path: root/doc/install.texinfo

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\input texinfo @c -*-texinfo-*-
@c %**start of header
@c guide
@setfilename krb5-install.info
@settitle Kerberos V5 Installation Guide
@setchapternewpage odd                  @c chapter begins on next odd page
@c @setchapternewpage on                   @c chapter begins on next page
@c @smallbook                              @c Format for 7" X 9.25" paper
@documentencoding UTF-8
@c %**end of header
@copying
Copyright @copyright{} 1985-2010 by the Massachusetts Institute of Technology.
@end copying

@paragraphindent 0
@iftex
@parskip 6pt plus 6pt
@end iftex

@dircategory Kerberos
@direntry
* krb5-install: (krb5-install).         Kerberos V5 Installation Guide
@end direntry

@include definitions.texinfo
@set EDITION 1.1

@finalout                               @c don't print black warning boxes

@titlepage
@title @value{PRODUCT} Installation Guide
@subtitle Release:  @value{RELEASE}
@subtitle Document Edition:  @value{EDITION}
@subtitle Last updated:  @value{UPDATED}
@author @value{COMPANY}

@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@node Top, Introduction, (dir), (dir)
@comment  node-name,  next,  previous,  up

@ifinfo
This file documents how to install the @value{RELEASE} release of
@value{PRODUCT}.

@insertcopying
@end ifinfo

@c The master menu is updated using emacs19's M-x texinfo-all-menus-update
@c function.  Don't forget to run M-x texinfo-every-node-update after
@c you add a new section or subsection, or after you've rearranged the
@c order of sections or subsections.  Also, don't forget to add an @node
@c comand before each @section or @subsection!  All you need to enter
@c is:
@c
@c @node New Section Name

@c @section New Section Name
@c
@c M-x texinfo-every-node-update will take care of calculating the
@c node's forward and back pointers.
@c
@c ---------------------------------------------------------------------

@menu
* Introduction::                
* Realm Configuration Decisions::  
* Building Kerberos V5::        
* Installing Kerberos V5::      
* Upgrading Existing Kerberos V5 Installations::  
* Bug Reports for Kerberos V5::  
* Copyright::                   
@end menu

@node Introduction, Realm Configuration Decisions, Top, Top
@chapter Introduction

@menu
* What is Kerberos and How Does it Work?::  
* Why Should I use Kerberos?::  
* Please Read the Documentation::  
* Overview of This Guide::      
@end menu

@node What is Kerberos and How Does it Work?, Why Should I use Kerberos?, Introduction, Introduction
@section What is Kerberos and How Does it Work?

@value{PRODUCT} is based on the Kerberos authentication system developed
at MIT.  Under Kerberos, a client (generally either a user or a service)
sends a request for a ticket to the Key Distribution Center (KDC).  The
KDC creates a @dfn{ticket-granting ticket} (TGT) for the client,
encrypts it using the client's password as the key, and sends the
encrypted TGT back to the client.  The client then attempts to decrypt
the TGT, using its password.  If the client successfully decrypts the
TGT (@i{i.e.}, if the client gave the correct password), it keeps the
decrypted TGT, which indicates proof of the client's identity.

The TGT, which expires at a specified time, permits the client to obtain
additional tickets, which give permission for specific services.  The
requesting and granting of these additional tickets is user-transparent.

@node Why Should I use Kerberos?, Please Read the Documentation, What is Kerberos and How Does it Work?, Introduction
@section Why Should I use Kerberos?

Since Kerberos negotiates authenticated, and optionally encrypted,
communications between two points anywhere on the Internet, it provides
a layer of security that is not dependent on which side of a firewall
either client is on.  Since studies have shown that half of the computer
security breaches in industry happen from @i{inside} firewalls,
@value{PRODUCT} from @value{COMPANY} will play a vital role in the
security of your network.

@node Please Read the Documentation, Overview of This Guide, Why Should I use Kerberos?, Introduction
@section Please Read the Documentation

As with any software package that uses a centrallized database, the
installation procedure is somewhat involved, and requires forethought
and planning.  @value{COMPANY} has attempted to make this
@value{PRODUCT} Installation Guide as concise as possible, rather than
making it an exhaustive description of the details of Kerberos.
@ifset CYGNUS
Consequently, everything in this guide appears because @value{COMPANY}
believes that it is important.  Please read and follow these
instructions carefully, and if there is anything you do not understand
or are not sure of, please don't hesitate to call us.
@end ifset
@ifset MIT
Consequently, everything in this guide appears because @value{COMPANY}
believes that it is important.  Please read and follow these
instructions carefully.
@end ifset

@include document-list.texinfo

@node Overview of This Guide,  , Please Read the Documentation, Introduction
@section Overview of This Guide

@noindent
The next chapter describes the decisions you need to make before
installing @value{PRODUCT}.

@noindent
Chapter three provided instructions for building the Kerberos sources.

@noindent
Chapter four describes installation procedures for each class of
Kerberos machines:

@enumerate
@item
Key Distribution Centers (KDCs).

@enumerate A
@item
The Master KDC.

@item
Slave KDCs.
@end enumerate

@item
UNIX client machines

@item
UNIX application server machines
@end enumerate

@noindent
Note that a machine can be both a client machine and an application
server.

@noindent
Chapter five describes procedure for updating previous installations of
@value{PRODUCT}.

@noindent
Chapter six describes our problem reporting system.

@node Realm Configuration Decisions, Building Kerberos V5, Introduction, Top
@chapter Realm Configuration Decisions

Before installing @value{PRODUCT}, it is necessary to consider the
following issues:

@itemize @bullet
@item
The name of your Kerberos realm (or the name of each realm, if you need
more than one).

@item
How you will map your hostnames onto Kerberos realms.

@item
Which ports your KDC and and kadmin (database access) services will use.

@item
How many slave KDCs you need and where they should be located.

@item
The hostnames of your master and slave KDCs.

@item
How frequently you will propagate the database from the master KDC to
the slave KDCs.
@end itemize

@menu
* Kerberos Realms::             
* Mapping Hostnames onto Kerberos Realms::  
* Ports for the KDC and Admin Services::  
* Slave KDCs::                  
* Hostnames for the Master and Slave KDCs::  
* Database Propagation::        
@end menu

@node Kerberos Realms, Mapping Hostnames onto Kerberos Realms, Realm Configuration Decisions, Realm Configuration Decisions
@section Kerberos Realms

Although your Kerberos realm can be any ASCII string, convention is to
make it the same as your domain name, in upper-case letters.  For
example, hosts in the domain @value{SECONDDOMAIN} would be in the
Kerberos realm @value{SECONDREALM}.

If you need multiple Kerberos realms, @value{COMPANY} recommends that
you use descriptive names which end with your domain name, such as
BOSTON.@value{SECONDREALM} and HOUSTON.@value{SECONDREALM}.

