\input texinfo-suppl.tex        % contains @doubleleftarrow{} definition
                                % this line must come *before* \input texinfo
\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
@c %**end of header

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

@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

@iftex
@include copyright.texinfo
@end iftex
@end titlepage

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

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

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

@node Copyright, Introduction, Top, Top
@unnumbered Copyright
@include copyright.texinfo

@end ifinfo

@node Introduction, Realm Configuration Decisions, Copyright, 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.

@include document-list.texinfo

@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

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

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

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.

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

Chapter six describes our problem reporting system.

The appendices give sample configuration files.

@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.

@item
Whether you need backward compatibility with Kerberos V4.
@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

Mapping hostnames onto Kerberos realms is done in one of two ways.

The first mechanism, which has been in use for years in MIT-based
Kerberos distributions, works through a set of rules in
the @code{krb5.conf} configuration file.  (@xref{krb5.conf}.)  You can
specify mappings for an entire domain or subdomain, and/or on a
hostname-by-hostname basis.  Since greater specificity takes precedence,
you would do this by specifying the mappings for a given domain or
subdomain and listing the exceptions.

The @value{PRODUCT} System Administrator's Guide contains a thorough
description of the parts of the @code{krb5.conf} file and what may be
specified in each.  A sample @code{krb5.conf} file appears in
@ref{krb5.conf}.  You should be able to use this file, substituting the
relevant information for your Kerberos installation for the samples.

The second mechanism, recently introduced into the MIT code base but not
currently used by default, works by looking up the information in
special @code{TXT} records in the Domain Name Service.  If this
mechanism is enabled on the client, it will try to look up a @code{TXT}
record for the DNS name formed by putting the prefix @code{_kerberos} in
front of the hostname in question.  If that record is not found, it will
try using @code{_kerberos} and the host's domain name, then its parent
domain, and so forth.  So for the hostname
BOSTON.ENGINEERING.FOOBAR.COM, the names looked up would be:

@smallexample
_kerberos.boston.engineering.foobar.com
_kerberos.engineering.foobar.com
_kerberos.foobar.com
_kerberos.com
@end smallexample

The value of the first TXT record found is taken as the realm name.
(Obviously, this doesn't work all that well if a host and a subdomain
have the same name, and different realms.  For example, if all the hosts
in the ENGINEERING.FOOBAR.COM domain are in the ENGINEERING.FOOBAR.COM
realm, but a host named ENGINEERING.FOOBAR.COM is for some reason in
another realm.  In that case, you would set up TXT records for all
hosts, rather than relying on the fallback to the domain name.)

Even if you do not choose to use this mechanism within your site, you
may wish to set up anyways, for use when interacting with other sites.

@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 88 for the
KDC@footnote{Kerberos V4 used port 750.  If necessary, you can run on
both ports for backward compatibility.}  and port 749 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

@value{COMPANY} recommends that your KDCs have a predefined set of
CNAME records (DNS hostname aliases), such as @code{@value{KDCSERVER}}
for the master KDC and
@code{@value{KDCSLAVE1}}, @code{@value{KDCSLAVE2}}, @dots{} for the
slave KDCs.  This way, if you need to swap a machine, you only need to
change a DNS entry, rather than having to change hostnames.

A new mechanism for locating KDCs of a realm through DNS has been added
to the @value{COMPANY} @value{PRODUCT} distribution.  A relatively new
record type called @code{SRV} has been added to DNS.  Looked up by a
service name and a domain name, these records indicate the hostname and
port number to contact for that service, optionally with weighting and
prioritization.  (See RFC 2782 if you want more information.  You can
follow the example below for straightforward cases.)

The use with Kerberos is fairly straightforward.  The domain name used
in the SRV record name is the domain-style Kerberos realm name.  (It is
possible to have Kerberos realm names that are not DNS-style names, but
we don't recommend it for Internet use, and our code does not support it
well.)  Several different Kerberos-related service names are used:

@table @code
@item _kerberos._udp
This is for contacting any KDC.  This entry will be used the most often.
Normally you should list ports 88 and 750 on each of your KDCs.

