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several new kerberos related libraries and applications to FreeBSD:
o kgetcred(1) allows one to manually get a ticket for a particular service.
o kf(1) securily forwards ticket to another host through an authenticated
and encrypted stream.
o kcc(1) is an umbrella program around klist(1), kswitch(1), kgetcred(1)
and other user kerberos operations. klist and kswitch are just symlinks
to kcc(1) now.
o kswitch(1) allows you to easily switch between kerberos credentials if
you're running KCM.
o hxtool(1) is a certificate management tool to use with PKINIT.
o string2key(1) maps a password into key.
o kdigest(8) is a userland tool to access the KDC's digest interface.
o kimpersonate(8) creates a "fake" ticket for a service.
We also now install manpages for some lirbaries that were not installed
before, libheimntlm and libhx509.
- The new HEIMDAL version no longer supports Kerberos 4. All users are
recommended to switch to Kerberos 5.
- Weak ciphers are now disabled by default. To enable DES support (used
by telnet(8)), use "allow_weak_crypto" option in krb5.conf.
- libtelnet, pam_ksu and pam_krb5 are now compiled with error on warnings
disabled due to the function they use (krb5_get_err_text(3)) being
deprecated. I plan to work on this next.
- Heimdal's KDC now require sqlite to operate. We use the bundled version
and install it as libheimsqlite. If some other FreeBSD components will
require it in the future we can rename it to libbsdsqlite and use for these
components as well.
- This is not a latest Heimdal version, the new one was released while I was
working on the update. I will update it to 1.5.2 soon, as it fixes some
important bugs and security issues.
59 lines
2.6 KiB
Plaintext
59 lines
2.6 KiB
Plaintext
@c $Id$
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@node Things in search for a better place, Kerberos 4 issues, Applications, Top
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@chapter Things in search for a better place
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@section Making things work on Ciscos
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Modern versions of Cisco IOS has some support for authenticating via
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Kerberos 5. This can be used both by having the router get a ticket when
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you login (boring), and by using Kerberos authenticated telnet to access
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your router (less boring). The following has been tested on IOS
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11.2(12), things might be different with other versions. Old versions
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are known to have bugs.
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To make this work, you will first have to configure your router to use
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Kerberos (this is explained in the documentation). A sample
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configuration looks like the following:
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@example
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aaa new-model
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aaa authentication login default krb5-telnet krb5 enable
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aaa authorization exec krb5-instance
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kerberos local-realm FOO.SE
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kerberos srvtab entry host/router.foo.se 0 891725446 4 1 8 012345678901234567
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kerberos server FOO.SE 10.0.0.1
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kerberos instance map admin 15
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@end example
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This tells you (among other things) that when logging in, the router
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should try to authenticate with kerberised telnet, and if that fails try
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to verify a plain text password via a Kerberos ticket exchange (as
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opposed to a local database, RADIUS or something similar), and if that
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fails try the local enable password. If you're not careful when you
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specify the `login default' authentication mechanism, you might not be
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able to login at all. The `instance map' and `authorization exec' lines
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says that people with `admin' instances should be given `enabled' shells
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when logging in.
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The numbers after the principal on the `srvtab' line are principal type,
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time stamp (in seconds since 1970), key version number (4), keytype (1 ==
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des), key length (always 8 with des), and then the key.
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To make the Heimdal KDC produce tickets that the Cisco can decode you
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might have to turn on the @samp{encode_as_rep_as_tgs_rep} flag in the
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KDC. You will also have to specify that the router can't handle anything
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but @samp{des-cbc-crc}. This can be done with the @samp{del_enctype}
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command of @samp{kadmin}.
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This all fine and so, but unless you have an IOS version with encryption
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(available only in the U.S) it doesn't really solve any problems. Sure
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you don't have to send your password over the wire, but since the telnet
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connection isn't protected it's still possible for someone to steal your
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session. This won't be fixed until someone adds integrity to the telnet
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protocol.
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A working solution would be to hook up a machine with a real operating
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system to the console of the Cisco and then use it as a backwards
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terminal server.
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