This is Info file krb5-install.info, produced by Makeinfo-1.55 from the input file install.texinfo.  File: krb5-install.info, Node: Extract Host Keytabs for the KDCs, Next: Set Up the Slave KDCs for Database Propagation, Prev: Create Host Keys for the Slave KDCs, Up: Install the Slave KDCs 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 kerberos.mit.edu, you would execute the following command: kadmin: ktadd host/kerberos.mit.edu kadmin: Entry for principal host/kerberos.mit.edu@ATHENA.MIT.EDU with kvno 1, encryption type DES-CBC-CRC added to keytab WRFILE:/etc/v5srvtab. kadmin: Note that the principal must exist in the Kerberos database in order to extract the keytab.  File: krb5-install.info, Node: Set Up the Slave KDCs for Database Propagation, Prev: Extract Host Keytabs for the KDCs, Up: Install the Slave KDCs Set Up the Slave KDCs for Database Propagation .............................................. The database is propagated from the master KDC to the slave KDCs via the `kpropd' daemon. To set up propagation, create a file on each KDC, named `/usr/krb5/lib/krb5kdc/kpropd.acl', containing the principals for each of the KDCs. For example, if the master KDC were `kerberos.mit.edu', the slave KDCs were `kerberos-1.mit.edu' and `kerberos-2.mit.edu', and the realm were `ATHENA.MIT.EDU', then the file's contents would be: host/kerberos.mit.edu@ATHENA.MIT.EDU host/kerberos-1.mit.edu@ATHENA.MIT.EDU host/kerberos-2.mit.edu@ATHENA.MIT.EDU Then, add the following lines to `/etc/inetd.conf' file on each KDC (the line beginnng with => is a continuation of the previous line): krb5_prop stream tcp nowait root /usr/krb5/sbin/kpropd kpropd eklogin stream tcp nowait root /usr/krb5/sbin/klogind => klogind -k -c -e The first line sets up the `kpropd' database propagation daemon. The second line sets up the `eklogin' daemon, allowing Kerberos-authenticated, encrypted rlogin to the KDC. You also need to add the following lines to `/etc/services' on each KDC: 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  File: krb5-install.info, Node: Back on the Master KDC, Next: Finish Installing the Slave KDCs, Prev: Install the Slave KDCs, Up: Installing KDCs 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::  File: krb5-install.info, Node: Propagate the Database to Each Slave KDC, Prev: Back on the Master KDC, Up: Back on the Master KDC Propagate the Database to Each Slave KDC ........................................ First, create a dump of the database on the master KDC, as follows: shell% /usr/krb5/sbin/kdb5_util dump /usr/krb5/lib/krb5kdc/slave_datatrans shell% Next, you need to manually propagate the database to each slave KDC, as in the following example. (The lines beginning with => are continuations of the previous line.): /usr/krb5/sbin/kprop -f /usr/krb5/lib/krb5kdc/slave_datatrans => kerberos-1.mit.edu /usr/krb5/sbin/kprop -f /usr/krb5/lib/krb5kdc/slave_datatrans => kerberos-2.mit.edu 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 => is a continuation of the previous line. Remember that you need to replace /usr/krb5 with the name of the directory in which you installed Kerberos V5.) #!/bin/sh kdclist = "kerberos-1.mit.edu kerberos-2.mit.edu" /usr/krb5/sbin/kdb5_util -R "dump => /usr/krb5/lib/krb5kdc/slave_datatrans" for kdc in $kdclist do /usr/krb5/sbin/kprop -f /usr/krb5/lib/krb5kdc/slave_datatrans $kdc done You will need to set up a cron job to run this script at the intervals you decided on earlier (*Note Database Propagation::.)  File: krb5-install.info, Node: Finish Installing the Slave KDCs, Next: Add Kerberos Principals to the Database, Prev: Back on the Master KDC, Up: Installing KDCs 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 `krb5kdc' daemon. * Menu: * Create Stash Files on the Slave KDCs:: * Start the krb5kdc Daemon on Each KDC::  File: krb5-install.info, Node: Create Stash Files on the Slave KDCs, Next: Start the krb5kdc Daemon on Each KDC, Prev: Finish Installing the Slave KDCs, Up: Finish Installing the Slave KDCs Create Stash Files on the Slave KDCs .................................... Create stash files, by issuing the following commands on each slave KDC: shell% kdb5_util stash kdb5_util: Cannot find/read stored master key while reading master key kdb5_util: Warning: proceeding without master key Enter KDC database master key: <= Enter the database master key. shell% 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.  