@node Mapping Hostnames onto Kerberos Realms, Ports for the KDC and Admin Services, Kerberos Realms, Realm Configuration Decisions
@section Mapping Hostnames onto Kerberos Realms

@include dnstxt.texinfo

@node Ports for the KDC and Admin Services, Slave KDCs, Mapping Hostnames onto Kerberos Realms, Realm Configuration Decisions
@section Ports for the KDC and Admin Services

The default ports used by Kerberos are port @value{DefaultPort} for the
KDC@footnote{Kerberos V4 used port @value{DefaultSecondPort}.  If
necessary, you can run on both ports for backward compatibility.}  and
port @value{DefaultKadmindPort} for the admin server.  You can, however,
choose to run on other ports, as long as they are specified in each
host's @code{/etc/services} and @code{krb5.conf} files, and the
@code{kdc.conf} file on each KDC.  For a more thorough treatment of
port numbers used by the @value{PRODUCT} programs, refer to the
``Configuring Your Firewall to Work With @value{PRODUCT}'' section of
the @cite{@value{PRODUCT} System Administrator's Guide}.

@node Slave KDCs, Hostnames for the Master and Slave KDCs, Ports for the KDC and Admin Services, Realm Configuration Decisions
@section Slave KDCs

Slave KDCs provide an additional source of Kerberos ticket-granting
services in the event of inaccessibility of the master KDC.  The number
of slave KDCs you need and the decision of where to place them, both
physically and logically, depends on the specifics of your network.

All of the Kerberos authentication on your network requires that each
client be able to contact a KDC.  Therefore, you need to anticipate any
likely reason a KDC might be unavailable and have a slave KDC to take up
the slack.

Some considerations include:

@itemize @bullet
@item
Have at least one slave KDC as a backup, for when the master KDC is
down, is being upgraded, or is otherwise unavailable.

@item
If your network is split such that a network outage is likely to cause a
network partition (some segment or segments of the network to become cut
off or isolated from other segments), have a slave KDC accessible to
each segment.

@item
If possible, have at least one slave KDC in a different building from
the master, in case of power outages, fires, or other localized
disasters.
@end itemize



@node Hostnames for the Master and Slave KDCs, Database Propagation, Slave KDCs, Realm Configuration Decisions
@section Hostnames for the Master and Slave KDCs

@include dnssrv.texinfo

@node Database Propagation,  , Hostnames for the Master and Slave KDCs, Realm Configuration Decisions
@section Database Propagation

The Kerberos database resides on the master KDC, and must be propagated
regularly (usually by a cron job) to the slave KDCs.  In deciding how
frequently the propagation should happen, you will need to balance the
amount of time the propagation takes against the maximum reasonable
amount of time a user should have to wait for a password change to take
effect.

If the propagation time is longer than this maximum reasonable time
(@i{e.g.,} you have a particularly large database, you have a lot of
slaves, or you experience frequent network delays), you may wish to
cut down on your propagation delay by performing the propagation in
parallel.  To do this, have the master KDC propagate the database to one
set of slaves, and then have each of these slaves propagate the database
to additional slaves.

@node Building Kerberos V5, Installing Kerberos V5, Realm Configuration Decisions, Top
@chapter Building @value{PRODUCT}

@include build.texinfo

@node Installing Kerberos V5, Upgrading Existing Kerberos V5 Installations, Building Kerberos V5, Top
@chapter Installing @value{PRODUCT}

The sections of this chapter describe procedures for installing
@value{PRODUCT} on:

@enumerate
@item
The KDCs

@item
UNIX client machines

@item
UNIX Application Servers
@end enumerate

@menu
* Installing KDCs::             
* Installing and Configuring UNIX Client Machines::  
* UNIX Application Servers::    
@end menu

@node Installing KDCs, Installing and Configuring UNIX Client Machines, Installing Kerberos V5, Installing Kerberos V5
@section Installing KDCs

The Key Distribution Centers (KDCs) issue Kerberos tickets.  Each KDC
contains a copy of the Kerberos database.  The master KDC contains the
master copy of the database, which it propagates to the slave KDCs at
regular intervals.  All database changes (such as password changes) are
made on the master KDC.

Slave KDCs provide Kerberos ticket-granting services, but not database
administration.  This allows clients to continue to obtain tickets when
the master KDC is unavailable.

@value{COMPANY} recommends that you install all of your KDCs to be able
to function as either the master or one of the slaves.  This will enable
you to easily switch your master KDC with one of the slaves if
necessary.  (@xref{Switching Master and Slave KDCs}.)  This installation
procedure is based on that recommendation.

@menu
* Install the Master KDC::      
* Install the Slave KDCs::      
* Back on the Master KDC::      
* Finish Installing the Slave KDCs::  
* Add Kerberos Principals to the Database::  
* Limit Access to the KDCs::    
* Switching Master and Slave KDCs::  
* Incremental Database Propagation::  
@end menu

@node Install the Master KDC, Install the Slave KDCs, Installing KDCs, Installing KDCs
@subsection Install the Master KDC

This installation procedure will require you to go back and forth a
couple of times between the master KDC and each of the slave KDCs.  The
first few steps must be done on the master KDC.

@menu
* Edit the Configuration Files::  
* krb5.conf::                   
* kdc.conf::                    
* Create the Database::         
* Add Administrators to the Acl File::  
* Add Administrators to the Kerberos Database::  
* Create a kadmind Keytab (optional)::  
* Start the Kerberos Daemons::  
@end menu

@node Edit the Configuration Files, krb5.conf, Install the Master KDC, Install the Master KDC
@subsubsection Edit the Configuration Files

Modify the configuration files, @code{/etc/krb5.conf} and
@code{@value{ROOTDIR}/var/krb5kdc/kdc.conf} to reflect the correct
information (such as the hostnames and realm name) for your realm.
@value{COMPANY} recommends that you keep @code{krb5.conf} in @code{/etc}.

Most of the tags in the configuration have default values that will
work well for most sites.  There are some tags in the @code{krb5.conf}
file whose values must be specified, and this section will explain
those as well as give an overview of all of the sections in both
configuration files.  For more information on changing defaults with
the configuration files, see the @value{PRODUCT} System Administrator's
Guide sections on configuration files. 

@node krb5.conf, kdc.conf, Edit the Configuration Files, Install the Master KDC
@subsubsection krb5.conf

@include krb5conf.texinfo

If you are not using DNS TXT records, you must specify the
@code{default_realm} in the @code{libdefaults} section.  If you are not
using DNS SRV records, you must include the @code{kdc} tag for each
realm in the @code{realms} section.  To communicate with the kadmin
server in each realm, the @code{admin_server} tag must be set in the
@code{realms} section.  If your domain name and realm name are not the
same, you must provide a translation in @code{domain_realm}.  It is
also higly recommeneded that you create a @code{[logging]} stanza if
the computer will be functioning as a KDC so that the KDC and kadmind
will generate logging output.

