This is Info file krb5-admin.info, produced by Makeinfo-1.55 from the input file admin.texinfo.  File: krb5-admin.info, Node: Privileges, Next: Adding or Modifying Principals, Prev: Retrieving Information About a Principal, Up: Principals Privileges ---------- Administrative privileges for the Kerberos database are stored in the file `kadm5.acl'. Each line of the file contains a principal, the privileges that principal has, and optionally the target to which those permissions apply. The privileges are represented by single letters; UPPER-CASE letters represent negative permissions. The permissions are: a allows the addition of principals or policies in the database. A disallows the addition of principals or policies in the database. d allows the deletion of principals or policies in the database. D disallows the deletion of principals or policies in the database. m allows the modification of principals or policies in the database. M disallows the modification of principals or policies in the database. c allows the changing of passwords for principals in the database. C disallows the changing of passwords for principals in the database. i allows inquiries to the database. I disallows inquiries to the database. l allows the listing of principals or policies in the database. L disallows the listing of principals or policies in the database. * All privileges (admcil). x All privileges (admcil); identical to "*". Principals in this file can include the * wildcard. Here is an example of a `kadm5.acl' file. Note that order is important; permissions are determined by the first matching entry. */admin@ATHENA.MIT.EDU * joeadmin@ATHENA.MIT.EDU ADMCIL joeadmin/*@ATHENA.MIT.EDU il jennifer/root@ATHENA.MIT.EDU cil */root@ATHENA.MIT.EDU */*@ATHENA.MIT.EDU i In the above file, any principal with an `admin' instance has all administrative privileges. The user `joeadmin' has all permissions with his `admin' instance, `joeadmin/admin@ATHENA.MIT.EDU' (matches the first line). He has no permissions at all with his `null' instance, `joeadmin@ATHENA.MIT.EDU' (matches the second line). He has inquire and list permissions with any other instance (matches the third line). When `jennifer' is using her `root' instance, `jennifer/root@ATHENA.MIT.EDU', she has change password, inquire, and list privileges for any other principal that has the instance `root'. Finally, any principal in the realm `ATHENA.MIT.EDU' (except for `joeadmin@ATHENA.MIT.EDU', as mentioned above) has inquire privileges.  File: krb5-admin.info, Node: Adding or Modifying Principals, Next: Deleting Principals, Prev: Privileges, Up: Principals Adding or Modifying Principals ------------------------------ To add a principal to the database, use the kadmin `add_principal' command, which requires the "add" administrative privilege. This function creates the new principal and, if neither the -policy nor -clearpolicy options are specified and the policy "default" exists, assigns it that policy. The syntax is: kadmin: add_principal [options] principal To modify attributes of a principal, use the kadmin `modify_principal' command, which requires the "modify" administrative privilege. The syntax is: kadmin: modify_principal [options] principal `add_principal' has the aliases `addprinc' and `ank'(1). `modify_principal' has the alias `modprinc'. The `add_principal' and `modify_principal' commands take the following switches: -salt salttype Uses the specified salt for generating the key. The valid salt types are: * full_name (aliases "v5_salt" and "normal"; this is the default) * name_only * realm_only * no_salt (alias "v4_salt") -clearpolicy For `modify_principal', removes the current policy from a principal. For `add_principal', suppresses the automatic assignment of the policy "default". -expire date Sets the expiration date of the principal to date. -pwexpire date Sets the expiration date of the password to date. -maxlife maxlife Sets the maximum ticket life of the principal to maxlife. -kvno number Explicity sets the key version number to number. MIT does not recommend doing this unless there is a specific reason. -policy policy Sets the policy used by this principal. (*Note Policies::.) With `modify_principal', the current policy assigned to the principal is set or changed. With `add_principal', if this option is not supplied, the -clearpolicy is not specified, and the policy "default" exists, that policy is assigned. If a principal is created with no policy, `kadmin' will print a warning message. {-|+}allow_postdated The "-allow_postdated" option prohibits this principal from obtaining postdated tickets. "+allow_postdated" clears this flag. In effect, "-allow_postdated" sets the KRB5_KDB_DISALLOW_POSTDATED flag on the principal in the database. {-|+}allow_forwardable The "-allow_forwardable" option prohibits this principal from obtaining forwardable tickets. "+allow_forwardable" clears this flag. In effect, "-allow_forwardable" sets the KRB5_KDB_DISALLOW_FORWARDABLE flag on the principal in the database. {-|+}allow_renewable The "-allow_renewable" option prohibits this principal from obtaining renewable tickets. "+allow_renewable" clears this flag. In effect, "-allow_renewable" sets the KRB5_KDB_DISALLOW_RENEWABLE flag on the principal in the database. {-|+}allow_proxiable The "-allow_proxiable" option prohibits this principal from obtaining proxiable tickets. "+allow_proxiable" clears this flag. In effect, "-allow_proxiable" sets the KRB5_KDB_DISALLOW_PROXIABLE flag. on the principal in the database. {-|+}allow_dup_skey The "-allow_dup_skey" option disables user-to-user authentication for this principal by prohibiting this principal from obtaining a session key for another user. "+allow_dup_skey" clears this flag. In effect, "-allow_dup_skey" sets the KRB5_KDB_DISALLOW_DUP_SKEY flag on the principal in the database. {-|+}requires_preauth The "+requires_preauth" option requires this principal to preauthenticate before being allowed to kinit. -requires_preauth clears this flag. In effect, +requires_preauth sets the KRB5_KDB_REQUIRES_PRE_AUTH flag on the principal in the database. {-|+}requires_hwauth The "+requires_hwauth" flag requires the principal to preauthenticate using a hardware device before being allowed to kinit. "-requires_hwauth" clears this flag. In effect, "+requires_hwauth" sets the KRB5_KDB_REQUIRES_HW_AUTH flag on the principal in the database. {-|+}allow_svr The "-allow_svr" flag prohibits the issuance of service tickets for this principal. "+allow_svr" clears this flag. In effect, "-allow_svr" sets the KRB5_KDB_DISALLOW_SVR flag on the principal in the database. {-|+}allow_tgs_req The "-allow_tgs_req" option specifies that a Ticket-Granting Service (TGS) request for a service ticket for this principal is not permitted. You will probably never need to use this option. "+allow_tgs_req" clears this flag. The default is "+allow_tgs_req". In effect, "-allow_tgs_req" sets the KRB5_KDB_DISALLOW_TGT_BASED flag on the principal in the database. {-|+}allow_tix The "-allow_tix" option forbids the issuance of any tickets for this principal. "+allow_tix" clears this flag. The default is "+allow_tix". In effect, "-allow_tix" sets the KRB5_KDB_DISALLOW_ALL_TIX flag on the principal in the database. {-|+}needchange The "+needchange" option sets a flag in attributes field to force a password change; "-needchange" clears it. The default is "-needchange". In effect, "+needchange" sets the KRB5_KDB_REQUIRES_PWCHANGE flag on the principal in the database. {-|+}password_changing_service The "+password_changing_service" option sets a flag in the attributes field marking this principal as a password change service. (Again, you will probably never need to use this option.) "-password_changing_service" clears the flag. The default is "-password_changing_service". In effect, the "+password_changing_service" option sets the KRB5_KDB_PWCHANGE_SERVICE flag on the principal in the database. -clearpolicy policyname Removes the policy policyname from the principal (`modify_principal' only). -randkey Sets the key for the principal to a random value (`add_principal' only). MIT recommends using this option for host keys. -pw password Sets the key of the principal to the specified string and does not prompt for a password (`add_principal' only). MIT does not recommend using this option. If you want to just use the default values, all you need to do is: kadmin: addprinc jennifer WARNING: no policy specified for "jennifer@ATHENA.MIT.EDU"; defaulting to no policy. Enter password for principal jennifer@ATHENA.MIT.EDU: <= Type the password. Re-enter password for principal jennifer@ATHENA.MIT.EDU: <=Type it again. Principal "jennifer@ATHENA.MIT.EDU" created. kadmin: If, on the other hand, you want to set up an account that expires on January 1, 2000, that uses a policy called "stduser", with a temporary password (which you want the user to change immediately), you would type the following. (Note: each line beginning with => is a continuation of the previous line.) kadmin: addprinc david -expire "1/1/2000 12:01am EST" -policy stduser => +needchange Enter password for principal david@ATHENA.MIT.EDU: <= Type the password. Re-enter password for principal david@ATHENA.MIT.EDU: <= Type it again. Principal "david@ATHENA.MIT.EDU" created. kadmin: If you will need cross-realm authentication, you need to add principals for the other realm's TGT to each realm. For example, if you need to do cross-realm authentication between the realms ATHENA.MIT.EDU and FUBAR.ORG, you would need to add the principals `krbtgt/FUBAR.ORG@ATHENA.MIT.EDU' and `krbtgt/ATHENA.MIT.EDU@FUBAR.ORG' to both databases. You need to be sure the passwords and the key version numbers (kvno) are the same in both databases. This may require explicitly setting the kvno with the `-kvno' option. ---------- Footnotes ---------- (1) `ank' was the short form of the equivalent command using the deprecated `kadmin5' database administrative tool. It has been kept  File: krb5-admin.info, Node: Deleting Principals, Next: Changing Passwords, Prev: Adding or Modifying Principals, Up: Principals Deleting Principals ------------------- To delete a principal, use the kadmin `delete_principal' command, which requires the "delete" administrative privilege. The syntax is: delete_principal [-force] principal `delete_principal' has the alias `delprinc'. The `-force' option causes `delete_principal' not to ask if you're sure. For example: kadmin: delprinc jennifer Are you sure you want to delete the principal "jennifer@ATHENA.MIT.EDU"? (yes/no): yes Principal "jennifer@ATHENA.MIT.EDU" deleted. Make sure that you have removed this principal from all ACLs before reusing. kadmin:  File: krb5-admin.info, Node: Changing Passwords, Next: Renaming Principals, Prev: Deleting Principals, Up: Principals Changing Passwords ------------------ To change a principal's password use the kadmin `change_password' command, which requires the "modify" administrative privilege (unless the principal is changing his/her own password). The syntax is: change_password [options] principal The `change_password' option has the alias `cpw'. `change_password' takes the following options: -salt salttype Uses the specified salt for generating the key. Salt types are the same as for the `add_principal' command (*note Adding or Modifying Principals::.). -randkey Sets the key of the principal to a random value. -pw password Sets the password to the string password. MIT does not recommend using this option. For example: kadmin: cpw david Enter password for principal david@ATHENA.MIT.EDU: <= Type the new password. Re-enter password for principal david@ATHENA.MIT.EDU: <= Type it again. Password for david@ATHENA.MIT.EDU changed. kadmin: Note that `change_password' will not let you change the password to one that is in the principal's password history.  File: krb5-admin.info, Node: Renaming Principals, Prev: Changing Passwords, Up: Principals Renaming Principals ------------------- To rename a principal, use the kadmin `rename_principal' command, which requires both the "add" and "delete" administrative privileges. The syntax is: rename_principal [-force] old_principal new_principal The `rename_principal' command has the alias `renprinc'. For example: kadmin: renprinc test test0 Are you sure you want to rename the principal "test@ATHENA.MIT.EDU" to "test0@ATHENA.MIT.EDU"? (yes/no): yes Principal "test@ATHENA.MIT.EDU" renamed to "test0@ATHENA.MIT.EDU". Make sure that you have removed "test@ATHENA.MIT.EDU" from all ACLs before reusing. kadmin:  File: krb5-admin.info, Node: Policies, Next: Dumping a Kerberos Database to a File, Prev: Principals, Up: Administrating Kerberos Database Entries Policies ======== A policy is a set of rules governing passwords. Policies can dictate minimum and maximum password lifetimes, minimum number of characters and character classes a password must contain, and the number of old passwords kept in the database. * Menu: * Retrieving Policies:: * Retrieving the List of Policies:: * Adding or Modifying Policies:: * Deleting Policies::  File: krb5-admin.info, Node: Retrieving Policies, Next: Retrieving the List of Policies, Prev: Policies, Up: Policies Retrieving Policies ------------------- To retrieve a policy, use the kadmin `get_policy' command, which requires the "inquire" administrative privilege. The syntax is: get_policy [-terse] policy The `get_policy' command has the alias `getpol'. For example: kadmin: get_policy admin Policy: admin Maximum password life: 180 days 00:00:00 Minimum password life: 00:00:00 Minimum password length: 6 Minimum number of password character classes: 2 Number of old keys kept: 5 Reference count: 17 kadmin: The "reference count" is the number of principals using that policy. The `get_policy' command has a `-terse' option, which lists each field as a quoted, tab-separated string. For example: kadmin: get_policy -terse admin admin 15552000 0 6 2 5 17 kadmin:  File: krb5-admin.info, Node: Retrieving the List of Policies, Next: Adding or Modifying Policies, Prev: Retrieving Policies, Up: Policies Retrieving the List of Policies ------------------------------- You can retrieve the list of policies with the kadmin `list_policies' command, which requires the "list" privilege. The syntax is: list_policies [expression] where expression is a shell-style