pam_krb5(5)						   System Administrator's Manual					       pam_krb5(5)

NAME

       pam_krb5 - Kerberos 5 authentication

DESCRIPTION

       pam_krb5.so  reads  its	configuration information from the appdefaults section of krb5.conf(5).  You should read the krb5.conf(5) man page
       before continuing here.	The module expects its configuration information to be in the pam subsection of the appdefaults section.

DIRECTIVES

       Directives which take a true, false, or a PAM service name can also be selectively disabled for specific PAM  services  using  the  related
       "no_" option (exceptions to "debug = true" can be made using "no_debug", for example).

       debug = true|false|service [...]
	      turns on debugging via syslog(3).  Debug messages are logged with priority LOG_DEBUG.

       debug_sensitive = true|false|service [...]
	      turns on debugging of sensitive information via syslog(3).  Debug messages are logged with priority LOG_DEBUG.

       afs_cells = cell.example.com [...]
	      tells  pam_krb5.so  to obtain tokens for the listed cells, in addition to the local cell and the cell which contains the user's home
	      directory, for the user.	The module will guess the principal name of the AFS service for the listed cells, or it can  be  specified
	      by listing cells in the form cellname=principalname.

       always_allow_localname = true|false|service [...]
	      tells  pam_krb5.so,  when  performing  an authorization check using the target user's .k5login file, to always allow access when the
	      principal name being authenticated maps to the local user's name (as configured using the auth_to_local_names and auth_to_local set-
	      tings  in  krb5.conf(5),	if  your  implementation provides those settings).  Otherwise, if the file exists and can be read, but the
	      principal is not explicitly listed, access is typically denied.  This setting is disabled by default.

       armor = true|false|service [...]
	      attempt to use armoring when communicating with the KDC.	This option is currently mainly only useful for  testing,  as  the  keytab
	      method  should  not  be expected to work when the module is called from an unprivileged process, and the pkinit method requires that
	      the KDC is properly configured to offer anonymous PKINIT, and that the client is also properly configured to  trust  the	KDC's  CA.
	      The default is false.

       armor_strategy = keytab,pkinit
	      controls	how  the  module  will	attempt to obtain tickets for use as armor. The value should be a comma-separated list of methods.
	      Supported methods include ketyab and pkinit.  The default is keytab,pkinit.

       banner = Kerberos 5
	      specifies what sort of password the module claims to be changing whenever it is called upon to change  passwords.   The  default	is
	      Kerberos 5.

       ccache_dir = /var/tmp
	      specifies the directory in which to place credential cache files.  The default is /tmp.

       ccname_template = KEYRING:krb5cc_%U_%P

       ccname_template = FILE:%d/krb5cc_%U_XXXXXX
	      specifies  the  location	in  which to place the user's session-specific credential cache.  This value is treated as a template, and
	      these sequences are substituted:
		%u login name
		%U login UID
		%p principal name
		%r principal's realm name
		%h home directory
		%d the default ccache directory (as set with ccache_dir)
		%P the current process ID
		%% literal '%'

	      If the resulting template does not end with "XXXXXX", a suffix will be added to the  configured  value.	If  not  set,  the  module
	      attempts to read the default used by libkrb5 from krb5.conf(5), and if one is not found, the default is FILE:%d/krb5cc_%U_XXXXXX".

       chpw_prompt = true|false|service [...]
	      tells  pam_krb5.so  to allow expired passwords to be changed during authentication attempts.  While this is the traditional behavior
	      exhibited by "kinit", it is inconsistent with the behavior expected by PAM, which expects authentication	to  (appear  to)  succeed,
	      only  to have password expiration be flagged by a subsequent call to the account management function.  Some applications which don't
	      handle password expiration correctly will fail unconditionally if the user's password is expired, and  this  flag  can  be  used	to
	      attempt to work around this bug in those applications.  The default is false.

       cred_session=true|false|service [...]
	      specifies  that pam_krb5 should create and destroy credential caches, as it does when the calling application opens and closes a PAM
	      session, when the calling application establishes and deletes PAM credentials.  This is done to compensate  for  applications  which
	      expect to create a credential cache but which don't use PAM session management.  It is usually a harmless redundancy in applications
	      which don't require it, so this option is enabled by default except for this list of services: "sshd".

       external = true|false|sshd ftp [...]
	      tells pam_krb5.so to use Kerberos credentials provided by the calling application during session setup.  This is most  often  useful
	      for obtaining AFS tokens.  The default is "sshd sshd-rekey gssftp".

       ignore_afs=true|false|service [...]
	      tells  pam_krb5.so  to  completely ignore the presence of AFS, preventing any attempts to obtain new tokens on behalf of the calling
	      application.

       ignore_k5login=true|false|service [...]
	      specifies which other not pam_krb5 should skip checking the user's .k5login file to verify that the principal  name  of  the  client
	      being  authenticated  is authorized to access the user account.  (Actually, the check is performed by a function offered by the Ker-
	      beros library, which controls which files it will consult.)  The default is false, which causes pam_krb5 to perform the check.

       ignore_unknown_principals=true|false|service [...]

       ignore_unknown_spn=true|false|service [...]

       ignore_unknown_upn=true|false|service [...]
	      specifies which other not pam_krb5 should return a PAM_IGNORE code to libpam instead of PAM_USER_UNKNOWN	for  users  for  whom  the
	      determined principal name is expired or does not exist.

       initial_prompt=true|false|service [...]
	      tells  pam_krb5.so  whether or not to ask for a password before attempting authentication.  If one is needed and pam_krb5.so has not
	      prompted for it, the Kerberos library should trigger a request for a password.