@item _kerberos-master._udp
This entry should refer to those KDCs, if any, that will immediately see
password changes to the Kerberos database.  This entry is used only in
one case, when the user is logging in and the password appears to be
incorrect; the master KDC is then contacted, and the same password used
to try to decrypt the response, in case the user's password had recently
been changed and the first KDC contacted hadn't been updated.  Only if
that fails is an ``incorrect password'' error given.

If you have only one KDC, or for whatever reason there is no accessible
KDC that would get database changes faster than the others, you do not
need to define this entry.

@item _kerberos-adm._tcp
This should list port 749 on your master KDC.  Support for it is not
complete at this time, but it will eventually be used by the
@code{kadmin} program and related utilities.  For now, you will also
need the @code{admin_server} entry in @code{krb5.conf}.

@item _kpasswd._udp
This should list port 464 on your master KDC.  It is used when a user
changes her password.

@end table

Be aware, however, that the DNS SRV specification requires that the
hostnames listed be the canonical names, not aliases.  So, for example,
you might include the following records in your (BIND-style) zone file:

@smallexample
$ORIGIN foobar.com.
_kerberos               TXT       "FOOBAR.COM"
kerberos                CNAME     daisy
kerberos-1              CNAME     use-the-force-luke
kerberos-2              CNAME     bunny-rabbit
_kerberos._udp          SRV       0 0 88 daisy
                        SRV       0 0 88 use-the-force-luke
                        SRV       0 0 88 bunny-rabbit
_kerberos-master._udp   SRV       0 0 88 daisy
_kerberos-adm._tcp      SRV       0 0 749 daisy
_kpasswd._udp           SRV       0 0 464 daisy
@end smallexample

As with the DNS-based mechanism for determining the Kerberos realm of a
host, we recommend distributing the information this way for use by
other sites that may want to interact with yours using Kerberos, even if
you don't immediately make use of it within your own site.  If you
anticipate installing a very large number of machines on which it will
be hard to update the Kerberos configuration files, you may wish to do
all of your Kerberos service lookups via DNS and not put the information
(except for @code{admin_server} as noted above) in future versions of
your @code{krb5.conf} files at all.  Eventually, we hope to phase out
the listing of server hostnames in the client-side configuration files;
making preparations now will make the transition easier in the future.

@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::  
@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::  
* Create the Database::         
* Add Administrators to the Acl File::  
* Add Administrators to the Kerberos Database::  
* Create a kadmind Keytab::     
* Start the Kerberos Daemons::  
@end menu

@node Edit the Configuration Files, Create the Database, Install the Master KDC, Install the Master KDC
@subsubsection Edit the Configuration Files

Modify the configuration files, @code{/etc/krb5.conf}
(@pxref{krb5.conf}) and @code{@value{ROOTDIR}/var/krb5kdc/kdc.conf}
(@pxref{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}.

Among the settings in your @code{/etc/krb5.conf} file, be sure to create
a @code{[logging]} stanza so that the KDC and kadmind will generate
logging output.  For example:

@smallexample
@group
[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 Create the Database, Add Administrators to the Acl File, Edit the Configuration Files, 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.

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
@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.  The
filename should match the value you have set for ``acl_file'' in your
@code{kdc.conf} file.  The default file name is @samp{kadm5.acl}.  The
format of the file is:

@smallexample
Kerberos principal      permissions     optional target principal
@end smallexample

The Kerberos principal (and optional target principal) can include the
``@b{*}'' wildcard, so if you want any principal with the instance
``admin'' to have full permissions on the database, you could use the
principal ``@code{*/admin@@REALM}'' where ``REALM'' is your Kerberos
realm.