glob expression that can contain the characters *, ?, and []. All policy names matching the expression are displayed. The `list_policies' command has the alias `listpols'. For example: kadmin: listpols test-pol dict-only once-a-min test-pol-nopw kadmin: listpols t* test-pol test-pol-nopw kadmin:  File: krb5-admin.info, Node: Adding or Modifying Policies, Next: Deleting Policies, Prev: Retrieving the List of Policies, Up: Policies Adding or Modifying Policies ---------------------------- To add a new policy, use the kadmin `add_policy' command, which requires the "add" administrative privilege. The syntax is: add_policy [options] policy_name To modify attributes of a principal, use the kadmin `modify_policy' command, which requires the "modify" administrative privilege. The syntax is: modify_policy [options] policy_name `add_policy' has the alias `addpol'. `modify_poilcy' has the alias `modpol'. The `add_policy' and `modify_policy' commands take the following switches: -maxlife time Sets the maximum lifetime of a password to time. -minlife time Sets the minimum lifetime of a password to time. -minlength length Sets the minimum length of a password to length characters. -minclasses number Requires at least number of character classes in a password. -history number Sets the number of past keys kept for a principal to number.  File: krb5-admin.info, Node: Deleting Policies, Prev: Adding or Modifying Policies, Up: Policies Deleting Policies ----------------- To delete a policy, use the `kadmin' `delete_policy' command, which requires the "delete" administrative privilege. The syntax is: delete_policy policy_name The `delete_policy' command has the alias `delpol'. It prompts for confirmation before deletion. For example: kadmin: delete_policy guests Are you sure you want to delete the policy "guests"? (yes/no): yes Policy "guests" deleted. kadmin: Note that you must cancel the policy from all principals before deleting it. The `delete_policy' command will fail if it is in use by any principals.  File: krb5-admin.info, Node: Dumping a Kerberos Database to a File, Next: Restoring a Kerberos Database from a Dump File, Prev: Policies, Up: Administrating Kerberos Database Entries Dumping a Kerberos Database to a File ===================================== To dump a Kerberos database into a file, use the `kdb5_util' `dump' command on one of the KDCs. The syntax is: kdb5_util dump [-old] [-b6] [-ov] [-verbose] [filename [principals...]] The `kdb5_util dump' command takes the following options: -old causes the dump to be in the Kerberos 5 Beta 5 and earlier dump format ("kdb5_edit load_dump version 2.0"). -b6 causes the dump to be in the Kerberos 5 Beta 6 format ("kdb5_edit load_dump version 3.0"). -ov causes the dump to be in ovsec_adm_export format. -verbose causes the name of each principal and policy to be printed as it is dumped. For example: shell% kdb5_util dump dumpfile shell% shell% kbd5_util dump -verbose dumpfile kadmin/admin@ATHENA.MIT.EDU krbtgt/ATHENA.MIT.EDU@ATHENA.MIT.EDU kadmin/history@ATHENA.MIT.EDU K/M@ATHENA.MIT.EDU kadmin/changepw@ATHENA.MIT.EDU shell% If you specify which principals to dump, you must use the full principal, as in the following example. (The line beginning with => is a continuation of the previous line.): shell% kdb5_util dump -verbose dumpfile K/M@ATHENA.MIT.EDU => kadmin/admin@ATHENA.MIT.EDU kadmin/admin@ATHENA.MIT.EDU K/M@ATHENA.MIT.EDU shell% Otherwise, the principals will not match those in the database and will not be dumped: shell% kdb5_util dump -verbose dumpfile K/M kadmin/admin shell% If you do not specify a dump file, `kdb5_util' will dump the database to the standard output.  File: krb5-admin.info, Node: Restoring a Kerberos Database from a Dump File, Next: Creating a Stash File, Prev: Dumping a Kerberos Database to a File, Up: Administrating Kerberos Database Entries Restoring a Kerberos Database from a Dump File ============================================== To restore a Kerberos database dump from a file, use the `kdb5_util' `load' command on one of the KDCs. The syntax is: kdb5_util load [-old] [-b6] [-ov] [-verbose] [-update] dumpfilename dbname [admin_dbname] The `kdb5_util load' command takes the following options: -old requires the dump to be in the Kerberos 5 Beta 5 and earlier dump format ("kdb5_edit load_dump version 2.0"). -b6 requires the dump to be in the Kerberos 5 Beta 6 format ("kdb5_edit load_dump version 3.0"). -ov requires the dump to be in ovsec_adm_export format. -verbose causes the name of each principal and policy to be printed as it is dumped. -update causes records from the dump file to be updated in or added to the existing database. For example: shell% kdb5_util load dumpfile principal shell% shell% kdb5_util load -update dumpfile principal shell% If the database file exists, and the -update flag was not given, `kdb5_util' will overwrite the existing database.  