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kdb5_util − Kerberos database maintenance utility


kdb5_util [−r realm] [−d dbname] [−k mkeytype] [−kv mkeyVNO] [−M mkeyname] [−m] [−sf stashfilename] [−P password] [−x db_args] command [command_options]


kdb5_util allows an administrator to perform maintenance procedures on the KDC database. Databases can be created, destroyed, and dumped to or loaded from ASCII files. kdb5_util can create a Kerberos master key stash file or perform live rollover of the master key.

When kdb5_util is run, it attempts to acquire the master key and open the database. However, execution continues regardless of whether or not kdb5_util successfully opens the database, because the database may not exist yet or the stash file may be corrupt.

Note that some KDC database modules may not support all kdb5_util commands.


−r realm

specifies the Kerberos realm of the database.

−d dbname

specifies the name under which the principal database is stored; by default the database is that listed in kdc.conf(5). The password policy database and lock files are also derived from this value.

−k mkeytype

specifies the key type of the master key in the database. The default is given by the master_key_type variable in kdc.conf(5).

−kv mkeyVNO

Specifies the version number of the master key in the database; the default is 1. Note that 0 is not allowed.

−M mkeyname

principal name for the master key in the database. If not specified, the name is determined by the master_key_name variable in kdc.conf(5).


specifies that the master database password should be read from the keyboard rather than fetched from a file on disk.

−sf stash_file

specifies the stash filename of the master database password. If not specified, the filename is determined by the key_stash_file variable in kdc.conf(5).

−P password

specifies the master database password. Using this option may expose the password to other users on the system via the process list.

−x db_args

specifies database−specific options. See kadmin(1) for supported options.



create [−s]

Creates a new database. If the −s option is specified, the stash file is also created. This command fails if the database already exists. If the command is successful, the database is opened just as if it had already existed when the program was first run.


destroy [−f]

Destroys the database, first overwriting the disk sectors and then unlinking the files, after prompting the user for confirmation. With the −f argument, does not prompt the user.


stash [−f keyfile]

Stores the master principal's keys in a stash file. The −f argument can be used to override the keyfile specified in kdc.conf(5).


dump [−b7|−r13|−r18] [−verbose] [−mkey_convert] [−new_mkey_file mkey_file] [−rev] [−recurse] [filename [principals...]]

Dumps the current Kerberos and KADM5 database into an ASCII file. By default, the database is dumped in current format, "kdb5_util load_dump version 7". If filename is not specified, or is the string "−", the dump is sent to standard output. Options:


causes the dump to be in the Kerberos 5 Beta 7 format ("kdb5_util load_dump version 4"). This was the dump format produced on releases prior to 1.2.2.


causes the dump to be in the Kerberos 5 1.3 format ("kdb5_util load_dump version 5"). This was the dump format produced on releases prior to 1.8.


causes the dump to be in the Kerberos 5 1.8 format ("kdb5_util load_dump version 6"). This was the dump format produced on releases prior to 1.11.


causes the name of each principal and policy to be printed as it is dumped.


prompts for a new master key. This new master key will be used to re−encrypt principal key data in the dumpfile. The principal keys themselves will not be changed.

−new_mkey_file mkey_file

the filename of a stash file. The master key in this stash file will be used to re−encrypt the key data in the dumpfile. The key data in the database will not be changed.


dumps in reverse order. This may recover principals that do not dump normally, in cases where database corruption has occurred.


causes the dump to walk the database recursively (btree only). This may recover principals that do not dump normally, in cases where database corruption has occurred. In cases of such corruption, this option will probably retrieve more principals than the −rev option will.

Changed in version 1.15: Release 1.15 restored the functionality of the −recurse option.

Changed in version 1.5: The −recurse option ceased working until release 1.15, doing a normal dump instead of a recursive traversal.


load [−b7|−r13|−r18] [−hash] [−verbose] [−update] filename

Loads a database dump from the named file into the named database. If no option is given to determine the format of the dump file, the format is detected automatically and handled as appropriate. Unless the −update option is given, load creates a new database containing only the data in the dump file, overwriting the contents of any previously existing database. Note that when using the LDAP KDC database module, the −update flag is required.



requires the database to be in the Kerberos 5 Beta 7 format ("kdb5_util load_dump version 4"). This was the dump format produced on releases prior to 1.2.2.


requires the database to be in Kerberos 5 1.3 format ("kdb5_util load_dump version 5"). This was the dump format produced on releases prior to 1.8.


requires the database to be in Kerberos 5 1.8 format ("kdb5_util load_dump version 6"). This was the dump format produced on releases prior to 1.11.


stores the database in hash format, if using the DB2 database type. If this option is not specified, the database will be stored in btree format. This option is not recommended, as databases stored in hash format are known to corrupt data and lose principals.


causes the name of each principal and policy to be printed as it is dumped.


records from the dump file are added to or updated in the existing database. Otherwise, a new database is created containing only what is in the dump file and the old one destroyed upon successful completion.


ark [−e enc:salt,...] principal

Adds new random keys to principal at the next available key version number. Keys for the current highest key version number will be preserved. The −e option specifies the list of encryption and salt types to be used for the new keys.


add_mkey [−e etype] [−s]

Adds a new master key to the master key principal, but does not mark it as active. Existing master keys will remain. The −e option specifies the encryption type of the new master key; see Encryption_types in kdc.conf(5) for a list of possible values. The −s option stashes the new master key in the stash file, which will be created if it doesn't already exist.

