KRB5_KEYTAB (3) | C library functions | Unix Manual Pages

KRB5_KEYTAB (3) | C library functions | Unix Manual Pages | :man▋

When a keytab-name is resolved, the type is matched with an internal list of keytab types. If there is no matching keytab type, the default keytab is used. The current default type is file. The default value can be changed in the configuration file /etc/krb5.conf by setting the variable [defaults]default_keytab_name.

The keytab types that are implemented in Heimdal are:

file	store the keytab in a file, the type’s name is KEYFILE. The residual part is a filename.
keyfile
	store the keytab in a AFS keyfile (usually `/usr/afs/etc/KeyFile`), the type’s name is AFSKEYFILE. The residual part is a filename.
krb4	the keytab is a Kerberos 4 `srvtab` that is on-the-fly converted to a keytab. The type’s name is krb4. The residual part is a filename.
memory
	The keytab is stored in a memory segment. This allows sensitive and/or temporary data not to be stored on disk. The type’s name is MEMORY. There are no residual part, the only pointer back to the keytab is the id returned by `krb5_kt_resolve`.

krb5_keytab_entry holds all data for an entry in a keytab file, like principal name, key-type, key, key-version number, etc. krb5_kt_cursor holds the current position that is used when iterating through a keytab entry with krb5_kt_start_seq_get, krb5_kt_next_entry, and krb5_kt_end_seq_get.

krb5_kt_ops contains the different operations that can be done to a keytab. This structure is normally only used when doing a new keytab-type implementation.

krb5_kt_resolve is the equivalent of an open(2) on keytab. Resolve the keytab name in name into a keytab in id. Returns 0 or an error. The opposite of krb5_kt_resolve is krb5_kt_close. krb5_kt_close frees all resources allocated to the keytab.

krb5_kt_default sets the argument id to the default keytab. Returns 0 or an error.

krb5_kt_default_name copy the name of the default keytab into name. Return 0 or KRB5_CONFIG_NOTENUFSPACE if namesize is too short.

krb5_kt_add_entry Add a new entry to the keytab id. KRB5_KT_NOWRITE is returned if the keytab is a readonly keytab.

krb5_kt_compare compares the passed in entry against principal, vno, and enctype. Any of principal, vno or enctype might be 0 which acts as a wildcard. Return TRUE if they compare the same, FALSE otherwise.

krb5_kt_copy_entry_contents copies the contents of in into out. Returns 0 or an error.

krb5_kt_get_name retrieves the name of the keytab keytab into name, namesize. Returns 0 or an error.

krb5_kt_get_type retrieves the type of the keytab keytab and store the prefix/name for type of the keytab into prefix, prefixsize. The prefix will have the maximum length of KRB5_KT_PREFIX_MAX_LEN (including terminating NUL). Returns 0 or an error.

krb5_kt_free_entry frees the contents of entry.

krb5_kt_start_seq_get sets cursor to point at the beginning of id. Returns 0 or an error.

krb5_kt_next_entry gets the next entry from id pointed to by cursor and advance the cursor. Returns 0 or an error.

krb5_kt_end_seq_get releases all resources associated with cursor.

krb5_kt_get_entry retrieves the keytab entry for principal, kvno, enctype into entry from the keytab id. Returns 0 or an error.

krb5_kt_read_service_key reads the key identified by ( principal, vno, enctype) from the keytab in keyprocarg (the default if == NULL) into *key. Returns 0 or an error.

krb5_kt_remove_entry removes the entry entry from the keytab id. Returns 0 or an error.

krb5_kt_register registers a new keytab type ops. Returns 0 or an error.

EXAMPLE

This is a minimalistic version of ktutil.

int
main (int argc, char **argv)
{
krb5_context context;
krb5_keytab keytab;
krb5_kt_cursor cursor;
krb5_keytab_entry entry;
krb5_error_code ret;
char *principal;

if (krb5_init_context (&context) != 0)
errx(1, "krb5_context");

ret = krb5_kt_default (context, &keytab);
if (ret)
krb5_err(context, 1, ret, "krb5_kt_default");

ret = krb5_kt_start_seq_get(context, keytab, &cursor);
if (ret)
krb5_err(context, 1, ret, "krb5_kt_start_seq_get");
while((ret = krb5_kt_next_entry(context, keytab, &entry, &cursor)) == 0){
krb5_unparse_name_short(context, entry.principal, &principal);
printf("principal: %s\n", principal);
free(principal);
krb5_kt_free_entry(context, &entry);
}
ret = krb5_kt_end_seq_get(context, keytab, &cursor);
if (ret)
krb5_err(context, 1, ret, "krb5_kt_end_seq_get");
krb5_free_context(context);
return 0;
}

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