File: krb5-admin.info, Node: Creating a Stash File, Next: Creating and Destroying a Kerberos Database, Prev: Restoring a Kerberos Database from a Dump File, Up: Administrating Kerberos Database Entries Creating a Stash File ===================== A stash file allows a KDC to authenticate itself to the database utilities, such as `kadmin', `kadmind', `krb5kdc', and `kdb5_util'. To create a stash file, use the `kdb5_util' `stash' command. The syntax is: kdb5_util stash [-f keyfile] For example: 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: <= Type the KDC database master password. shell% If you do not specify a stash file, `kdb5_util' will stash the key in the file specified in your `kdc.conf' file.  File: krb5-admin.info, Node: Creating and Destroying a Kerberos Database, Prev: Creating a Stash File, Up: Administrating Kerberos Database Entries Creating and Destroying a Kerberos Database =========================================== If you need to create a new Kerberos database, use the `kdb5_util' `create' command. The syntax is: kdb5_util create [-s] If you specify the `-s' option, `kdb5_util' will stash a copy of the master key in a stash file. (*Note Creating a Stash File::.) For example: shell% /usr/local/sbin/kdb5_util -r ATHENA.MIT.EDU create -s kdb5_util: No such file or directory while setting active database to => '/usr/local/var/krb5kdc/principal' Initializing database '/usr/local/var/krb5kdc/principal' for => realm 'ATHENA.MIT.EDU', master key name 'K/M@ATHENA.MIT.EDU' You will be prompted for the database Master Password. It is important that you NOT FORGET this password. Enter KDC database master key: <= Type the master password. Re-enter KDC database master key to verify: <= Type it again. shell%  File: krb5-admin.info, Node: Application Servers, Next: Backups of Secure Hosts, Prev: Administrating Kerberos Database Entries, Up: Top Application Servers ******************* If you need to install the Kerberos V5 programs on an application server, please refer to the Kerberos V5 Installation Guide. Once you have installed the software, you need to add that host to the Kerberos database (*note Adding or Modifying Principals::.), and generate a "keytab" for that host, that contains the host's key. You also need to make sure the host's clock is within your maximum clock skew of the KDCs. * Menu: * Keytabs:: * Clock Skew:: * Getting DNS Information Correct:: * Configuring Your Firewall to Work With Kerberos V5::  File: krb5-admin.info, Node: Keytabs, Next: Clock Skew, Prev: Application Servers, Up: Application Servers Keytabs ======= A "keytab" is a host's copy of its own keylist, which is analogous to a user's password. An application server that needs to authenticate itself to the KDC has to have a keytab that contains its own principal and key. Just as it is important for users to protect their passwords, it is equally important for hosts to protect their keytabs. You should always store keytab files on local disk, and make them readable only by root, and you should never send a keytab file over a network in the clear. Ideally, you should run the `kadmin' command to extract a keytab on the host on which the keytab is to reside. * Menu: * Adding Principals to Keytabs:: * Removing Principals from Keytabs::  File: krb5-admin.info, Node: Adding Principals to Keytabs, Next: Removing Principals from Keytabs, Prev: Keytabs, Up: Keytabs Adding Principals to Keytabs ---------------------------- To generate a keytab, or to add a principal to an existing keytab, use the `ktadd' command from `kadmin', which requires the "inquire" administrative privilege. (If you use the -glob princ_exp option, it also requires the "list" administrative privilege.) The syntax is: ktadd [-k keytab] [-q] [principal | -glob princ_exp] [...] The `ktadd' command takes the following switches: -k keytab use keytab as the keytab file. Otherwise, `ktadd' will use the default keytab file (`/etc/krb5.keytab'). -q run in quiet mode. This causes `ktadd' to display less verbose information. principal | -glob principal expression add principal, or all principals matching principal expression to the keytab. The rules for principal expression are the same as for the kadmin `list_principals' (*note Retrieving a List of Principals::.) command. For example (The line beginning with => is a continuation of the previous line.): kadmin: ktadd host/daffodil.mit.edu@ATHENA.MIT.EDU kadmin: Entry for principal host/daffodil.mit.edu@ATHENA.MIT.EDU with kvno 2, encryption type DES-CBC-CRC added to keytab WRFILE:/etc/krb5.keytab. kadmin: kadmin: ktadd -k /usr/local/var/krb5kdc/kadmind.keytab => kadmin/admin kadmin/changepw kadmin: