(heimdal.info.gz) Cross realm
Info Catalog
(heimdal.info.gz) Encryption types and salting
(heimdal.info.gz) Setting up a realm
(heimdal.info.gz) Transit policy
4.13 Cross realm
================
Suppose you reside in the realm `MY.REALM', how do you authenticate to
a server in `OTHER.REALM'? Having valid tickets in `MY.REALM' allows
you to communicate with Kerberised services in that realm. However, the
computer in the other realm does not have a secret key shared with the
Kerberos server in your realm.
It is possible to share keys between two realms that trust each other.
When a client program, such as `telnet' or `ssh', finds that the other
computer is in a different realm, it will try to get a ticket granting
ticket for that other realm, but from the local Kerberos server. With
that ticket granting ticket, it will then obtain service tickets from
the Kerberos server in the other realm.
For a two way trust between `MY.REALM' and `OTHER.REALM' add the
following principals to each realm. The principals should be
`krbtgt/OTHER.REALM@MY.REALM' and `krbtgt/MY.REALM@OTHER.REALM' in
`MY.REALM', and `krbtgt/MY.REALM@OTHER.REALM' and
`krbtgt/OTHER.REALM@MY.REALM'in `OTHER.REALM'.
In Kerberos 5 the trust can be configured to be one way. So that users
from `MY.REALM' can authenticate to services in `OTHER.REALM', but not
the opposite. In the example above, the `krbtgt/MY.REALM@OTHER.REALM'
then should be removed.
The two principals must have the same key, key version number, and the
same set of encryption types. Remember to transfer the two keys in a
safe manner.
vr$ klist
Credentials cache: FILE:/tmp/krb5cc_913.console
Principal: lha@E.KTH.SE
Issued Expires Principal
May 3 13:55:52 May 3 23:55:54 krbtgt/E.KTH.SE@E.KTH.SE
vr$ telnet -l lha hummel.it.su.se
Trying 2001:6b0:5:1095:250:fcff:fe24:dbf...
Connected to hummel.it.su.se.
Escape character is '^]'.
Waiting for encryption to be negotiated...
[ Trying mutual KERBEROS5 (host/hummel.it.su.se@SU.SE)... ]
[ Kerberos V5 accepts you as ``lha@E.KTH.SE'' ]
Encryption negotiated.
Last login: Sat May 3 14:11:47 from vr.l.nxs.se
hummel$ exit
vr$ klist
Credentials cache: FILE:/tmp/krb5cc_913.console
Principal: lha@E.KTH.SE
Issued Expires Principal
May 3 13:55:52 May 3 23:55:54 krbtgt/E.KTH.SE@E.KTH.SE
May 3 13:55:56 May 3 23:55:54 krbtgt/SU.SE@E.KTH.SE
May 3 14:10:54 May 3 23:55:54 host/hummel.it.su.se@SU.SE
Info Catalog
(heimdal.info.gz) Encryption types and salting
(heimdal.info.gz) Setting up a realm
(heimdal.info.gz) Transit policy
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