An example @code{krb5.conf} file:

@smallexample
@group
[libdefaults]
    default_realm = @value{PRIMARYREALM}

[realms]
    @value{PRIMARYREALM} = @{
    	kdc = @value{KDCSERVER}.@value{PRIMARYDOMAIN}
    	kdc = @value{KDCSLAVE1}.@value{PRIMARYDOMAIN}
    	kdc = @value{KDCSLAVE2}.@value{PRIMARYDOMAIN}
    	admin_server = @value{KDCSERVER}.@value{PRIMARYDOMAIN}
    @{

[logging]
    kdc = FILE:/var/log/krb5kdc.log
    admin_server = FILE:/var/log/kadmin.log
    default = FILE:/var/log/krb5lib.log
@end group
@end smallexample

@node kdc.conf, Create the Database, krb5.conf, Install the Master KDC
@subsubsection kdc.conf

@include kdcconf.texinfo

@node Create the Database, Add Administrators to the Acl File, kdc.conf, Install the Master KDC
@subsubsection Create the Database

You will use the @code{kdb5_util} command @emph{on the Master KDC} to
create the Kerberos database and the optional stash file.  The
@dfn{stash file} is a local copy of the master key that resides in
encrypted form on the KDC's local disk.  The stash file is used to
authenticate the KDC to itself automatically before starting the
@code{kadmind} and @code{krb5kdc} daemons (@i{e.g.,} as part of the
machine's boot sequence).  The stash file, like the keytab file
(see @xref{The Keytab File}, for more information) is a potential
point-of-entry for a break-in,
and if compromised, would allow unrestricted access to the Kerberos
database.  If you choose to install a stash file, it should be readable
only by root, and should exist only on the KDC's local disk.  The file
should not be part of any backup of the machine, unless access to the
backup data is secured as tightly as access to the master password
itself.

If you choose not to install a stash file, the KDC will prompt you for
the master key each time it starts up.  This means that the KDC will
not be able to start automatically, such as after a system reboot.

Note that @code{kdb5_util} will prompt you for the master key for the
Kerberos database.  This key can be any string.  A good key is one you
can remember, but that no one else can guess.  Examples of bad keys are
words that can be found in a dictionary, any common or popular name,
especially a famous person (or cartoon character), your username in any
form (@i{e.g.}, forward, backward, repeated twice, @i{etc.}), and any of
the sample keys that appear in this manual.  One example of a key which
might be good if it did not appear in this manual is ``MITiys4K5!'',
which represents the sentence ``MIT is your source for Kerberos 5!''
(It's the first letter of each word, substituting the numeral ``4'' for
the word ``for'', and includes the punctuation mark at the end.)

The following is an example of how to create a Kerberos database and
stash file on the master KDC, using the @code{kdb5_util} command.  (The
line that begins with @result{} is a continuation of the previous line.)
Replace @i{@value{PRIMARYREALM}} with the name of your Kerberos realm.

@smallexample
@group
@b{shell%} @value{ROOTDIR}/sbin/kdb5_util create -r @value{PRIMARYREALM} -s
@b{Initializing database '@value{ROOTDIR}/var/krb5kdc/principal' for
@result{} realm '@value{PRIMARYREALM}',
master key name 'K/M@@@value{PRIMARYREALM}'
You will be prompted for the database Master Password.
It is important that you NOT FORGET this password.}
@iftex
@b{Enter KDC database master key:}  @i{@doubleleftarrow{} Type the master password.}
@b{Re-enter KDC database master key to verify:}  @i{@doubleleftarrow{} Type it again.}
@end iftex
@ifinfo
@b{Enter KDC database master key:}  @i{<= Type the master password.}
@b{Re-enter KDC database master key to verify:}  @i{<= Type it again.}
@end ifinfo
@ifhtml
@b{Enter KDC database master key:}  @i{<= Type the master password.}
@b{Re-enter KDC database master key to verify:}  @i{<= Type it again.}
@end ifhtml
@b{shell%}
@end group
@end smallexample

This will create five files in the directory specified in your
@code{kdc.conf} file:  two Kerberos database files, @code{principal.db},
and @code{principal.ok}; the Kerberos administrative database file,
@code{principal.kadm5}; the administrative database lock file,
@code{principal.kadm5.lock}; and the stash file, @code{.k5stash}.  (The
default directory is @code{@value{ROOTDIR}/var/krb5kdc}.)  If you do not
want a stash file, run the above command without the @code{-s} option.

@node Add Administrators to the Acl File, Add Administrators to the Kerberos Database, Create the Database, Install the Master KDC
@subsubsection Add Administrators to the Acl File

Next, you need create an Access Control List (acl) file, and put the
Kerberos principal of at least one of the administrators into it.  This
file is used by the @code{kadmind} daemon to control which principals
may view and make privileged modifications to the Kerberos database
files.  The filename should match the value you have set for
``acl_file'' in your @code{kdc.conf} file.  The default file name is
@samp{@value{DefaultAclFile}}.

@include kadm5acl.texinfo

@node Add Administrators to the Kerberos Database, Create a kadmind Keytab (optional), Add Administrators to the Acl File, Install the Master KDC
@subsubsection Add Administrators to the Kerberos Database

Next you need to add administrative principals to the Kerberos database.
(You must add at least one now.)  To do this, use @code{kadmin.local}
@emph{on the master KDC}.  The administrative principals you create
should be the ones you added to the ACL file.  (See @xref{Add
Administrators to the Acl File}.)  In the following example, the
administration principal @code{admin/admin} is created:

@smallexample
@group
@b{shell%} @value{ROOTDIR}/sbin/kadmin.local
@b{kadmin.local:} addprinc admin/admin@@@value{PRIMARYREALM}
@b{NOTICE: no policy specified for "admin/admin@@@value{PRIMARYREALM}";
assigning "default".}
@iftex
@b{Enter password for principal admin/admin@@@value{PRIMARYREALM}:}  @i{@doubleleftarrow{} Enter a password.}
Re-enter password for principal admin/admin@@@value{PRIMARYREALM}:  @i{@doubleleftarrow{} Type it again.}
@end iftex
@ifinfo
@b{Enter password for principal admin/admin@@@value{PRIMARYREALM}:}  @i{<= Enter a password.}
Re-enter password for principal admin/admin@@@value{PRIMARYREALM}:  @i{<= Type it again.}
@end ifinfo
@ifhtml
@b{Enter password for principal admin/admin@@@value{PRIMARYREALM}:}  @i{<= Enter a password.}
Re-enter password for principal admin/admin@@@value{PRIMARYREALM}:  @i{<= Type it again.}
@end ifhtml
@b{Principal "admin/admin@@@value{PRIMARYREALM}" created.
kadmin.local:}
@end group
@end smallexample



@node Create a kadmind Keytab (optional), Start the Kerberos Daemons, Add Administrators to the Kerberos Database, Install the Master KDC
@subsubsection Create a kadmind Keytab (optional)

