cf771f223b
release, which fixes a DoS issue in libkrb5.
231 lines
8.1 KiB
Groff
231 lines
8.1 KiB
Groff
.\" Copyright (c) 2003 - 2004 Kungliga Tekniska Högskolan
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.\" (Royal Institute of Technology, Stockholm, Sweden).
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\"
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" 3. Neither the name of the Institute nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $Id$
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.\"
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.Dd August 24, 2006
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.Dt KDC 8
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.Os HEIMDAL
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.Sh NAME
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.Nm kdc
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.Nd Kerberos 5 server
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.Sh SYNOPSIS
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.Nm
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.Bk -words
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.Oo Fl c Ar file \*(Ba Xo
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.Fl Fl config-file= Ns Ar file
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.Xc
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.Oc
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.Op Fl p | Fl Fl no-require-preauth
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.Op Fl Fl max-request= Ns Ar size
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.Op Fl H | Fl Fl enable-http
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.Op Fl Fl no-524
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.Op Fl Fl kerberos4
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.Op Fl Fl kerberos4-cross-realm
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.Oo Fl r Ar string \*(Ba Xo
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.Fl Fl v4-realm= Ns Ar string
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.Xc
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.Oc
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.Oo Fl P Ar portspec \*(Ba Xo
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.Fl Fl ports= Ns Ar portspec
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.Xc
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.Oc
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.Op Fl Fl detach
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.Op Fl Fl disable-des
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.Op Fl Fl addresses= Ns Ar list of addresses
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.Ek
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.Sh DESCRIPTION
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.Nm
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serves requests for tickets.
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When it starts, it first checks the flags passed, any options that are
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not specified with a command line flag are taken from a config file,
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or from a default compiled-in value.
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.Pp
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Options supported:
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.Bl -tag -width Ds
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.It Fl c Ar file , Fl Fl config-file= Ns Ar file
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Specifies the location of the config file, the default is
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.Pa /var/heimdal/kdc.conf .
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This is the only value that can't be specified in the config file.
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.It Fl p , Fl Fl no-require-preauth
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Turn off the requirement for pre-autentication in the initial AS-REQ
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for all principals.
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The use of pre-authentication makes it more difficult to do offline
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password attacks.
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You might want to turn it off if you have clients
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that don't support pre-authentication.
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Since the version 4 protocol doesn't support any pre-authentication,
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serving version 4 clients is just about the same as not requiring
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pre-athentication.
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The default is to require pre-authentication.
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Adding the require-preauth per principal is a more flexible way of
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handling this.
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.It Fl Fl max-request= Ns Ar size
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Gives an upper limit on the size of the requests that the kdc is
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willing to handle.
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.It Fl H , Fl Fl enable-http
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Makes the kdc listen on port 80 and handle requests encapsulated in HTTP.
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.It Fl Fl no-524
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don't respond to 524 requests
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.It Fl Fl kerberos4
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respond to Kerberos 4 requests
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.It Fl Fl kerberos4-cross-realm
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respond to Kerberos 4 requests from foreign realms.
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This is a known security hole and should not be enabled unless you
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understand the consequences and are willing to live with them.
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.It Fl r Ar string , Fl Fl v4-realm= Ns Ar string
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What realm this server should act as when dealing with version 4
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requests.
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The database can contain any number of realms, but since the version 4
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protocol doesn't contain a realm for the server, it must be explicitly
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specified.
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The default is whatever is returned by
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.Fn krb_get_lrealm .
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This option is only available if the KDC has been compiled with version
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4 support.
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.It Fl P Ar portspec , Fl Fl ports= Ns Ar portspec
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Specifies the set of ports the KDC should listen on.
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It is given as a
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white-space separated list of services or port numbers.
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.It Fl Fl addresses= Ns Ar list of addresses
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The list of addresses to listen for requests on.
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By default, the kdc will listen on all the locally configured
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addresses.
