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This is krb5-install.info, produced by makeinfo version 4.5 from
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Copyright (C) 1985-2010 by the Massachusetts Institute of Technology.
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INFO-DIR-SECTION Kerberos
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* krb5-install: (krb5-install). Kerberos V5 Installation Guide
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File: krb5-install.info, Node: Mac OS X Configuration, Prev: Client Machine Configuration Files, Up: Client Machine Configuration Files
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Mac OS X Configuration
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......................
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To install Kerberos V5 on Mac OS X and Mac OS X Server, follow the
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directions for generic Unix-based OS's, except for the `/etc/services'
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updates described above.
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Mac OS X and Mac OS X Server use a database called NetInfo to store the
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contents of files normally found in `/etc'. Instead of modifying
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`/etc/services', you should run the following commands to add the
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Kerberos service entries to NetInfo:
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$ niutil -create . /services/kerberos
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$ niutil -createprop . /services/kerberos name kerberos kdc
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$ niutil -createprop . /services/kerberos port 750
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$ niutil -createprop . /services/kerberos protocol tcp udp
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$ niutil -create . /services/krbupdate
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$ niutil -createprop . /services/krbupdate name krbupdate kreg
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$ niutil -createprop . /services/krbupdate port 760
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$ niutil -createprop . /services/krbupdate protocol tcp
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$ niutil -create . /services/kpasswd
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$ niutil -createprop . /services/kpasswd name kpasswd kpwd
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$ niutil -createprop . /services/kpasswd port 761
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$ niutil -createprop . /services/kpasswd protocol tcp
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$ niutil -create . /services/klogin
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$ niutil -createprop . /services/klogin port 543
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$ niutil -createprop . /services/klogin protocol tcp
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$ niutil -create . /services/eklogin
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$ niutil -createprop . /services/eklogin port 2105
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$ niutil -createprop . /services/eklogin protocol tcp
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$ niutil -create . /services/kshell
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$ niutil -createprop . /services/kshell name kshell krcmd
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$ niutil -createprop . /services/kshell port 544
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$ niutil -createprop . /services/kshell protocol tcp
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In addition to adding services to NetInfo, you must also modify the
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resolver configuration in NetInfo so that the machine resolves its own
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hostname as a FQDN (fully qualified domain name). By default, Mac OS X
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and Mac OS X Server machines query NetInfo to resolve hostnames before
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falling back to DNS. Because NetInfo has an unqualified name for all
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the machines in the NetInfo database, the machine's own hostname will
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resolve to an unqualified name. Kerberos needs a FQDN to look up keys
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in the machine's keytab file.
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Fortunately, you can change the `lookupd' caching order to query DNS
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first. Run the following NetInfo commands and reboot the machine:
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$ niutil -create . /locations/lookupd/hosts
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$ niutil -createprop . /locations/lookupd/hosts LookupOrder CacheAgent DNSAgent
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Once you have rebooted, you can verify that the resolver now behaves
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correctly. Compile the Kerberos 5 distribution and run:
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$ cd .../src/tests/resolve
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This will tell you whether or not your machine returns FQDNs on name
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lookups. If the test still fails, you can also try turning off DNS
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caching. Run the following commands and reboot:
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$ niutil -create . /locations/lookupd/hosts
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$ niutil -createprop . /locations/lookupd/hosts LookupOrder DNSAgent
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CacheAgent NIAgent NILAgent
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The remainder of the setup of a Mac OS X client machine or application
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server should be the same as for other UNIX-based systems.
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File: krb5-install.info, Node: UNIX Application Servers, Prev: Installing and Configuring UNIX Client Machines, Up: Installing Kerberos V5
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UNIX Application Servers
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========================
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An application server is a host that provides one or more services over
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the network. Application servers can be "secure" or "insecure." A
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"secure" host is set up to require authentication from every client
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connecting to it. An "insecure" host will still provide Kerberos
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authentication, but will also allow unauthenticated clients to connect.
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If you have Kerberos V5 installed on all of your client machines,
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MIT recommends that you make your hosts secure, to take advantage of
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the security that Kerberos authentication affords. However, if you
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have some clients that do not have Kerberos V5 installed, you can run
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an insecure server, and still take advantage of Kerberos V5's single
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* Some Advice about Secure Hosts::
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File: krb5-install.info, Node: The Keytab File, Next: Some Advice about Secure Hosts, Prev: UNIX Application Servers, Up: UNIX Application Servers
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All Kerberos server machines need a "keytab" file, called
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`/etc/krb5.keytab', to authenticate to the KDC. The keytab file is an
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encrypted, local, on-disk copy of the host's key. The keytab file,
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like the stash file (*Note Create the Database::) is a potential
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point-of-entry for a break-in, and if compromised, would allow
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unrestricted access to its host. The keytab file should be readable
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only by root, and should exist only on the machine's local disk. The
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file should not be part of any backup of the machine, unless access to
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the backup data is secured as tightly as access to the machine's root
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In order to generate a keytab for a host, the host must have a principal
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in the Kerberos database. The procedure for adding hosts to the
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database is described fully in the "Adding or Modifying Principals"
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section of the `Kerberos V5 System Administrator's Guide'. *Note
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Create Host Keys for the Slave KDCs::. for a brief description.) The
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keytab is generated by running `kadmin' and issuing the `ktadd' command.