The kadmind keytab is the key that the legacy admininstration daemons
@code{kadmind4} and @code{v5passwdd} will use to decrypt
administrators' or clients' Kerberos tickets to determine whether or
not they should have access to the database.  You need to create the
kadmin keytab with entries for the principals @code{kadmin/admin} and
@code{kadmin/changepw}.  (These principals are placed in the Kerberos
database automatically when you create it.)  To create the kadmin
keytab, run @code{kadmin.local} and use the @code{ktadd} command, as
in the following example.  (The line beginning with @result{} is a
continuation of the previous line.):

@smallexample
@group
@b{shell%} @value{ROOTDIR}/sbin/kadmin.local
@b{kadmin.local:} ktadd -k @value{ROOTDIR}/var/krb5kdc/kadm5.keytab
@result{} kadmin/admin kadmin/changepw 
@b{ Entry for principal kadmin/admin with kvno 5, encryption
	type Triple DES cbc mode with HMAC/sha1 added to keytab
	WRFILE:/usr/local/var/krb5kdc/kadm5.keytab.
Entry for principal kadmin/admin with kvno 5, encryption type DES cbc mode
	with CRC-32 added to keytab
	WRFILE:/usr/local/var/krb5kdc/kadm5.keytab.
Entry for principal kadmin/changepw with kvno 5, encryption
	type Triple DES cbc mode with HMAC/sha1 added to keytab
	WRFILE:/usr/local/var/krb5kdc/kadm5.keytab.
Entry for principal kadmin/changepw with kvno 5,
	encryption type DES cbc mode with CRC-32 added to keytab
	WRFILE:/usr/local/var/krb5kdc/kadm5.keytab.
kadmin.local:} quit
@b{shell%}
@end group
@end smallexample

@noindent
As specified in the @samp{-k} argument, @code{ktadd} will save the
extracted keytab as @* @code{@value{ROOTDIR}/var/krb5kdc/kadm5.keytab}.
The filename you use must be the one specified in your @code{kdc.conf}
file.

@need 2000
@node Start the Kerberos Daemons,  , Create a kadmind Keytab (optional), Install the Master KDC
@subsubsection Start the Kerberos Daemons on the Master KDC

At this point, you are ready to start the Kerberos daemons on the Master
KDC.  To do so, type:

@smallexample
@b{shell%} @value{ROOTDIR}/sbin/krb5kdc
@b{shell%} @value{ROOTDIR}/sbin/kadmind
@end smallexample

@noindent
Each daemon will fork and run in the background.  Assuming you want
these daemons to start up automatically at boot time, you can add them
to the KDC's @code{/etc/rc} or @code{/etc/inittab} file.  You need to
have a stash file in order to do this.

You can verify that they started properly by checking for their startup
messages in the logging locations you defined in @code{/etc/krb5.conf}.
(@xref{Edit the Configuration Files}.)  For example:

@smallexample
@b{shell%} tail /var/log/krb5kdc.log
Dec 02 12:35:47 beeblebrox krb5kdc[3187](info): commencing operation
@b{shell%} tail /var/log/kadmin.log
Dec 02 12:35:52 beeblebrox kadmind[3189](info): starting
@end smallexample

Any errors the daemons encounter while starting will also be listed in
the logging output.


@node Install the Slave KDCs, Back on the Master KDC, Install the Master KDC, Installing KDCs
@subsection Install the Slave KDCs

You are now ready to start configuring the slave KDCs.  Assuming you are
setting the KDCs up so that you can easily switch the master KDC with
one of the slaves, you should perform each of these steps on the master
KDC as well as the slave KDCs, unless these instructions specify
otherwise.


@menu
* Create Host Keys for the Slave KDCs::  
* Extract Host Keytabs for the KDCs::  
* Set Up the Slave KDCs for Database Propagation::  
@end menu

@node Create Host Keys for the Slave KDCs, Extract Host Keytabs for the KDCs, Install the Slave KDCs, Install the Slave KDCs
@subsubsection Create Host Keys for the Slave KDCs

Each KDC needs a host principal in the Kerberos database.  You can enter
these from any host, once the @code{kadmind} daemon is running.  For
example, if your master KDC were called
@value{KDCSERVER}.@value{PRIMARYDOMAIN}, and you had two KDC slaves
named @value{KDCSLAVE1}.@value{PRIMARYDOMAIN} and
@value{KDCSLAVE2}.@value{PRIMARYDOMAIN}, you would type the following:

@smallexample
@group
@b{shell%} @value{ROOTDIR}/sbin/kadmin
@b{kadmin:} addprinc -randkey host/@value{KDCSERVER}.@value{PRIMARYDOMAIN}
@b{NOTICE: no policy specified for "host/@value{KDCSERVER}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}";
assigning "default"
Principal "host/@value{KDCSERVER}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}" created.
kadmin:} addprinc -randkey host/@value{KDCSLAVE1}.@value{PRIMARYDOMAIN}
@b{NOTICE: no policy specified for "host/@value{KDCSLAVE1}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}";
assigning "default"
Principal "host/@value{KDCSLAVE1}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}" created.}
@b{kadmin:} addprinc -randkey host/@value{KDCSLAVE2}.@value{PRIMARYDOMAIN}
@b{NOTICE: no policy specified for "host/@value{KDCSLAVE2}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}";
assigning "default"
Principal "host/@value{KDCSLAVE2}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}" created.
kadmin:}
@end group
@end smallexample

@noindent
It is not actually necessary to have the master KDC server in the
Kerberos database, but it can be handy if:

@itemize @bullet
@item
anyone will be logging into the machine as something other than root

@item
you want to be able to swap the master KDC with one of the slaves if
necessary.
@end itemize

@node Extract Host Keytabs for the KDCs, Set Up the Slave KDCs for Database Propagation, Create Host Keys for the Slave KDCs, Install the Slave KDCs
@subsubsection Extract Host Keytabs for the KDCs

Each KDC (including the master) needs a keytab to decrypt tickets.
Ideally, you should extract each keytab locally on its own KDC.  If this
is not feasible, you should use an encrypted session to send them across
the network.  To extract a keytab on a KDC called
@value{KDCSERVER}.@value{PRIMARYDOMAIN}, you would execute the following
command:

@smallexample
@group
@b{kadmin:} ktadd host/@value{KDCSERVER}.@value{PRIMARYDOMAIN}
@b{kadmin: Entry for principal host/@value{KDCSERVER}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM} with
     kvno 1, encryption type DES-CBC-CRC added to keytab
     WRFILE:/etc/krb5.keytab.
kadmin:}
@end group
@end smallexample

@noindent
Note that the principal must exist in the Kerberos database in order to
extract the keytab.