After a new master key is added, it should be propagated to replica servers via a manual or periodic invocation of kprop(8). Then, the stash files on the replica servers should be updated with the kdb5_util stash command. Once those steps are complete, the key is ready to be marked active with the kdb5_util use_mkey command.


use_mkey mkeyVNO [time]

Sets the activation time of the master key specified by mkeyVNO. Once a master key becomes active, it will be used to encrypt newly created principal keys. If no time argument is given, the current time is used, causing the specified master key version to become active immediately. The format for time is getdate string.

After a new master key becomes active, the kdb5_util update_princ_encryption command can be used to update all principal keys to be encrypted in the new master key.



List all master keys, from most recent to earliest, in the master key principal. The output will show the kvno, enctype, and salt type for each mkey, similar to the output of kadmin(1) getprinc. A * following an mkey denotes the currently active master key.


purge_mkeys [−f] [−n] [−v]

Delete master keys from the master key principal that are not used to protect any principals. This command can be used to remove old master keys all principal keys are protected by a newer master key.


does not prompt for confirmation.


performs a dry run, showing master keys that would be purged, but not actually purging any keys.


gives more verbose output.


update_princ_encryption [−f] [−n] [−v] [princ−pattern]

Update all principal records (or only those matching the princ−pattern glob pattern) to re−encrypt the key data using the active database master key, if they are encrypted using a different version, and give a count at the end of the number of principals updated. If the −f option is not given, ask for confirmation before starting to make changes. The −v option causes each principal processed to be listed, with an indication as to whether it needed updating or not. The −n option performs a dry run, only showing the actions which would have been taken.


tabdump [−H] [−c] [−e] [−n] [−o outfile] dumptype

Dump selected fields of the database in a tabular format suitable for reporting (e.g., using traditional Unix text processing tools) or importing into relational databases. The data format is tab−separated (default), or optionally comma−separated (CSV), with a fixed number of columns. The output begins with a header line containing field names, unless suppression is requested using the −H option.

The dumptype parameter specifies the name of an output table (see below).



suppress writing the field names in a header line


use comma separated values (CSV) format, with minimal quoting, instead of the default tab−separated (unquoted, unescaped) format


write empty hexadecimal string fields as empty fields instead of as "−1".


produce numeric output for fields that normally have symbolic output, such as enctypes and flag names. Also requests output of time stamps as decimal POSIX time_t values.

−o outfile

write the dump to the specified output file instead of to standard output

Dump types:

principal encryption key information, including actual key data (which is still encrypted in the master key)


principal name


index of this key in the principal's key list


key version number


encryption type


key data as a hexadecimal string


salt type


salt data as a hexadecimal string


principal encryption key information (as in keydata above), excluding actual key data


principal boolean attributes. Flag names print as hexadecimal numbers if the −n option is specified, and all flag positions are printed regardless of whether or not they are set. If −n is not specified, print all known flag names for each principal, but only print hexadecimal flag names if the corresponding flag is set.


principal name


flag name


boolean value (0 for clear, or 1 for set)


state information used for tracking repeated password failures


principal name


time stamp of most recent successful authentication


time stamp of most recent failed authentication


count of failed attempts


principal metadata


principal name


name of last principal to modify this principal


timestamp of last modification


timestamp of last password change


policy object name


key version number of the master key that encrypts this principal's key data


key version number of the history key that encrypts the key history data for this principal


string attributes (key/value pairs)


principal name


attribute name


attribute value


per−principal ticket policy data, including maximum ticket lifetimes


principal name


principal expiration date


password expiration date


maximum ticket lifetime


maximum renewable ticket lifetime


$ kdb5_util tabdump −o keyinfo.txt keyinfo
$ cat keyinfo.txt
name        keyindex        kvno    enctype salttype        salt
K/M@EXAMPLE.COM     0       1       aes256−cts−hmac−sha384−192      normal  −1
foo@EXAMPLE.COM     0       1       aes128−cts−hmac−sha1−96 normal  −1
bar@EXAMPLE.COM     0       1       aes128−cts−hmac−sha1−96 normal  −1
$ sqlite3
sqlite> .mode tabs
sqlite> .import keyinfo.txt keyinfo
sqlite> select * from keyinfo where enctype like 'aes256−%';
K/M@EXAMPLE.COM     1       1       aes256−cts−hmac−sha384−192      normal  −1
sqlite> .quit
$ awk −F'\t' '$4 ~ /aes256−/ { print }' keyinfo.txt
K/M@EXAMPLE.COM     1       1       aes256−cts−hmac−sha384−192      normal  −1


See kerberos(7) for a description of Kerberos environment variables.


kadmin(1), kerberos(7)




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