Note:  a common use of an @i{admin} instance is so you can grant
separate permissions (such as administrator access to the Kerberos
database) to a separate Kerberos principal.  For example, the user
@code{@value{ADMINUSER}} might have a principal for his administrative
use, called @code{@value{ADMINUSER}/admin}.  This way,
@code{@value{ADMINUSER}} would obtain @code{@value{ADMINUSER}/admin}
tickets only when he actually needs to use those permissions.  Refer to
the @value{PRODUCT} Administrator's Guide or the @value{PRODUCT} User's
Guide for more detailed explanations of @dfn{principals} and
@dfn{instances}.

The permissions (acls) recognized in the acl file 
are the following:

@table @b
@itemx a
allows the addition of principals or policies in the database.
@itemx A
prohibits the addition of principals or policies in the database.
@itemx d
allows the deletion of principals or policies in the database.
@itemx D
prohibits the deletion of principals or policies in the database.
@itemx m    
allows the modification of principals or policies in the database.
@itemx M
prohibits the modification of principals or policies in the database.
@itemx c
allows the changing of passwords for principals in the database.
@itemx C
prohibits the changing of passwords for principals in the database.
@itemx i
allows inquiries to the database.
@itemx I
prohibits inquiries to the database.
@itemx l
allows the listing of principals or policies in the database.
@itemx L
prohibits the listing of principals or policies in the database.
@itemx *
Short for all privileges (admcil).
@itemx x
Short for all privileges (admcil); identical to ``*''.
@end table

To give the principal @code{*/admin@@@value{PRIMARYREALM}} permission to
change all of the database permissions on any principal permissions, you
would place the following line in the file:

@smallexample
*/admin@@@value{PRIMARYREALM}  *
@end smallexample

To give the principal @code{@value{ADMINUSER}@@@value{PRIMARYREALM}}
permission to add, list, and inquire about any principal that has the
instance ``root'', you would add the following line to the acl file:

@smallexample
@value{ADMINUSER}@@@value{PRIMARYREALM}  ali  */root@@@value{PRIMARYREALM}
@end smallexample

@node Add Administrators to the Kerberos Database, Create a kadmind Keytab, 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{WARNING: no policy specified for "admin/admin@@@value{PRIMARYREALM}";
defaulting to no policy.}
@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
@b{Principal "admin/admin@@@value{PRIMARYREALM}" created.
kadmin.local:}
@end group
@end smallexample



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

The kadmind keytab is the key that kadmind will use to decrypt
administrators' Kerberos tickets to determine whether or not it should
give them 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@@@value{PRIMARYREALM} with
     kvno 3, encryption type DES-CBC-CRC added to keytab
     WRFILE:@value{ROOTDIR}/var/krb5kdc/kadm5.keytab.
Entry for principal kadmin/changepw@@@value{PRIMARYREALM} with
     kvno 3, encryption type DES-CBC-CRC added to keytab
     WRFILE:@value{ROOTDIR}/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, 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}.
(See @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{WARNING: no policy specified for "host/@value{KDCSERVER}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}";
defaulting to no policy.
Principal "host/@value{KDCSERVER}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}" created.
kadmin:} addprinc -randkey host/@value{KDCSLAVE1}.@value{PRIMARYDOMAIN}
@b{WARNING: no policy specified for "host/@value{KDCSLAVE1}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}";
defaulting to no policy.
Principal "host/@value{KDCSLAVE1}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}" created.}
@b{kadmin:} addprinc -randkey host/@value{KDCSLAVE2}.@value{PRIMARYDOMAIN}
@b{WARNING: no policy specified for "host/@value{KDCSLAVE2}.@value{PRIMARYDOMAIN}@@@value{PRIMARYREALM}";
defaulting to no policy.
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 lines to @code{/etc/inetd.conf} file on each KDC
(the line beginnng with @result{} is a continuation of the previous
line):

@smallexample
@group
krb5_prop stream tcp nowait root @value{ROOTDIR}/sbin/kpropd kpropd
eklogin   stream tcp nowait root @value{ROOTDIR}/sbin/klogind 
@result{} klogind -k -c -e
@end group
@end smallexample

@noindent
The first line sets up the @code{kpropd} database propagation daemon.
The second line sets up the @code{eklogin} daemon, allowing
Kerberos-authenticated, encrypted rlogin to the KDC.