@node Set Up the Slave KDCs for Database Propagation,  , Extract Host Keytabs for the KDCs, Install the Slave KDCs
@subsubsection Set Up the Slave KDCs for Database Propagation

The database is propagated from the master KDC to the slave KDCs via the
@code{kpropd} daemon.  To set up propagation, create a file on each KDC,
named @code{@value{ROOTDIR}/var/krb5kdc/kpropd.acl}, containing the
principals for each of the KDCs.
@need 1200
For example, if the master KDC were
@code{@value{KDCSERVER}.@value{PRIMARYDOMAIN}}, the slave KDCs were
@code{@value{KDCSLAVE1}.@value{PRIMARYDOMAIN}} and
@code{@value{KDCSLAVE2}.@value{PRIMARYDOMAIN}}, and the realm were
@code{@value{PRIMARYREALM}}, then the file's contents would be:

@smallexample
@group
host/@value{KDCSERVER}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}
host/@value{KDCSLAVE1}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}
host/@value{KDCSLAVE2}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}
@end group
@end smallexample
 
@need 1000
Then, add the following line to @code{/etc/inetd.conf} file on each KDC:

@smallexample
@group
krb5_prop stream tcp nowait root @value{ROOTDIR}/sbin/kpropd kpropd
@end group
@end smallexample

@noindent
You also need to add the following lines to @code{/etc/services} on each
KDC:

@smallexample
@group
kerberos        88/udp      kdc       # Kerberos authentication (udp)
kerberos        88/tcp      kdc       # Kerberos authentication (tcp)
krb5_prop       754/tcp               # Kerberos slave propagation
kerberos-adm    749/tcp               # Kerberos 5 admin/changepw (tcp)
kerberos-adm    749/udp               # Kerberos 5 admin/changepw (udp)
@end group
@end smallexample

@node Back on the Master KDC, Finish Installing the Slave KDCs, Install the Slave KDCs, Installing KDCs
@subsection Back on the Master KDC

Now that the slave KDCs are able to accept database propagation, you'll
need to propagate the database to each of them.

@menu
* Propagate the Database to Each Slave KDC::  
@end menu

@node Propagate the Database to Each Slave KDC,  , Back on the Master KDC, Back on the Master KDC
@subsubsection Propagate the Database to Each Slave KDC

First, create a dump of the database on the master KDC, as follows:

@smallexample
@group
@b{shell%} @value{ROOTDIR}/sbin/kdb5_util dump @value{ROOTDIR}/var/krb5kdc/slave_datatrans
@b{shell%}
@end group
@end smallexample

Next, you need to manually propagate the database to each slave KDC, as
in the following example.  (The lines beginning with @result{} are
continuations of the previous line.):

@smallexample
@group
@value{ROOTDIR}/sbin/kprop -f @value{ROOTDIR}/var/krb5kdc/slave_datatrans
@result{} @value{KDCSLAVE1}.@value{PRIMARYDOMAIN}
@value{ROOTDIR}/sbin/kprop -f @value{ROOTDIR}/var/krb5kdc/slave_datatrans
@result{} @value{KDCSLAVE2}.@value{PRIMARYDOMAIN}
@end group
@end smallexample

You will need a script to dump and propagate the database.  The
following is an example of a bourne shell script that will do this.
(Note that the line that begins with @result{} is a continuation of the
previous line.  Remember that you need to replace @value{ROOTDIR} with
the name of the directory in which you installed @value{PRODUCT}.)

@smallexample
@group
#!/bin/sh

kdclist = "@value{KDCSLAVE1}.@value{PRIMARYDOMAIN} @value{KDCSLAVE2}.@value{PRIMARYDOMAIN}"

@value{ROOTDIR}/sbin/kdb5_util "dump
@result{} @value{ROOTDIR}/var/krb5kdc/slave_datatrans"

for kdc in $kdclist
do
@value{ROOTDIR}/sbin/kprop -f @value{ROOTDIR}/var/krb5kdc/slave_datatrans $kdc
done
@end group
@end smallexample

@noindent
You will need to set up a cron job to run this script at the intervals
you decided on earlier (@xref{Database Propagation}.)

@node Finish Installing the Slave KDCs, Add Kerberos Principals to the Database, Back on the Master KDC, Installing KDCs
@subsection Finish Installing the Slave KDCs

Now that the slave KDCs have copies of the Kerberos database, you can
create stash files for them and start the @code{krb5kdc} daemon.

@menu
* Create Stash Files on the Slave KDCs::  
* Start the krb5kdc Daemon on Each KDC::  
@end menu

@node Create Stash Files on the Slave KDCs, Start the krb5kdc Daemon on Each KDC, Finish Installing the Slave KDCs, Finish Installing the Slave KDCs
@subsubsection Create Stash Files on the Slave KDCs

Create stash files, by issuing the following commands on each slave KDC:

@smallexample
@group
@b{shell%} kdb5_util stash
@b{kdb5_util: Cannot find/read stored master key while reading master key
kdb5_util: Warning: proceeding without master key}
@iftex
@b{Enter KDC database master key:}  @i{@doubleleftarrow{} Enter the database master key.}
@end iftex
@ifinfo
@b{Enter KDC database master key:}  @i{<= Enter the database master key.}
@end ifinfo
@ifhtml
@b{Enter KDC database master key:}  @i{<= Enter the database master key.}
@end ifhtml
@b{shell%}
@end group
@end smallexample

As mentioned above, the stash file is necessary for your KDCs to be able
authenticate to themselves, such as when they reboot.  You could run
your KDCs without stash files, but you would then need to type in the
Kerberos database master key by hand every time you start a KDC daemon.

@node Start the krb5kdc Daemon on Each KDC,  , Create Stash Files on the Slave KDCs, Finish Installing the Slave KDCs
@subsubsection Start the krb5kdc Daemon on Each KDC

The final step in configuing your slave KDCs is to run the KDC daemon:

@smallexample
@group
@b{shell%} @value{ROOTDIR}/sbin/krb5kdc
@end group
@end smallexample

As with the master KDC, you will probably want to add this command to
the KDCs' @code{/etc/rc} or @code{/etc/inittab} files, so they will
start the krb5kdc daemon automatically at boot time.

@node Add Kerberos Principals to the Database, Limit Access to the KDCs, Finish Installing the Slave KDCs, Installing KDCs
@subsection Add Kerberos Principals to the Database

@need 1800
Once your KDCs are set up and running, you are ready to use
@code{kadmin} to load principals for your users, hosts, and other
services into the Kerberos database.  This procedure is described fully in the
``Adding or Modifying Principals'' section of the @value{PRODUCT} System
Administrator's Guide.  (@xref{Create Host Keys for the Slave KDCs}, for a
brief description.)  The keytab is generated by running @code{kadmin}
and issuing the @code{ktadd} command.

@node Limit Access to the KDCs, Switching Master and Slave KDCs, Add Kerberos Principals to the Database, Installing KDCs
@subsection Limit Access to the KDCs

To limit the possibility that your Kerberos database could be
compromised, @value{COMPANY} recommends that each KDC be a dedicated
host, with limited access.  If your KDC is also a file server, FTP
server, Web server, or even just a client machine, someone who obtained
root access through a security hole in any of those areas could gain
access to the Kerberos database.