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For example, to generate a keytab file to allow the host
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trillium.mit.edu to authenticate for the services `host', `ftp', and
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`pop', the administrator `joeadmin' would issue the command (on
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trillium% /usr/local/sbin/kadmin
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kadmin5: ktadd host/trillium.mit.edu ftp/trillium.mit.edu
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=> pop/trillium.mit.edu
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kadmin: Entry for principal host/trillium.mit.edu@ATHENA.MIT.EDU with
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kvno 3, encryption type DES-CBC-CRC added to keytab
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WRFILE:/etc/krb5.keytab.
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kadmin: Entry for principal ftp/trillium.mit.edu@ATHENA.MIT.EDU with
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kvno 3, encryption type DES-CBC-CRC added to keytab
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WRFILE:/etc/krb5.keytab.
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kadmin: Entry for principal pop/trillium.mit.edu@ATHENA.MIT.EDU with
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kvno 3, encryption type DES-CBC-CRC added to keytab
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WRFILE:/etc/krb5.keytab.
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If you generate the keytab file on another host, you need to get a copy
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of the keytab file onto the destination host (`trillium', in the above
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example) without sending it unencrypted over the network.
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File: krb5-install.info, Node: Some Advice about Secure Hosts, Prev: The Keytab File, Up: UNIX Application Servers
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Some Advice about Secure Hosts
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------------------------------
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Kerberos V5 can protect your host from certain types of break-ins, but
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it is possible to install Kerberos V5 and still leave your host
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vulnerable to attack. Obviously an installation guide is not the place
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to try to include an exhaustive list of countermeasures for every
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possible attack, but it is worth noting some of the larger holes and how
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We recommend that backups of secure machines exclude the keytab file
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(`/etc/krb5.keytab'). If this is not possible, the backups should at
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least be done locally, rather than over a network, and the backup tapes
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should be physically secured.
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The keytab file and any programs run by root, including the Kerberos V5
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binaries, should be kept on local disk. The keytab file should be
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readable only by root.
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File: krb5-install.info, Node: Upgrading Existing Kerberos V5 Installations, Next: Bug Reports for Kerberos V5, Prev: Installing Kerberos V5, Up: Top
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Upgrading Existing Kerberos V5 Installations
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********************************************
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If you already have an existing Kerberos database that you created with
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a prior release of Kerberos 5, you can upgrade it to work with the
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current release with the `kdb5_util' command. It is only necessary to
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perform this dump/undump procedure if you were running a krb5-1.0.x KDC
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and are migrating to a krb5-1.1.x or newer KDC or if you were running a
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krb5-1.1.x KDC and are migrating to a krb5-1.2.x or newer KDC. The
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process for upgrading a Master KDC involves the following steps:
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1. Stop your current KDC and administration server processes, if any.
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2. Dump your existing Kerberos database to an ASCII file with
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`kdb5_util''s "dump" command:
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shell% cd /usr/local/var/krb5kdc
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shell% kdb5_util dump old-kdb-dump
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shell% kdb5_util dump -ov old-kdb-dump.ov
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3. Create a new Master KDC installation (*Note Install the Master
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KDC::.). If you have a stash file for your current database,
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choose any new master password but then copy your existing stash
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file to the location specified by your kdc.conf; if you do not
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have a stash file for your current database, you must choose the
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same master password.
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4. Load your old Kerberos database into the new system with
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`kdb5_util''s "load" command:
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shell% cd /usr/local/var/krb5kdc
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shell% kdb5_util load old-kdb-dump
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shell% kdb5_util load -update old-kdb-dump.ov
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The "dump -ov" and "load -update" commands are necessary in order to
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preserve per-principal policy information, since the default dump format
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filters out that information. If you omit those steps, the loaded
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database database will lose the policy information for each principal
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To update a Slave KDC, you must stop the old server processes on the
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Slave KDC, install the new server binaries, reload the most recent slave
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dump file, and re-start the server processes.
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* Upgrading to Triple-DES and RC4 Encryption Keys::
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File: krb5-install.info, Node: Upgrading to Triple-DES and RC4 Encryption Keys, Prev: Upgrading Existing Kerberos V5 Installations, Up: Upgrading Existing Kerberos V5 Installations
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Upgrading to Triple-DES Encryption Keys
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=======================================
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Beginning with the 1.2 release from MIT, Kerberos includes a stronger
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encryption algorithm called "triple DES" - essentially, three
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applications of the basic DES encryption algorithm, greatly increasing
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the resistance to a brute-force search for the key by an attacker.
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This algorithm is more secure, but encryption is much slower.