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)
eklogin         2105/tcp              # Kerberos encrypted rlogin
@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 -R "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
@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.

@need 4700
@value{COMPANY} recommends that your KDCs use the following
@code{/etc/inetd.conf} file.  (Note:  each line beginning with @result{}
is a continuation of the previous line.):

@smallexample
@group
#
# Configuration file for inetd(1M).  See inetd.conf(4).
#
# To re-configure the running inetd process, edit this file, then
# send the inetd process a SIGHUP.
#
# Syntax for socket-based Internet services:
#  <service_name> <socket_type> <proto> <flags> <user> 
@result{} <server_pathname> <args>
#
# Syntax for TLI-based Internet services:
#
#  <service_name> tli <proto> <flags> <user> <server_pathname> <args>
#
# Ftp and telnet are standard Internet services.
#
# This machine is a secure Kerberos Key Distribution Center (KDC).  
# Services are limited.
#
#
# Time service is used for clock synchronization.
#
time    stream  tcp     nowait  root    internal
time    dgram   udp     wait    root    internal
#
# Limited Kerberos services
#
krb5_prop stream tcp nowait root @value{ROOTDIR}/sbin/kpropd  kpropd
eklogin   stream tcp nowait root @value{ROOTDIR}/sbin/klogind 
@result{} klogind -5 -c -e
@end group
@end smallexample

@node Switching Master and Slave KDCs,  , 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}.)  As of the 1.2.2 release, it is no longer necessary
to use ``kdb5_util dump -ov'' in order to preserve per-principal policy
information, as the default dump format now supports it.  Note you
should update your slaves prior to your master, so that they will
understand the new dump format.  (This is a good policy anyway.)
@end enumerate

On the @emph{new} master KDC:

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

@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 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{login.krb5}, @code{rlogin},
@code{telnet}, @code{ftp}, @code{rcp}, @code{rsh}, @code{kinit},
@code{klist}, @code{kdestroy}, @code{kpasswd}, @code{ksu}, and
@code{krb524init}.  All of these programs are in the directory
@code{@value{ROOTDIR}/bin}, except for @code{login.krb5} which is in
@code{@value{ROOTDIR}/sbin}.

You will probably want to have your users put @code{@value{ROOTDIR}/bin}
ahead of @code{/bin} and @code{/usr/bin} in their paths, so they will by
default get the @value{PRODUCT} versions of @code{rlogin},
@code{telnet}, @code{ftp}, @code{rcp}, and @code{rsh}.

@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},
@c @code{krb524init}, 
@code{klist}, @code{kdestroy}, and to use the Kerberos programs
@c @code{pfrom},
@code{ksu}, and @code{kpasswd} in place of their non-Kerberos
counterparts
@c @code{from}
@code{su}, @code{passwd}, and @code{rdist}.

@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
#
# Note --- if you are using Kerberos V4 and you either:
#
#    (a) haven't converted all your master or slave KDCs to V5, or
#
#    (b) are worried about inter-realm interoperability with other KDC's
#        that are still using V4 
#
# you will need to switch the "kerberos" service to port 750 and create a
# "kerberos-sec" service on port 88.
#
kerberos      88/udp    kdc    # Kerberos V5 KDC
kerberos      88/tcp    kdc    # Kerberos V5 KDC
klogin        543/tcp          # Kerberos authenticated rlogin
kshell        544/tcp   cmd    # and remote shell
kerberos-adm  749/tcp          # Kerberos 5 admin/changepw
kerberos-adm  749/udp          # Kerberos 5 admin/changepw
krb5_prop     754/tcp          # Kerberos slave propagation
@c kpop          1109/tcp         # Pop with Kerberos
eklogin       2105/tcp         # Kerberos auth. & encrypted rlogin
krb524        4444/tcp         # Kerberos 5 to 4 ticket translator
@end group
@end smallexample

@noindent As described in the comments in the above code, if your master
KDC or any of your slave KDCs is running Kerberos V4, (or if you will be
authenticating to any Kerberos V4 KDCs in another realm) you will need
to switch the port number for @code{kerberos} to 750 and create a
@code{kerberos-sec} service (tcp and udp) on port 88, so the Kerberos
V4 KDC(s) will continue to work properly.