@node Switching Master and Slave KDCs, Incremental Database Propagation, Limit Access to the KDCs, Installing KDCs
@subsection Switching Master and Slave KDCs

You may occasionally want to use one of your slave KDCs as the master.
This might happen if you are upgrading the master KDC, or if your master
KDC has a disk crash.

Assuming you have configured all of your KDCs to be able to function as
either the master KDC or a slave KDC (as this document recommends), all
you need to do to make the changeover is:

If the master KDC is still running, do the following on the @emph{old}
master KDC:

@enumerate
@item
Kill the @code{kadmind} process.

@item
Disable the cron job that propagates the database.

@item
Run your database propagation script manually, to ensure that the slaves
all have the latest copy of the database.  (@xref{Propagate the Database
to Each Slave KDC}.)  If there is a need to preserve per-principal
policy information from the database, you should do a ``kdb5_util dump
-ov'' in order to preserve that information and propogate that dump file
securely by some means to the slave so that its database has the correct
state of the per-principal policy information.
@end enumerate

On the @emph{new} master KDC:

@enumerate
@item
Create a database keytab.  (@xref{Create a kadmind Keytab (optional)}.)

@item
Start the @code{kadmind} daemon.  (@xref{Start the Kerberos Daemons}.)

@item
Set up the cron job to propagate the database.  (@xref{Propagate the
Database to Each Slave KDC}.)

@item
Switch the CNAMEs of the old and new master KDCs.  (If you don't do
this, you'll need to change the @code{krb5.conf} file on every client
machine in your Kerberos realm.)

@end enumerate

@node Incremental Database Propagation,  , Switching Master and Slave KDCs, Installing KDCs
@subsection Incremental Database Propagation

At some very large sites, dumping and transmitting the database can
take more time than is desirable for changes to propagate from the
master KDC to the slave KDCs.  The incremental propagation support
added in the 1.7 release is intended to address this.

With incremental propagation enabled, all programs on the master KDC
that change the database also write information about the changes to
an ``update log'' file, maintained as a circular buffer of a certain
size.  A process on each slave KDC connects to a service on the master
KDC (currently implemented in the @code{kadmind} server) and
periodically requests the changes that have been made since the last
check.  By default, this check is done every two minutes.  If the
database has just been modified in the previous several seconds
(currently the threshold is hard-coded at 10 seconds), the slave will
not retrieve updates, but instead will pause and try again soon after.
This reduces the likelihood that incremental update queries will cause
delays for an administrator trying to make a bunch of changes to the
database at the same time.

Incremental propagation uses the following entries in the per-realm
data in the KDC config file:

@table @asis
@item @code{iprop_enable} (boolean)
If this is set to @code{true}, then incremental propagation is
enabled, and (as noted below) normal @code{kprop} propagation is
disabled.  The default is @code{false}.

@item @code{iprop_master_ulogsize} (integer)
This indicates the number of entries that should be retained in the
update log.  The default is 1000; the maximum number is 2500.

@item @code{iprop_slave_poll} (time interval)
This indicates how often the slave should poll the master KDC for
changes to the database.  The default is two minutes.

@item @code{iprop_port} (integer)
This specifies the port number to be used for incremental
propagation.  This is required in both master and slave configuration
files.

@item @code{iprop_logfile} (file name)
This specifies where the update log file for the realm database is to
be stored.  The default is to use the @code{database_name} entry from
the @code{realms} section of the config file, with @file{.ulog} appended.
(NOTE: If @code{database_name} isn't specified in the @code{realms}
section, perhaps because the LDAP database back end is being used, or
the file name is specified in the @code{dbmodules} section, then the
hard-coded default for @code{database_name} is used.  Determination of
the @code{iprop_logfile} default value will not use values from the
@code{dbmodules} section.)
@end table

Both master and slave sides must have principals named
@code{kiprop/@var{hostname}} (where @var{hostname} is, as usual, the
lower-case, fully-qualified, canonical name for the host) registered
and keys stored in the default keytab file (@file{/etc/krb5.keytab}).
@c XXX: I think the master side, at least, might be able to read the
@c key out of the database.  Test and document this.

On the master KDC side, the @code{kiprop/@var{hostname}} principal
must be listed in the @code{kadmind} ACL file @code{kadm5.acl}, and
given the @code{p} privilege.

On the slave KDC side, @code{kpropd} should be run.  When incremental
propagation is enabled, it will connect to the @code{kadmind} on the
master KDC and start requesting updates.

The normal @code{kprop} mechanism is disabled by the incremental
propagation support.  However, if the slave has been unable to fetch
changes from the master KDC for too long (network problems, perhaps),
the log on the master may wrap around and overwrite some of the
updates that the slave has not yet retrieved.  In this case, the slave
will instruct the master KDC to dump the current database out to a
file and invoke a one-time @code{kprop} propagation, with special
options to also convey the point in the update log at which the slave
should resume fetching incremental updates.  Thus, all the keytab and
ACL setup previously described for @code{kprop} propagation is still
needed.

There are several restrictions in the current implementation:

@itemize
@item
Changes to password policy objects are not propagated incrementally.
Changes to which policy applies to a principal are propagated.
@item
The master and slave must be able to initiate TCP connections in both
directions, without an intervening NAT.
@item
If the slave has an IPv6 interface address but needs to accept
connections over IPv4, the operating system needs ``dual stack'' support
(i.e. the ability to accept IPv6 and IPv4 connections on a single IPv6
listener socket).  At this time, all modern Unix-like operating systems
have dual stack support except OpenBSD.
@end itemize

@menu
* Sun/MIT Incremental Propagation Differences::  
@end menu

@node Sun/MIT Incremental Propagation Differences,  , Incremental Database Propagation, Incremental Database Propagation
@subsubsection Sun/MIT Incremental Propagation Differences

Sun donated the original code for supporting incremental database
propagation to MIT.  Some changes have been made in the MIT source
tree that will be visible to administrators.  (These notes are based
on Sun's patches.  Changes to Sun's implementation since then may not
be reflected here.)

The Sun config file support looks for @code{sunw_dbprop_enable},
@code{sunw_dbprop_master_ulogsize}, and @code{sunw_dbprop_slave_poll}.

The incremental propagation service is implemented as an ONC RPC
service.  In the Sun implementation, the service is registered with
@code{rpcbind} (also known as @code{portmapper}) and the client looks
up the port number to contact.  In the MIT implementation, where
interaction with some modern versions of @code{rpcbind} doesn't always
work well, the port number must be specified in the config file on
both the master and slave sides.

The Sun implementation hard-codes pathnames in @file{/var/krb5} for
the update log and the per-slave @code{kprop} dump files.  In the MIT
implementation, the pathname for the update log is specified in the
config file, and the per-slave dump files are stored in
@code{@value{ROOTDIR}/var/krb5kdc/slave_datatrans_@var{hostname}}.

@node Installing and Configuring UNIX Client Machines, UNIX Application Servers, Installing KDCs, Installing Kerberos V5
@section Installing and Configuring UNIX Client Machines

Client machine installation is much more straightforward than
installation of the KDCs.