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Release 1.1 had some support for triple-DES service keys, but with
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release 1.2 we have added support for user keys and session keys as
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well. Release 1.0 had very little support for multiple cryptosystems,
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and some of that software may not function properly in an environment
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using triple-DES as well as plain DES.
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In the 1.3 release from MIT, Kerberos also includes the RC4 encryption
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alogorithm, a stream cipher symmetric key algorithm developed in 1987
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by Ronald Rivest at RSA Data Security. Please note that RC4 is not
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part of the IETF standard.
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Because of the way the MIT Kerberos database is structured, the KDC
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will assume that a service supports only those encryption types for
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which keys are found in the database. Thus, if a service has only a
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single-DES key in the database, the KDC will not issue tickets for that
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service that use triple-DES or RC4 session keys; it will instead issue
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only single-DES session keys, even if other services are already
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capable of using triple-DES or RC4. So if you make sure your
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application server software is updated before adding a triple-DES or
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RC4 key for the service, clients should be able to talk to services at
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all times during the updating process.
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Normally, the listed `supported_enctypes' in `kdc.conf' are all used
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when a new key is generated. You can control this with command-line
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flags to `kadmin' and `kadmin.local'. You may want to exclude
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triple-DES and RC4 by default until you have updated a lot of your
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application servers, and then change the default to include triple-DES
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and RC4. We recommend that you always include `des-cbc-crc' in the
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File: krb5-install.info, Node: Bug Reports for Kerberos V5, Next: Copyright, Prev: Upgrading Existing Kerberos V5 Installations, Up: Top
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Bug Reports for Kerberos V5
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***************************
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In any complex software, there will be bugs. If you have successfully
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built and installed Kerberos V5, please use the `krb5-send-pr' program
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to fill out a Problem Report should you encounter any errors in our
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Bug reports that include proposed fixes are especially welcome. If you
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do include fixes, please send them using either context diffs or unified
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diffs (using `diff -c' or `diff -u', respectively). Please be careful
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when using "cut and paste" or other such means to copy a patch into a
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bug report; depending on the system being used, that can result in
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converting TAB characters into spaces, which makes applying the patches
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The `krb5-send-pr' program is installed in the directory
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The `krb5-send-pr' program enters the problem report into our Problem
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Report Management System (PRMS), which automatically assigns it to the
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engineer best able to help you with problems in the assigned category.
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The `krb5-send-pr' program will try to intelligently fill in as many
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fields as it can. You need to choose the "category", "class",
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"severity", and "priority" of the problem, as well as giving us as much
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information as you can about its exact nature.
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The PR category will be one of:
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krb5-admin krb5-appl krb5-build krb5-clients
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krb5-doc krb5-kdc krb5-libs krb5-misc
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Choose the category that best describes the area under which your
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The class can be "sw-bug", "doc-bug", "change-request", or "support".
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The first two are exactly as their names imply. Use change-request
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when the software is behaving according to specifications, but you want
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to request changes in some feature or behavior. The support class is
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intended for more general questions about building or using Kerberos V5.
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The severity of the problem indicates the problem's impact on the
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usability of Kerberos V5. If a problem is "critical", that means the
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product, component or concept is completely non-operational, or some
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essential functionality is missing, and no workaround is known. A
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"serious" problem is one in which the product, component or concept is
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not working properly or significant functionality is missing. Problems
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that would otherwise be considered critical are rated serious when a
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workaround is known. A "non-critical" problem is one that is indeed a
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problem, but one that is having a minimal effect on your ability to use
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Kerberos V5. E.g., The product, component or concept is working in
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general, but lacks features, has irritating behavior, does something
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wrong, or doesn't match its documentation. The default severity is
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The priority indicates how urgent this particular problem is in
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relation to your work. Note that low priority does not imply low
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importance. A priority of "high" means a solution is needed as soon as
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possible. A priority of "medium" means the problem should be solved no
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later than the next release. A priority of "low" means the problem
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should be solved in a future release, but it is not important to your
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work how soon this happens. The default priority is medium.
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Note that a given severity does not necessarily imply a given priority.
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For example, a non-critical problem might still have a high priority if
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you are faced with a hard deadline. Conversely, a serious problem might
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have a low priority if the feature it is disabling is one that you do
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It is important that you fill in the release field and tell us what
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changes you have made, if any.
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A sample filled-out form from a company named "Toasters, Inc." might
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To: krb5-bugs@mit.edu
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Subject: misspelled "Kerberos" in title of installation guide
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X-send-pr-version: 3.99
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>Originator: Jeffrey C. Gilman Bigler
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>Synopsis: Misspelled "Kerberos" in title of installation guide
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>Severity: non-critical
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>Release: 1.0-development
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<machine, os, target, libraries (multiple lines)>
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System: ULTRIX imbrium 4.2 0 RISC
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Misspelled "Kerberos" in title of "Kerboros V5 Installation Guide"
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Correct the spelling.
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If the `krb5-send-pr' program does not work for you, or if you did not
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get far enough in the process to have an installed and working
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`krb5-send-pr', you can generate your own form, using the above as an
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doc/krb5-install.info-3