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If only a subset is desired, or the automatic detection fails, this
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option might be used.
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.It Fl Fl detach
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detach from pty and run as a daemon.
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.It Fl Fl disable-des
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disable add des encryption types, makes the kdc not use them.
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.El
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.Pp
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All activities are logged to one or more destinations, see
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.Xr krb5.conf 5 ,
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and
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.Xr krb5_openlog 3 .
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The entity used for logging is
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.Nm kdc .
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.Sh CONFIGURATION FILE
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The configuration file has the same syntax as
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.Xr krb5.conf 5 ,
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but will be read before
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.Pa /etc/krb5.conf ,
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so it may override settings found there.
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Options specific to the KDC only are found in the
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.Dq [kdc]
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section.
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All the command-line options can preferably be added in the
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configuration file.
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The only difference is the pre-authentication flag, which has to be
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specified as:
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.Pp
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.Dl require-preauth = no
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.Pp
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(in fact you can specify the option as
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.Fl Fl require-preauth=no ) .
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.Pp
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And there are some configuration options which do not have
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command-line equivalents:
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.Bl -tag -width "xxx" -offset indent
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.It Li enable-digest = Va boolean
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turn on support for digest processing in the KDC.
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The default is FALSE.
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.It Li check-ticket-addresses = Va boolean
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Check the addresses in the ticket when processing TGS requests.
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The default is TRUE.
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.It Li allow-null-ticket-addresses = Va boolean
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Permit tickets with no addresses.
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This option is only relevant when check-ticket-addresses is TRUE.
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.It Li allow-anonymous = Va boolean
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Permit anonymous tickets with no addresses.
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.It Li max-kdc-datagram-reply-length = Va number
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Maximum packet size the UDP rely that the KDC will transmit, instead
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the KDC sends back a reply telling the client to use TCP instead.
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.It Li transited-policy = Li always-check \*(Ba \
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Li allow-per-principal | Li always-honour-request
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This controls how KDC requests with the
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.Li disable-transited-check
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flag are handled. It can be one of:
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.Bl -tag -width "xxx" -offset indent
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.It Li always-check
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Always check transited encoding, this is the default.
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.It Li allow-per-principal
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Currently this is identical to
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.Li always-check .
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In a future release, it will be possible to mark a principal as able
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to handle unchecked requests.
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.It Li always-honour-request
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Always do what the client asked.
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In a future release, it will be possible to force a check per
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principal.
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.El
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.It encode_as_rep_as_tgs_rep = Va boolean
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Encode AS-Rep as TGS-Rep to be bug-compatible with old DCE code.
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The Heimdal clients allow both.
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.It kdc_warn_pwexpire = Va time
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How long before password/principal expiration the KDC should start
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sending out warning messages.
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.El
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.Pp
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The configuration file is only read when the
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.Nm
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is started.
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If changes made to the configuration file are to take effect, the
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.Nm
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needs to be restarted.
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.Pp
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An example of a config file:
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.Bd -literal -offset indent
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[kdc]
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require-preauth = no
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v4-realm = FOO.SE
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.Ed
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.Sh BUGS
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If the machine running the KDC has new addresses added to it, the KDC
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will have to be restarted to listen to them.
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The reason it doesn't just listen to wildcarded (like INADDR_ANY)
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addresses, is that the replies has to come from the same address they
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were sent to, and most OS:es doesn't pass this information to the
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application.
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If your normal mode of operation require that you add and remove
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addresses, the best option is probably to listen to a wildcarded TCP
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socket, and make sure your clients use TCP to connect.
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For instance, this will listen to IPv4 TCP port 88 only:
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.Bd -literal -offset indent
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kdc --addresses=0.0.0.0 --ports="88/tcp"
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.Ed
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.Pp
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There should be a way to specify protocol, port, and address triplets,
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not just addresses and protocol, port tuples.
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.Sh SEE ALSO
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.Xr kinit 1 ,
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.Xr krb5.conf 5
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