@menu
* Client Programs::             
* Client Machine Configuration Files::  
@end menu

@node Client Programs, Client Machine Configuration Files, Installing and Configuring UNIX Client Machines, Installing and Configuring UNIX Client Machines
@subsection Client Programs

The Kerberized client programs are @code{kinit}, @code{klist},
@code{kdestroy}, @code{kpasswd}, and @code{ksu}.  All of these programs
are in the directory @code{@value{ROOTDIR}/bin}.

@value{COMPANY} recommends that you use @code{login.krb5} in place of
@code{/bin/login} to give your users a single-sign-on system.  You will
need to make sure your users know to use their Kerberos passwords when
they log in.

You will also need to educate your users to use the ticket management
programs @code{kinit}, @code{klist}, @code{kdestroy}, and to use the
Kerberos programs @code{ksu} and @code{kpasswd} in place of their
non-Kerberos counterparts @code{su} and @code{passwd}.

@node Client Machine Configuration Files,  , Client Programs, Installing and Configuring UNIX Client Machines
@subsection Client Machine Configuration Files

Each machine running Kerberos must have a @code{/etc/krb5.conf} file.
(@xref{krb5.conf}.)

@need 4000
Also, for most UNIX systems, you must add the appropriate Kerberos
services to each client machine's @code{/etc/services} file.  If you are
using the default configuration for @value{PRODUCT}, you should be able
to just insert the following code:

@smallexample
@group
kerberos      @value{DefaultPort}/udp    kdc    # Kerberos V5 KDC
kerberos      @value{DefaultPort}/tcp    kdc    # Kerberos V5 KDC
kerberos-adm  @value{DefaultKadmindPort}/tcp          # Kerberos 5 admin/changepw
kerberos-adm  @value{DefaultKadmindPort}/udp          # Kerberos 5 admin/changepw
krb5_prop     @value{DefaultKrbPropPort}/tcp          # Kerberos slave propagation
krb524        @value{DefaultKrb524Port}/tcp         # Kerberos 5 to 4 ticket translator
@end group
@end smallexample

@menu
* Mac OS X Configuration::      
@end menu

@node Mac OS X Configuration,  , Client Machine Configuration Files, Client Machine Configuration Files
@subsubsection Mac OS X Configuration

To install Kerberos V5 on Mac OS X and Mac OS X Server, follow the 
directions for generic Unix-based OS's, except for the 
@code{/etc/services} updates described above.  

Mac OS X and Mac OS X Server use a database called NetInfo to store
the contents of files normally found in @code{/etc}.  Instead of
modifying @code{/etc/services}, you should run the following commands
to add the Kerberos service entries to NetInfo:

@smallexample
@group
$ niutil -create . /services/kerberos
$ niutil -createprop . /services/kerberos name kerberos kdc
$ niutil -createprop . /services/kerberos port 750
$ niutil -createprop . /services/kerberos protocol tcp udp
$ niutil -create . /services/krbupdate
$ niutil -createprop . /services/krbupdate name krbupdate kreg
$ niutil -createprop . /services/krbupdate port 760
$ niutil -createprop . /services/krbupdate protocol tcp
$ niutil -create . /services/kpasswd
$ niutil -createprop . /services/kpasswd name kpasswd kpwd
$ niutil -createprop . /services/kpasswd port 761
$ niutil -createprop . /services/kpasswd protocol tcp
$ niutil -create . /services/klogin
$ niutil -createprop . /services/klogin port 543
$ niutil -createprop . /services/klogin protocol tcp
$ niutil -create . /services/eklogin
$ niutil -createprop . /services/eklogin port 2105
$ niutil -createprop . /services/eklogin protocol tcp
$ niutil -create . /services/kshell
$ niutil -createprop . /services/kshell name kshell krcmd
$ niutil -createprop . /services/kshell port 544
$ niutil -createprop . /services/kshell protocol tcp
@end group
@end smallexample

In addition to adding services to NetInfo, you must also modify the
resolver configuration in NetInfo so that the machine resolves its own
hostname as a FQDN (fully qualified domain name).  By default, Mac OS X
and Mac OS X Server machines query NetInfo to resolve hostnames before
falling back to DNS.  Because NetInfo has an unqualified name for all
the machines in the NetInfo database, the machine's own hostname will
resolve to an unqualified name.  Kerberos needs a FQDN to look up keys
in the machine's keytab file.

Fortunately, you can change the @code{lookupd} caching order to query
DNS first.  Run the following NetInfo commands and reboot the machine:

@smallexample
@group
$ niutil -create . /locations/lookupd/hosts
$ niutil -createprop . /locations/lookupd/hosts LookupOrder CacheAgent DNSAgent
 NIAgent NILAgent
@end group
@end smallexample

Once you have rebooted, you can verify that the resolver now behaves
correctly.  Compile the Kerberos 5 distribution and run:

@smallexample
@group
$ cd .../src/tests/resolve
$ ./resolve
@end group
@end smallexample

This will tell you whether or not your machine returns FQDNs on name
lookups.  If the test still fails, you can also try turning off DNS
caching.  Run the following commands and reboot:

@smallexample
@group
$ niutil -create . /locations/lookupd/hosts
$ niutil -createprop . /locations/lookupd/hosts LookupOrder DNSAgent
 CacheAgent NIAgent NILAgent
@end group
@end smallexample

The remainder of the setup of a Mac OS X client machine or application
server should be the same as for other UNIX-based systems.

@node UNIX Application Servers,  , Installing and Configuring UNIX Client Machines, Installing Kerberos V5
@section UNIX Application Servers

An application server is a host that provides one or more services over
the network.  Application servers can be ``secure'' or ``insecure.''  A
``secure'' host is set up to require authentication from every client
connecting to it.  An ``insecure'' host will still provide Kerberos
authentication, but will also allow unauthenticated clients to connect.

If you have @value{PRODUCT} installed on all of your client machines,
@value{COMPANY} recommends that you make your hosts secure, to take
advantage of the security that Kerberos authentication affords.
However, if you have some clients that do not have @value{PRODUCT}
installed, you can run an insecure server, and still take advantage of
@value{PRODUCT}'s single sign-on capability.

@menu
* The Keytab File::             
* Some Advice about Secure Hosts::  
@end menu

@node The Keytab File, Some Advice about Secure Hosts, UNIX Application Servers, UNIX Application Servers
@subsection The Keytab File

All Kerberos server machines need a @dfn{keytab} file, called
@code{/etc/krb5.keytab}, to authenticate to the KDC.  The keytab file is
an encrypted, local, on-disk copy of the host's key.  The keytab file,
like the stash file (@ref{Create the Database}) is a potential
point-of-entry for a break-in, and if compromised, would allow
unrestricted access to its host.  The keytab file should be readable
only by root, and should exist only on the machine's local disk.  The
file should not be part of any backup of the machine, unless access to
the backup data is secured as tightly as access to the machine's root
password itself.