File: krb5-install.info, Node: Start the krb5kdc Daemon on Each KDC, Prev: Create Stash Files on the Slave KDCs, Up: Finish Installing the Slave KDCs Start the krb5kdc Daemon on Each KDC .................................... The final step in configuing your slave KDCs is to run the KDC daemon: shell% /usr/krb5/sbin/krb5kdc As with the master KDC, you will probably want to add this command to the KDCs' `/etc/rc' or `/etc/inittab' files, so they will start the krb5kdc daemon automatically at boot time.  File: krb5-install.info, Node: Add Kerberos Principals to the Database, Next: Limit Access to the KDCs, Prev: Finish Installing the Slave KDCs, Up: Installing KDCs Add Kerberos Principals to the Database --------------------------------------- Once your KDCs are set up and running, you are ready to use `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 Kerberos V5 System Administrator's Guide. (*Note Create Host Keys for the Slave KDCs:: for a brief description.) The keytab is generated by running `kadmin' and issuing the `ktadd' command.  File: krb5-install.info, Node: Limit Access to the KDCs, Next: Switching Master and Slave KDCs, Prev: Add Kerberos Principals to the Database, Up: Installing KDCs Limit Access to the KDCs ------------------------ To limit the possibility that your Kerberos database could be compromised, MIT 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. MIT recommends that your KDCs use the following `/etc/inetd.conf' file. (Note: each line beginning with => is a continuation of the previous line.): # # 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: # => # # Syntax for TLI-based Internet services: # # tli # # 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 /usr/krb5/sbin/kpropd kpropd eklogin stream tcp nowait root /usr/krb5/sbin/klogind => klogind -k -c -e  File: krb5-install.info, Node: Switching Master and Slave KDCs, Prev: Limit Access to the KDCs, Up: Installing KDCs 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 *old* master KDC: 1. Kill the `kadmind' process. 2. Disable the cron job that propagates the database. 3. Run your database propagation script manually, to ensure that the slaves all have the latest copy of the database. (*Note Propagate the Database to Each Slave KDC::.) On the *new* master KDC: 1. Create a database keytab. (*Note Create a kadmind Keytab::.) 2. Start the `kadmind' daemon. (*Note Start the Kerberos Daemons::.) 3. Set up the cron job to propagate the database. (*Note Propagate the Database to Each Slave KDC::.) 4. Switch the cnames of the old and new master KDCs. (If you don't do this, you'll need to change the `krb5.conf' file on every client machine in your Kerberos realm.)  File: krb5-install.info, Node: Installing and Configuring UNIX Client Machines, Next: UNIX Application Servers, Prev: Installing KDCs, Up: Installing Kerberos V5 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::  File: krb5-install.info, Node: Client Programs, Next: Client Machine Configuration Files, Prev: Installing and Configuring UNIX Client Machines, Up: Installing and Configuring UNIX Client Machines Client Programs --------------- The Kerberized client programs are `login.krb5', `rlogin', `telnet', `ftp', `rcp', `rsh', `kinit', `klist', `kdestroy', `kpasswd', `ksu', and `krb524init'. All of these programs are in the directory `/usr/krb5/bin', except for `login.krb5' which is in `/usr/krb5/sbin'. You will probably want to have your users put `/usr/krb5/bin' ahead of `/bin' and `/usr/bin' in their paths, so they will by default get the Kerberos V5 versions of `rlogin', `telnet', `ftp', `rcp', and `rsh'. MIT recommends that you use `login.krb5' in place of `/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 `kinit', `klist', `kdestroy', and to use the Kerberos programs `ksu', and `kpasswd' in place of their non-Kerberos counterparts `su', `passwd', and `rdist'.  File: krb5-install.info, Node: Client Machine Configuration Files, Prev: Client Programs, Up: Installing and Configuring UNIX Client Machines Client Machine Configuration Files ---------------------------------- Each machine running Kerberos must have a `/etc/krb5.conf' file. (*Note krb5.conf::) Also, you must add the appropriate Kerberos services to each client machine's `/etc/services' file. If you are using the default configuration for Kerberos V5, you should be able to just insert the following code: # # 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 eklogin 2105/tcp # Kerberos auth. & encrypted rlogin krb524 4444/tcp # Kerberos 5 to 4 ticket translator 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 `kerberos' to 750 and create a `kerberos-sec' service (tcp and udp) on port 88, so the Kerberos V4 KDC(s) will continue to work properly.  