auth_krb5(8)

1AUTH_KRB5(8)              InterNetNews Documentation              AUTH_KRB5(8)
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NAME

6       auth_krb5 - nnrpd Kerberos v5 authenticator
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SYNOPSIS

9       auth_krb5 [-i instance]
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DESCRIPTION

12       This program does authentication for nnrpd against a Kerberos v5 KDC.
13       This is NOT real Kerberos authentication using service tickets;
14       instead, a username and password is used to attempt to obtain a Ker‐
15       beros v5 TGT to confirm that they are valid.  As such, this authentica‐
16       tor assumes that nnrpd has been given the user's username and password,
17       and therefore is not as secure as real Kerberos authentication.  It
18       generally should only be used with NNTP over SSL to protect the pass‐
19       word from sniffing.
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OPTIONS

22       -i instance
23           If this option is given, instance will be used as the instance of
24           the principal received from nnrpd and authentication will be done
25           against that principal instead of the base principal.  In other
26           words, a principal like "user", when passed to auth_krb5 invoked
27           with "-i nntp", will be transformed into "user/nntp" before
28           attempting Kerberos authentication.
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30           Since giving one's password to nnrpd is not as secure as normal
31           Kerberos authentication, this option supports a configuration where
32           all users are given a separate instance just for news authentica‐
33           tion with its own password, so their regular account password isn't
34           exposed via NNTP.
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EXAMPLE

37       The following readers.conf(5) fragment tells nnrpd to authenticate
38       users by attempting to obtain Kerberos v5 TGTs for them, appending an
39       instance of "nntp" to usernames before doing so:
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41           auth kerberos {
42               auth: "auth_krb5 -i nntp"
43           }
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45           access kerberos {
46               users: "*/nntp"
47               newsgroups: example.*
48           }
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50       Access is granted to the example.* groups for all users who success‐
51       fully authenticate.
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BUGS

54       Currently, any username containing realm information (containing "@")
55       is rejected.  This is to prevent someone from passing in a username
56       corresponding to a principal in another realm that they have access to
57       and gaining access to the news server via it.  However, this is also
58       something that people may wish to do under some circumstances, so there
59       should be a better way of handling it (such as, perhaps, a list of
60       acceptable realms or a -r flag specifying the realm in which to attempt
61       authentication).
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63       It's not clear the right thing to do when the username passed in con‐
64       tains a "/" and -i was also given.  Right now, auth_krb5 will create a
65       malformed Kerberos principal with multiple instances and attempt to
66       authenticate against it, which will fail but perhaps not with the best
67       error message.
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HISTORY

70       Originally written by Christopher P. Lindsey.  This documentation was
71       written by Russ Allbery <rra@stanford.edu> based on Christopher's orig‐
72       inal README file.
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74       $Id: auth_krb5.8 5912 2002-12-03 05:31:11Z vinocur $
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