@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 on capability.

@menu
* Server Programs::             
* Server Configuration Files::  
* The Keytab File::             
* Some Advice about Secure Hosts::  
@end menu

@node Server Programs, Server Configuration Files, UNIX Application Servers, UNIX Application Servers
@subsection Server Programs

Just as @value{PRODUCT} provided its own Kerberos-enhanced versions of
client UNIX network programs, @value{PRODUCT} also provides
Kerberos-enhanced versions of server UNIX network daemons.  These are
@code{ftpd}, @code{klogind}, @code{kshd}, and @code{telnetd}.
@c @code{popper}, 
These programs are installed in the directory
@code{@value{ROOTDIR}/sbin}.  You may want to add this directory to
root's path.

@node Server Configuration Files, The Keytab File, Server Programs, UNIX Application Servers
@subsection Server Configuration Files

For a @emph{secure} server, make the following changes to
@code{/etc/inetd.conf}:

Find and comment out any lines for the services @code{ftp},
@code{telnet}, @code{shell}, @code{login}, and @code{exec}.

@need 1800
Add the following lines.  (Note:  each line beginning with @result{} is
a continuation of the previous line.)

@smallexample
@group
klogin  stream  tcp  nowait  root  @value{ROOTDIR}/sbin/klogind
@result{} klogind -k -c
eklogin stream  tcp  nowait  root  @value{ROOTDIR}/sbin/klogind
@result{} klogind -k -c -e
kshell  stream  tcp  nowait  root  @value{ROOTDIR}/sbin/kshd
@result{} kshd -k -c -A
ftp     stream  tcp  nowait  root  @value{ROOTDIR}/sbin/ftpd
@result{} ftpd -a
telnet  stream  tcp  nowait  root  @value{ROOTDIR}/sbin/telnetd
@result{} telnetd -a valid
@end group
@end smallexample

For an @emph{insecure} server, make the following changes instead to
@code{/etc/inetd.conf}:

@need 1800
Find and comment out any lines for the services @code{ftp} and
@code{telnet}.

Add the following lines.  (Note:  each line beginning with @result{} is
a continuation of the previous line.)
@smallexample
@group
klogin  stream  tcp  nowait  root  @value{ROOTDIR}/sbin/klogind
@result{} klogind -k -c
eklogin stream  tcp  nowait  root  @value{ROOTDIR}/sbin/klogind
@result{} klogind -k -c -e
kshell  stream  tcp  nowait  root  @value{ROOTDIR}/sbin/kshd
@result{} kshd -k -c -A
ftp     stream  tcp  nowait  root  @value{ROOTDIR}/sbin/ftpd
@result{} ftpd
telnet  stream  tcp  nowait  root  @value{ROOTDIR}/sbin/telnetd
@result{} telnetd -a none
@end group
@end smallexample

@node The Keytab File, Some Advice about Secure Hosts, Server Configuration Files, 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.  If you
have installed the @value{PRODUCT} client programs, you can use
encrypted @code{rcp}.

@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.

As stated earlier in this section, @value{COMPANY} recommends that on a
secure host, you disable the standard @code{ftp}, @code{login},
@code{telnet}, @code{shell}, and @code{exec} services in
@code{/etc/inetd.conf}.  We also recommend that secure hosts have an empty
@code{/etc/hosts.equiv} file and that there not be a @code{.rhosts} file
in @code{root}'s home directory.  You can grant Kerberos-authenticated
root access to specific Kerberos principals by placing those principals
in the file @code{.k5login} in root's home directory.

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.

Finally, 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.  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 dump format in
releases prior to 1.2.2 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 Encryption Keys::  
@end menu

@node Upgrading to Triple-DES 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 MIT, 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.  We expect to
add other, faster encryption algorithms at some point in the future.