Entry for principal kadmin/admin@ATHENA.MIT.EDU with kvno 3, encryption type DES-CBC-CRC added to keytab WRFILE:/usr/local/var/krb5kdc/kadmind.keytab. kadmin:  File: krb5-admin.info, Node: Removing Principals from Keytabs, Prev: Adding Principals to Keytabs, Up: Keytabs Removing Principals from Keytabs -------------------------------- To remove a principal to an existing keytab, use the kadmin `ktremove' command. The syntax is: ktremove [-k keytab] [-q] principal [kvno | all | old] The `ktremove' command takes the following switches: -k keytab use keytab as the keytab file. Otherwise, `ktremove' will use the default keytab file (`/etc/krb5.keytab'). -q run in quiet mode. This causes `ktremove' to display less verbose information. principal the principal to remove from the keytab. (Required.) kvno remove all entries for the specified principal whose Key Version Numbers match kvno. all remove all entries for the specified principal old remove all entries for the specified principal except those with the highest kvno. For example: kadmin: ktremove -k /usr/local/var/krb5kdc/kadmind.keytab kadmin/admin kadmin: Entry for principal kadmin/admin with kvno 3 removed from keytab WRFILE:/usr/local/var/krb5kdc/kadmind.keytab. kadmin:  File: krb5-admin.info, Node: Clock Skew, Next: Getting DNS Information Correct, Prev: Keytabs, Up: Application Servers Clock Skew ========== In order to prevent intruders from resetting their system clocks in order to continue to use expired tickets, Kerberos V5 is set up to reject ticket requests from any host whose clock is not within the specified maximum clock skew of the KDC (as specified in the `kdc.conf' file). Similarly, hosts are configured to reject responses from any KDC whose clock is not within the specified maximum clock skew of the host (as specified in the `krb5.conf' file). The default value for maximum clock skew is 300 seconds (five minutes). MIT suggests that you add a line to client machines' `/etc/rc' files to synchronize the machine's clock to your KDC at boot time. On UNIX hosts, assuming you had a kdc called `kerberos' in your realm, this would be: gettime -s kerberos If the host is not likely to be rebooted frequently, you may also want to set up a cron job that adjusts the time on a regular basis.  File: krb5-admin.info, Node: Getting DNS Information Correct, Next: Configuring Your Firewall to Work With Kerberos V5, Prev: Clock Skew, Up: Application Servers Getting DNS Information Correct =============================== Several aspects of Kerberos rely on name service. In order for Kerberos to provide its high level of security, it is less forgiving of name service problems than some other parts of your network. It is important that your Domain Name System (DNS) entries and your hosts have the correct information. Each host's canonical name must be the fully-qualified host name (including the domain), and each host's IP address must reverse-resolve to the canonical name. Other than the `localhost' entry, make all entries in each machine's `/etc/hosts' file in the following form: IP address fully-qualified hostname aliases Here is a sample `/etc/hosts' file: # this is a comment 127.0.0.1 localhost localhost@mit.edu 10.0.0.6 daffodil.mit.edu trillium wake-robin Additionally, on Solaris machines, you need to be sure the "hosts" entry in the file `/etc/nsswitch.conf' includes the source "dns" as well as "file". Finally, each host's keytab file must include a host/key pair for the host's canonical name. You can list the keys in a keytab file by issuing the command `klist -k'. For example: viola# klist -k Keytab name: /etc/krb5.keytab KVNO Principal ---- ------------------------------------------------------------ 1 host/daffodil.mit.edu@ATHENA.MIT.EDU If you telnet to the host with a fresh credentials cache (ticket file), and then `klist', the host's service principal should be host/fully-qualified-hostname@REALM_NAME.  File: krb5-admin.info, Node: Configuring Your Firewall to Work With Kerberos V5, Prev: Getting DNS Information Correct, Up: Application Servers Configuring Your Firewall to Work With Kerberos V5 ================================================== If you need off-site users to be able to get Kerberos tickets in your realm, they must be able to get to your KDC. This requires either that you have a slave KDC outside your firewall, or you configure your firewall to allow UDP requests into to at least one of your KDCs, on whichever port the KDC is running. (The default is port 88; other ports may be specified in the KDC's kdc.conf file.) Similarly, if you need off-site users to be able to change their passwords in your realm, they must be able to get to your Kerberos admin server. The default port for the admin server is 749. If your on-site users