File: krb5-install.info, Node: UNIX Application Servers, Prev: Installing and Configuring UNIX Client Machines, Up: Installing Kerberos V5 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 Kerberos V5 installed on all of your client machines, MIT 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 Kerberos V5 installed, you can run an insecure server, and still take advantage of Kerberos V5's single sign-on on capability. * Menu: * Server Programs:: * Server Configuration Files:: * The Keytab File:: * Some Advice about Secure Hosts::  File: krb5-install.info, Node: Server Programs, Next: Server Configuration Files, Prev: UNIX Application Servers, Up: UNIX Application Servers Server Programs --------------- Just as Kerberos V5 provided its own Kerberos-enhanced versions of client UNIX network programs, Kerberos V5 also provides Kerberos-enhanced versions of server UNIX network daemons. These are `ftpd', `klogind', `kshd', and `telnetd'. These programs are installed in the directory `/usr/krb5/sbin'. You may want to add this directory to root's path.  File: krb5-install.info, Node: Server Configuration Files, Next: The Keytab File, Prev: Server Programs, Up: UNIX Application Servers Server Configuration Files -------------------------- For a *secure* server, make the following changes to `/etc/inetd.conf': Find and comment out any lines for the services `ftp', `telnet', `shell', `login', and `exec'. Add the following lines. (Note: each line beginning with => is a continuation of the previous line.) klogin stream tcp nowait root /usr/krb5/sbin/klogind => klogind -k -c eklogin stream tcp nowait root /usr/krb5/sbin/klogind => klogind -k -c -e kshell stream tcp nowait root /usr/krb5/sbin/kshd => kshd -k -c -A ftp stream tcp nowait root /usr/krb5/sbin/ftpd => ftpd -a telnet stream tcp nowait root /usr/krb5/sbin/telnetd => telnetd -a valid For an *insecure* server, make the following changes instead to `/etc/inetd.conf': Find and comment out any lines for the services `ftp' and `telnet'. Add the following lines. (Note: each line beginning with => is a continuation of the previous line.) klogin stream tcp nowait root /usr/krb5/sbin/klogind => klogind -k -c eklogin stream tcp nowait root /usr/krb5/sbin/klogind => klogind -k -c -e kshell stream tcp nowait root /usr/krb5/sbin/kshd => kshd -k -c -A ftp stream tcp nowait root /usr/krb5/sbin/ftpd => ftpd telnet stream tcp nowait root /usr/krb5/sbin/telnetd => telnetd -a none  File: krb5-install.info, Node: The Keytab File, Next: Some Advice about Secure Hosts, Prev: Server Configuration Files, Up: UNIX Application Servers The Keytab File --------------- All Kerberos server machines need a "keytab" file, called `/etc/v5srvtab',(1) 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 (*Note 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 `Kerberos V5 System Administrator's Guide'. *Note Create Host Keys for the Slave KDCs:: for a brief description.) The keytab is generated by running `kadmin' and issuing the `ktadd' command. For example, to generate a keytab file to allow the host trillium.mit.edu to authenticate for the services `host', `ftp', and `pop', the administrator `joeadmin' would issue the command (on trillium.mit.edu): trillium% /usr/krb5/sbin/kadmin kadmin5: ktadd host/trillium.mit.edu ftp/trillium.mit.edu => pop/trillium.mit.edu kadmin: Entry for principal host/trillium.mit.edu@ATHENA.MIT.EDU with kvno 3, encryption type DES-CBC-CRC added to keytab WRFILE:/etc/v5srvtab. kadmin: Entry for principal ftp/trillium.mit.edu@ATHENA.MIT.EDU with kvno 3, encryption type DES-CBC-CRC added to keytab WRFILE:/etc/v5srvtab. kadmin: Entry for principal pop/trillium.mit.edu@ATHENA.MIT.EDU with kvno 3, encryption type DES-CBC-CRC added to keytab WRFILE:/etc/v5srvtab. kadmin5: quit trillium% If you generate the keytab file on another host, you need to get a copy of the keytab file onto the destination host (`trillium', in the above example) without sending it unencrypted over the network. If you have installed the Kerberos V5 client programs, you can use encrypted `rcp'. ---------- Footnotes ---------- (1) The keytab was called a "srvtab" in Kerberos V4. The `v5srvtab' file has not been renamed to reflect the change in terminology.  