database, RADIUS or something similar), and if that
+fails try the local enable password. If you're not careful when you
+specify the `login default' authentication mechanism, you might not be
+able to login at all. The `instance map' and `authorization exec' lines
+says that people with `admin' instances should be given `enabled' shells
+when logging in.
+
+The numbers after the principal on the `srvtab' line are principal type,
+time stamp (in seconds since 1970), key version number (4), keytype (1 ==
+des), key length (always 8 with des), and then the key.
+
+To make the Heimdal KDC produce tickets that the Cisco can decode you
+might have to turn on the @samp{encode_as_rep_as_tgs_rep} flag in the
+KDC. You will also have to specify that the router can't handle anything
+but @samp{des-cbc-crc}. This can be done with the @samp{del_enctype}
+command of @samp{kadmin}.
+
+This all fine and so, but unless you have an IOS version with encryption
+(available only in the U.S) it doesn't really solve any problems. Sure
+you don't have to send your password over the wire, but since the telnet
+connection isn't protected it's still possible for someone to steal your
+session. This won't be fixed until someone adds integrity to the telnet
+protocol.
+
+A working solution would be to hook up a machine with a real operating
+system to the console of the Cisco and then use it as a backwards
+terminal server.
+
+@section Making things work on Transarc/OpenAFS AFS
+
+@subsection How to get a KeyFile
+
+@file{ktutil -k AFSKEYFILE:KeyFile get afs@@MY.REALM}
+
+or you can extract it with kadmin
+
+@example
+kadmin> ext -k AFSKEYFILE:/usr/afs/etc/KeyFile afs@@My.CELL.NAME
+@end example
+
+You have to make sure you have a @code{des-cbc-md5} encryption type since that
+is the key that will be converted.
+
+@subsection How to convert a srvtab to a KeyFile
+
+You need a @file{/usr/vice/etc/ThisCell} containing the cellname of you
+AFS-cell.
+
+@file{ktutil copy krb4:/root/afs-srvtab AFSKEYFILE:/usr/afs/etc/KeyFile}.
+
+If keyfile already exists, this will add the new key in afs-srvtab to
+KeyFile.
+
+@section Using 2b tokens with AFS
+
+@subsection What is 2b ?
+
+2b is the name of the proposal that was implemented to give basic
+Kerberos 5 support to AFS in rxkad. Its not real Kerberos 5 support
+since it still uses fcrypt for data encryption and not Kerberos
+encryption types.
+
+Its only possible (in all cases) to do this for DES encryption types because
+only then the token (the AFS equivalent of a ticket) will be be smaller
+than the maximum size that can fit in the token cache in
+OpenAFS/Transarc client. Its so tight fit that some extra wrapping on the ASN1/DER encoding is removed from the Kerberos ticket.
+
+2b uses a Kerberos 5 EncTicketPart instead of a Kerberos 4 ditto for
+the part of the ticket that is encrypted with the service's key. The
+client doesn't know what's inside the encrypted data so to the client it doesn't matter.
+
+To differentiate between Kerberos 4 tickets and Kerberos 5 tickets 2b
+uses a special kvno, 213 for 2b tokens and 255 for Kerberos 5 tokens.
+
+Its a requirement that all AFS servers that support 2b also support
+native Kerberos 5 in rxkad.
+
+@subsection Configuring Heimdal to use 2b tokens
+
+Support for 2b tokens are turned on for specific principals by adding
+them to the string list option @code{[kdc]use_2b} in the kdc's
+@file{krb5.conf} file.
+
+@example
+[kdc]
+ use_2b = @{
+ afs@@SU.SE = yes
+ afs/it.su.se@@SU.SE = yes
+ @}
+@end example
+
+@subsection Configuring AFS clients
+
+There is no need to configure AFS clients. The only software that
+needs to be installed/upgrade is a Kerberos 5 enabled @file{afslog}.
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