inside your firewall will need to get to KDCs in other realms, you will also need to configure your firewall to allow outgoing TCP and UDP requests to port 88. Additionally, if they will need to get to any Kerberos V4 KDCs, you may also need to allow TCP and UDP requests to port 750. If your on-site users inside your firewall will need to get to Kerberos admin servers in other realms, you will also need to allow outgoing TCP and UDP requests to port 749. If any of your KDCs is outside your firewall, you will need to allow `kprop' requests to get through to the remote KDC. `Kprop' uses the krb5_prop service on port 754 (tcp). If you need your off-site users to have access to machines inside your firewall, you need to allow TCP connections from their off-site hosts on the appropriate ports for the programs they will be using. The following lines from `/etc/services' show the default port numbers for the Kerberos V5 programs: ftp 21/tcp # Kerberos ftp and telnet use the telnet 23/tcp # default ports 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 By default, Kerberos V5 `telnet' and `ftp' use the same ports as the standard `telnet' and `ftp' programs, so if you already allow telnet and ftp connections through your firewall, the Kerberos V5 versions will get through as well. If you do not already allow telnet and ftp connections through your firewall, but need your users to be able to use Kerberos V5 telnet and ftp, you can either allow ftp and telnet connections on the standard ports, or switch these programs to non-default port numbers and allow ftp and telnet connections on those ports to get through. Kerberos V5 `rlogin' uses the `klogin' service, which by default uses port 543. Encrypted Kerberos V5 rlogin uses uses the `eklogin' service, which by default uses port 2105. Kerberos V5 `rsh' uses the `kshell' service, which by default uses port 544. However, the server must be able to make a TCP connection from the kshell port to an arbitrary port on the client, so if your users are to be able to use `rsh' from outside your firewall, the server they connect to must be able to send outgoing packets to arbitrary port numbers. Similarly, if your users need to run `rsh' from inside your firewall to hosts outside your firewall, the outside server needs to be able to connect to an arbitrary port on the machine inside your firewall. Because Kerberos V5 `rcp' uses `rsh', the same issues apply. If you need to use `rsh' (or `rcp') through your firewall and are concerned with the security implications of allowing connections to arbitrary ports, MIT suggests that you have rules that specifically name these applications and, if possible, list the allowed hosts. A reasonably good cookbook for configuring firewalls is available by FTP from `ftp.livingston.com', in the location: `/pub/firewall/firewall-1.1.ps.Z'. The book `UNIX System Security', by David Curry, is also a good starting point.  File: krb5-admin.info, Node: Backups of Secure Hosts, Next: Bug Reporting, Prev: Application Servers, Up: Top Backups of Secure Hosts *********************** When you back up a secure host, you should exclude the host's keytab file from the backup. If someone obtained a copy of the keytab from a backup, that person could make any host masquerade as the host whose keytab was compromised. This could be particularly dangerous if the compromised keytab was from one of your KDCs. If the machine has a disk crash and the keytab file is lost, it is easy to generate another keytab file. (*Note Adding Principals to Keytabs::.) If you are unable to exclude particular files from backups, you should ensure that the backups are kept as secure as the host's root password. * Menu: * Backing Up the Kerberos Database::  File: krb5-admin.info, Node: Backing Up the Kerberos Database, Prev: Backups of Secure Hosts, Up: Backups of Secure Hosts Backing Up the Kerberos Database ================================ As with any file, it is possible that your Kerberos database could become corrupted. If this happens on one of the slave KDCs, you might never notice, since the next automatic propagation of the database would install a fresh copy. However, if it happens to the master KDC, the corrupted database would be propagated to all of the slaves during the next propagation. For this reason, MIT recommends that you back up your Kerberos database regularly. Because the master KDC is continuously dumping the database to a file in order to propagate it to the slave KDCs, it is a simple matter to have a cron job periodically copy the dump file to a secure machine elsewhere on your network. (Of course, it is important to make the host where these backups are stored as secure as your KDCs, and to encrypt its transmission across your network.) Then if your database becomes corrupted, you can load the most recent dump onto the master KDC. (*Note Restoring a Kerberos Database from a Dump File::.)  