In order to generate a keytab for a host, the host must have a principal
in the Kerberos database.  The procedure for adding hosts to the
database is described fully in the ``Adding or Modifying Principals''
section of the @cite{@value{PRODUCT} System Administrator's Guide}.
@xref{Create Host Keys for the Slave KDCs}. for a brief description.)
The keytab is generated by running @code{kadmin} and issuing the
@code{ktadd} command.

@need 1100
For example, to generate a keytab file to allow the host
trillium.@value{PRIMARYDOMAIN} to authenticate for the services
@code{host}, @code{ftp}, and @code{pop}, the administrator
@code{@value{ADMINUSER}} would issue the command (on
trillium.@value{PRIMARYDOMAIN}):

@smallexample
@group
@b{trillium%} @value{ROOTDIR}/sbin/kadmin
@b{kadmin5:} ktadd host/trillium.@value{PRIMARYDOMAIN} ftp/trillium.@value{PRIMARYDOMAIN}
@result{} pop/trillium.@value{PRIMARYDOMAIN}
@b{kadmin: Entry for principal host/trillium.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM} with
kvno 3, encryption type DES-CBC-CRC added to keytab
WRFILE:/etc/krb5.keytab.
kadmin: Entry for principal ftp/trillium.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM} with
kvno 3, encryption type DES-CBC-CRC added to keytab
WRFILE:/etc/krb5.keytab.
kadmin: Entry for principal pop/trillium.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM} with
kvno 3, encryption type DES-CBC-CRC added to keytab
WRFILE:/etc/krb5.keytab.
kadmin5:} quit
@b{trillium%}
@end group
@end smallexample

If you generate the keytab file on another host, you need to get a copy
of the keytab file onto the destination host (@code{trillium}, in the
above example) without sending it unencrypted over the network.

@node Some Advice about Secure Hosts,  , The Keytab File, UNIX Application Servers
@subsection Some Advice about Secure Hosts

@value{PRODUCT} can protect your host from certain types of break-ins,
but it is possible to install @value{PRODUCT} and still leave your host
vulnerable to attack.  Obviously an installation guide is not the place
to try to include an exhaustive list of countermeasures for every
possible attack, but it is worth noting some of the larger holes and how
to close them.

We recommend that backups of secure machines exclude the keytab file
(@code{/etc/krb5.keytab}).  If this is not possible, the backups should
at least be done locally, rather than over a network, and the backup
tapes should be physically secured.

The keytab file and any programs run by root, including the
@value{PRODUCT} binaries, should be kept on local disk.  The keytab file
should be readable only by root.

@node Upgrading Existing Kerberos V5 Installations, Bug Reports for Kerberos V5, Installing Kerberos V5, Top
@chapter Upgrading Existing @value{PRODUCT} Installations

If you already have an existing Kerberos database that you created with
a prior release of Kerberos 5, you can upgrade it to work with the
current release with the @code{kdb5_util} command.  It is only
necessary to perform this dump/undump procedure if you were running a
krb5-1.0.x KDC and are migrating to a krb5-1.1.x or newer KDC or if you
were running a krb5-1.1.x KDC and are migrating to a krb5-1.2.x or newer
KDC.  The process for upgrading a Master KDC involves the following
steps:

@enumerate

@item Stop your current KDC and administration
server processes, if any.

@item Dump your existing Kerberos database to an ASCII file with 
@code{kdb5_util}'s ``dump'' command:

@smallexample
@group
@b{shell%} cd @value{ROOTDIR}/var/krb5kdc
@b{shell%} kdb5_util dump old-kdb-dump
@b{shell%} kdb5_util dump -ov old-kdb-dump.ov
@b{shell%}
@end group
@end smallexample

@item Create a new Master KDC installation (@xref{Install the Master
KDC}.).  If you have a stash file for your current database, choose any
new master password but then copy your existing stash file to the
location specified by your kdc.conf; if you do not have a stash file for
your current database, you must choose the same master password.

@item Load your old Kerberos database into the new system with
@code{kdb5_util}'s ``load'' command:

@smallexample
@group
@b{shell%} cd @value{ROOTDIR}/var/krb5kdc
@b{shell%} kdb5_util load old-kdb-dump
@b{shell%} kdb5_util load -update old-kdb-dump.ov
@b{shell%}
@end group
@end smallexample

@end enumerate

The ``dump -ov'' and ``load -update'' commands are necessary in order to
preserve per-principal policy information, since the default dump format
filters out that information.  If you omit those steps, the loaded
database database will lose the policy information for each principal
that has a policy.

To update a Slave KDC, you must stop the old server processes on the
Slave KDC, install the new server binaries, reload the most recent slave
dump file, and re-start the server processes.

@menu
* Upgrading to Triple-DES and RC4 Encryption Keys::  
@end menu

@node Upgrading to Triple-DES and RC4 Encryption Keys,  , Upgrading Existing Kerberos V5 Installations, Upgrading Existing Kerberos V5 Installations
@section Upgrading to Triple-DES Encryption Keys

Beginning with the 1.2 release from @value{COMPANY}, Kerberos includes
a stronger encryption algorithm called ``triple DES'' -- essentially,
three applications of the basic DES encryption algorithm, greatly
increasing the resistance to a brute-force search for the key by an
attacker.  This algorithm is more secure, but encryption is much
slower.

Release 1.1 had some support for triple-DES service keys, but with
release 1.2 we have added support for user keys and session keys as
well.  Release 1.0 had very little support for multiple cryptosystems,
and some of that software may not function properly in an environment
using triple-DES as well as plain DES.

In the 1.3 release from @value{COMPANY}, Kerberos also includes the RC4
encryption alogorithm, a stream cipher symmetric key algorithm
developed in 1987 by Ronald Rivest at RSA Data Security.  Please note
that RC4 is not part of the IETF standard.

Because of the way the MIT Kerberos database is structured, the KDC
will assume that a service supports only those encryption types for
which keys are found in the database.  Thus, if a service has only a
single-DES key in the database, the KDC will not issue tickets for that
service that use triple-DES or RC4 session keys; it will instead issue
only single-DES session keys, even if other services are already
capable of using triple-DES or RC4.  So if you make sure your
application server software is updated before adding a triple-DES or
RC4 key for the service, clients should be able to talk to services at
all times during the updating process.

Normally, the listed @code{supported_enctypes} in @code{kdc.conf} are
all used when a new key is generated.  You can control this with
command-line flags to @code{kadmin} and @code{kadmin.local}.  You may
want to exclude triple-DES and RC4 by default until you have updated a
lot of your application servers, and then change the default to include
triple-DES and RC4.  We recommend that you always include
@code{des-cbc-crc} in the default list.

@node Bug Reports for Kerberos V5, Copyright, Upgrading Existing Kerberos V5 Installations, Top
@chapter Bug Reports for @value{PRODUCT}

@include send-pr.texinfo

@node Copyright,  , Bug Reports for Kerberos V5, Top
@appendix Copyright
@include copyright.texinfo

@contents
@bye