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.

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 session keys; it will instead issue only
single-DES session keys, even if other services are already capable of
using triple-DES.  So if you make sure your application server software
is updated before adding a triple-DES 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 by default until you have updated a lot of
your application servers, and then change the default to include
triple-DES.  We recommend that you always include @code{des-cbc-crc} in
the default list.

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

@include send-pr.texinfo

@node Files,  , Bug Reports for Kerberos V5, Top
@appendix Files

@menu
* krb5.conf::                   
* kdc.conf::                    
@end menu

@node krb5.conf, kdc.conf, Files, Files
@appendixsec krb5.conf

Here is an example @code{krb5.conf} file:

@smallexample
@group
[libdefaults]
    ticket_lifetime = 600
    default_realm = @value{PRIMARYREALM}
    default_tkt_enctypes = des3-hmac-sha1 des-cbc-crc
    default_tgs_enctypes = des3-hmac-sha1 des-cbc-crc

[realms]
    @value{PRIMARYREALM} = @{
        kdc = @value{KDCSERVER}.@value{PRIMARYDOMAIN}:88
        kdc = @value{KDCSLAVE1}.@value{PRIMARYDOMAIN}:88
        kdc = @value{KDCSLAVE2}.@value{PRIMARYDOMAIN}:88
        admin_server = @value{KDCSERVER}.@value{PRIMARYDOMAIN}:749
        default_domain = @value{PRIMARYDOMAIN}
    @}

[domain_realm]
    .@value{PRIMARYDOMAIN} = @value{PRIMARYREALM}
    @value{PRIMARYDOMAIN} = @value{PRIMARYREALM}
@end group
@end smallexample

For the KDCs, add a section onto the end of the @code{krb5.conf} file
telling how logging information should be stored, as in the following
example:

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

@iftex
@vfill
@end iftex
@page

@node kdc.conf,  , krb5.conf, Files
@appendixsec kdc.conf

Here's an example of a kdc.conf file:

@smallexample
@group
[kdcdefaults]
    kdc_ports = 88,750

[realms]
    @value{PRIMARYREALM} = @{
        database_name = @value{ROOTDIR}/var/krb5kdc/principal
        admin_keytab = @value{ROOTDIR}/var/krb5kdc/kadm5.keytab
        acl_file = @value{ROOTDIR}/var/krb5kdc/kadm5.acl
        dict_file = @value{ROOTDIR}/var/krb5kdc/kadm5.dict
        key_stash_file = @value{ROOTDIR}/var/krb5kdc/.k5.@value{PRIMARYREALM}
        kadmind_port = 749
        max_life = 10h 0m 0s
        max_renewable_life = 7d 0h 0m 0s
        master_key_type = des3-hmac-sha1
        supported_enctypes = des3-hmac-sha1:normal des-cbc-crc:normal
    @}
@end group
@end smallexample

To add Kerberos V4 support, add @code{des-cbc-crc:v4} to the
@code{supported_enctypes} line.

@menu
* Encryption Types and Salt Types::  
@end menu

@node Encryption Types and Salt Types,  , kdc.conf, kdc.conf
@appendixsubsec Encryption Types and Salt Types

Currently, @value{PRODUCT} supports only DES and triple-DES encryption.
The encoding types include
@code{des-cbc-crc} and @code{des3-cbc-sha1}.  The @dfn{salt} is
additional information encoded within the key that tells what kind of
key it is.  The only salts that you will be likely to encounter are:

@itemize @bullet
@item @dfn{normal}, which @value{COMPANY} recommends using for all of
your @value{PRODUCT} keys

@item @dfn{v4}, which is necessary only for compatibility with a v4 KDC
or a v4 version of @code{kinit}, and then only with @code{des-cbc-crc}
encryption

@item @dfn{afs}, which you will never need to generate, and which you will
encounter only if you dump an AFS database into a Kerberos database
@end itemize

Support for additional encryption types is planned in the future.

@contents
@bye