File: krb5-admin.info, Node: Bug Reporting, Next: Appendix, Prev: Backups of Secure Hosts, Up: Top Bug Reporting ************* In any complex software, there will be bugs. If you have successfully built and installed Kerberos V5, please use the `krb5-send-pr' program to fill out a Problem Report. 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). The `krb5-send-pr' program is installed in the directory `/usr/local/sbin'. The `krb5-send-pr' program enters the problem report into our Problem Report Management System (PRMS), which automatically assigns it to the engineer best able to help you with problems in the assigned category. The `krb5-send-pr' program will try to intelligently fill in as many fields as it can. You need to choose the "category", "class", "severity", and "priority" of the problem, as well as giving us as much information as you can about its exact nature. The PR category will be one of: krb5-admin krb5-appl krb5-build krb5-clients krb5-doc krb5-kdc krb5-libs krb5-misc pty telnet test Choose the category that best describes the area under which your problem falls. The class can be "sw-bug", "doc-bug", "change-request", or "support". The first two are exactly as their names imply. Use change-request when the software is behaving according to specifications, but you want to request changes in some feature or behavior. The support class is intended for more general questions about building or using Kerberos V5. The severity of the problem indicates the problem's impact on the usability of Kerberos V5. If a problem is "critical", that means the product, component or concept is completely non-operational, or some essential functionality is missing, and no workaround is known. A "serious" problem is one in which the product, component or concept is not working properly or significant functionality is missing. Problems that would otherwise be considered critical are rated serious when a workaround is known. A "non-critical" problem is one that is indeed a problem, but one that is having a minimal effect on your ability to use Kerberos V5. E.g., The product, component or concept is working in general, but lacks features, has irritating behavior, does something wrong, or doesn't match its documentation. The default severity is serious. The priority indicates how urgent this particular problem is in relation to your work. Note that low priority does not imply low importance. A priority of "high" means a solution is needed as soon as possible. A priority of "medium" means the problem should be solved no later than the next release. A priority of "low" means the problem should be solved in a future release, but it is not important to your work how soon this happens. The default priority is medium. Note that a given severity does not necessarily imply a given priority. For example, a non-critical problem might still have a high priority if you are faced with a hard deadline. Conversely, a serious problem might have a low priority if the feature it is disabling is one that you do not need. It is important that you fill in the release field and tell us what changes you have made, if any. Bug reports that include proposed fixes are especially welcome. If you include proposed fixes, please send them using either context diffs (`diff -c') or unified diffs (`diff -u'). A sample filled-out form from a company named "Toasters, Inc." might look like this: To: krb5-bugs@mit.edu Subject: misspelled "Kerberos" in title of installation guide From: jcb Reply-To: jcb Cc: X-send-pr-version: 3.99 >Submitter-Id: mit >Originator: Jeffrey C. Gilman Bigler >Organization: mit >Confidential: no >Synopsis: Misspelled "Kerberos" in title of installation guide >Severity: non-critical >Priority: low >Category: krb5-doc >Class: doc-bug >Release: 1.0-development >Environment: System: ULTRIX imbrium 4.2 0 RISC Machine: mips >Description: Misspelled "Kerberos" in title of "Kerboros V5 Installation Guide" >How-To-Repeat: N/A >Fix: Correct the spelling. If the `krb5-send-pr' program does not work for you, or if you did not get far enough in the process to have an installed and working `krb5-send-pr', you can generate your own form, using the above as an example.  File: krb5-admin.info, Node: Appendix, Prev: Bug Reporting, Up: Top Appendix ******** * Menu: * Errors:: * kadmin Time Zones::  File: krb5-admin.info, Node: Errors, Next: kadmin Time Zones, Prev: Appendix, Up: Appendix Kerberos Error Messages ======================= * Menu: * Kerberos V5 Library Error Codes:: * Kerberos V5 Database Library Error Codes:: * Kerberos V5 Magic Numbers Error Codes:: * ASN.1 Error Codes:: * GSSAPI Error Codes::