       keytab = FILE:/etc/krb5.keytab

       keytab = FILE:/etc/krb5.keytab imap=FILE:/etc/imap.keytab
	      specifies the name of a keytab file to search for a service key for use in validating TGTs.  The location can be specified on a per-
	      service basis by specifying a list of locations in the form pam_service=location.  The default is FILE:/etc/krb5.keytab.

       mappings = regex1 regex2 [...]
	      specifies  that  pam_krb5 should derive the user's principal name from the Unix user name by first checking if the user name matches
	      regex1, and formulating a principal name using regex2.  For example, "mappings = ^EXAMPLE\(.*)$ $1@EXAMPLE.COM" would map any  user
	      with  a  name  of the form "EXAMPLEwhatever" to a principal name of "whatever@EXAMPLE.COM".  This is primarily targeted at allowing
	      pam_krb5 to be used to authenticate users whose user information is provided by  winbindd(8).   This  will  frequently  require  the
	      reverse to be configured by setting up an auth_to_local rule elsewhere in krb5.conf(5).

       minimum_uid = 0
	      specifies  the  minimum  UID  of	users being authenticated.  If a user with a UID less than this value attempts authentication, the
	      request will be ignored.

       multiple_ccaches=true|false|service [...]
	      specifies that pam_krb5 should maintain multiple credential caches for applications that both set credentials and open  a  PAM  ses-
	      sion,  but  which  set  the KRB5CCNAME variable after doing only one of the two.	This option is usually not necessary for most ser-
	      vices.

       preauth_options =
	      controls the preauthentication options which pam_krb5 passes to libkrb5, if the system-defaults need to be overridden.  The list	is
	      treated as a template, and these sequences are substituted:

		%u login name
		%U login UID
		%p principal name
		%r principal's realm name
		%h home directory
		%d the default ccache directory (as set with ccache_dir)
		%P the current process ID
		%% literal '%'

	      A list of recognized values should be listed in the kinit(1) manual page as parameters for its -X option.

       null_afs=true|false|service [...]
	      tells pam_krb5.so, when it attempts to set tokens, to try to get credentials for services with names which resemble afs@REALM before
	      attempting to get credentials for services with names resembling afs/cell@REALM.	The default is to assume that the cell's  name	is
	      the instance in the AFS service's Kerberos principal name.

       pwhelp = filename
	      specifies  the  name  of a text file whose contents will be displayed to clients who attempt to change their passwords.  There is no
	      default.

       subsequent_prompt = true|false|service [...]
	      controls whether or not pam_krb5.so will allow the Kerberos library to ask the user for a password or other information, if the pre-
	      viously-entered  password  is  somehow  insufficient for authenticating the user.  This is commonly needed to allow a user to log in
	      when that user's password has expired.  The default is false during password changes, and true otherwise.

	      If the calling application does not properly support PAM conversations (possibly due to limitations of a network protocol  which	it
	      is  serving),  this  may	be  need to be disabled for that application to prevent it from supplying the user's current password in a
	      password-changing situation when a new password is called for.

       tokens = true|false|service [...]
	      signals that pam_krb5.so should create an AFS PAG and obtain tokens during authentication in addition to	session  setup.   This	is
	      primarily useful in server applications which need to access a user's files but which do not open PAM sessions before doing so.  For
	      correctly-written applications, this flag is not necessary.

       token_strategy = rxk5,2b[,...]
	      controls how, and using which format, pam_krb5.so should attempt to set AFS tokens for the user's session.  By default,  the  module
	      is configured with "token_strategy = 2b".  Recognized strategy names include:
	       rxk5  rxk5 (requires OpenAFS 1.6 or later)
	       2b    rxkad "2b" (requires OpenAFS 1.2.8 or later)

       trace = true|false|service [...]
	      turns on libkrb5's library tracing.  Trace messages are logged to syslog(3) with priority LOG_DEBUG.

       use_shmem = true|false|service [...]
	      tells  pam_krb5.so  to  pass  credentials  from the authentication service function to the session management service function using
	      shared memory for specific services.  By default, the module is configured with "use_shmem = sshd".

       validate = true|false|service [...]
	      specifies whether or not to attempt validation of the TGT using the local keytab.   The  default	is  true.   The  libdefaults  ver-
	      ify_ap_req_nofail  setting  can affect whether or not errors reading the keytab which are encountered during validation will be sup-
	      pressed.

       validate_user_user = true|false|service [...]
	      specifies whether or not, when attempting validation of the TGT, to attempt user-to-user authentication using a previously-obtainted
	      TGT in the default ccache if validation can't be performed using a keytab.  The default is false.

EXAMPLE

       [appdefaults]
	 pam = {
	   validate = true
	   ccache_dir = /var/tmp
	   external = sshd
	   tokens = imap ftpd
	   TEST.EXAMPLE.COM = {
	     debug = true
	     afs_cells = testcell.example.com othercell.example.com
	     keytab = FILE:/etc/krb5.keytab httpd=FILE:/etc/httpd.keytab
	   }
	 }

FILES

       /etc/krb5.conf

SEE ALSO

       pam_krb5(8)

BUGS

       Probably,  but let's hope not.  If you find any, please file them in the bug database at http://bugzilla.redhat.com/ against the "pam_krb5"
       component.

AUTHOR

       Nalin Dahyabhai <nalin@redhat.com>

Red Hat Linux							    2013/09/21							       pam_krb5(5)