File: krb5-install.info, Node: Some Advice about Secure Hosts, Prev: The Keytab File, Up: UNIX Application Servers Some Advice about Secure Hosts ------------------------------ Kerberos V5 can protect your host from certain types of break-ins, but it is possible to install Kerberos V5 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, MIT recommends that on a secure host, you disable the standard `ftp', `login', `telnet', `shell', and `exec' services in `/etc/services'. We also recommend that secure hosts have an empty `/etc/hosts.equiv' file and that there not be a `.rhosts' file in `root''s home directory. You can grant Kerberos-authenticated root access to specific Kerberos principals by placing those principals in the file `.k5login' in root's home directory. We recommend that backups of secure machines exclude the keytab file (`/etc/v5srvtab'). 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 Kerberos V5 binaries, should be kept on local disk. The keytab file should be readable only by root.  File: krb5-install.info, Node: Bug Reports for Kerberos V5, Next: Files, Prev: Installing Kerberos V5, Up: Top Bug Reports for Kerberos V5 *************************** In any complex software, there will be bugs. Please send bug reports or other problems you may uncover to the e-mail address krb5-bugs@mit.edu. Please mention which version of the Kerberos V5 distribution you are using, and whether you have made any private changes. Bug reports that include proposed fixes are especially welcome. If you do include fixes, please send them using either context diffs or unified diffs (using `diff -c' or `diff -u', respectively).  File: krb5-install.info, Node: Files, Prev: Bug Reports for Kerberos V5, Up: Top Files ***** * Menu: * krb5.conf:: * kdc.conf::  File: krb5-install.info, Node: krb5.conf, Next: kdc.conf, Prev: Files, Up: Files krb5.conf ========= Here is an example of a generic `krb5.conf' file: [libdefaults] ticket_lifetime = 600 default_realm = ATHENA.MIT.EDU default_tkt_enctypes = des-cbc-crc default_tgs_enctypes = des-cbc-crc [realms] ATHENA.MIT.EDU = { kdc = kerberos.mit.edu:88 kdc = kerberos-1.mit.edu:88 kdc = kerberos-2.mit.edu:88 admin_server = kerberos.mit.edu:749 default_domain = mit.edu } } [domain_realm] .mit.edu = ATHENA.MIT.EDU mit.edu = ATHENA.MIT.EDU For the KDCs, add a section onto the end of the `krb5.conf' file telling where the `kdc.conf' file is located, as in the following example: [kdc] profile = /usr/krb5/lib/krb5kdc/kdc.conf [logging] kdc = FILE:/dev/ttyp9 admin_server = FILE:/dev/ttyp9 default = FILE:/dev/ttyp9  File: krb5-install.info, Node: kdc.conf, Prev: krb5.conf, Up: Files kdc.conf ======== Here's an example of a generic kdc.conf file: [kdcdefaults] kdc_ports = 88,750 [realms] ATHENA.MIT.EDU = { profile = /etc/krb5.conf database_name = /usr/krb5/lib/krb5kdc/principal admin_database_name = /usr/krb5/lib/krb5kdc/principal.kadm5 admin_database_lockfile = /usr/krb5/lib/krb5kdc/principal.kadm5.lock admin_keytab = /usr/krb5/lib/krb5kdc/kadm5.keytab acl_file = /usr/krb5/lib/krb5kdc/kadm5.acl dict_file = /usr/krb5/lib/krb5kdc/kadm5.dict key_stash_file = /usr/krb5/lib/krb5kdc/.k5.ATHENA.MIT.EDU kadmind_port = 749 max_life = 10h 0m 0s max_renewable_life = 7d 0h 0m 0s master_key_type = des-cbc-crc supported_enctypes = des-cbc-crc:normal } To add Kerberos V4 support, change the `supported_enctypes' line to: supported_enctypes = des-cbc-crc:normal des-cbc-crc:v4 * Menu: * Encryption Types and Salt Types::  File: krb5-install.info, Node: Encryption Types and Salt Types, Prev: kdc.conf, Up: kdc.conf Encryption Types and Salt Types ------------------------------- Currently, Kerberos V5 supports only DES encryption. The encoding type is `des-cbc-crc'. The "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: * "normal", which MIT recommends using for all of your Kerberos V5 keys * "v4", which is necessary only for compatibility with a v4 KDC * "afs", which you will never need to generate, and which you will encounter only if you dump an AFS database into a Kerberos database Support for additional encryption types is planned in the future.