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PAM_KRB5(8)		FreeBSD	System Manager's Manual		   PAM_KRB5(8)

NAME
     pam_krb5 -- Kerberos 5 PAM	module

SYNOPSIS
     /usr/lib/pam_krb5.so

DESCRIPTION
     The Kerberos 5 service module for PAM, typically /usr/lib/pam_krb5.so,
     provides functionality for	three PAM categories: authentication, account
     management, and password management.  It also provides null functions for
     session management.  The pam_krb5.so module is a shared object that can
     be	dynamically loaded to provide the necessary functionality upon demand.
     Its path is specified in the PAM configuration file.

   Kerberos 5 Authentication Module
     The Kerberos 5 authentication component provides functions	to verify the
     identity of a user	(pam_sm_authenticate())	and to set user	specific cre-
     dentials (pam_sm_setcred()).  pam_sm_authenticate() converts the supplied
     username into a Kerberos principal, by appending the default local	realm
     name.  It also supports usernames with explicit realm names.  If a	realm
     name is supplied, then upon a successful return, it changes the username
     by	mapping	the principal name into	a local	username (calling
     krb5_aname_to_localname()).  This typically just means the	realm name is
     stripped.

     It	prompts	the user for a password	and obtains a new Kerberos TGT for the
     principal.	 The TGT is verified by	obtaining a service ticket for the
     local host.

     When prompting for	the current password, the authentication module	will
     use the prompt ``Password for <principal>:''.

     The pam_sm_setcred() function stores the newly acquired credentials in a
     credentials cache,	and sets the environment variable KRB5CCNAME appropri-
     ately.  The credentials cache should be destroyed by the user at logout
     with kdestroy(1).

     The following options may be passed to the	authentication module:

     debug	     syslog(3) debugging information at	LOG_DEBUG level.

     no_warn	     suppress warning messages to the user.  These messages
		     include reasons why the user's authentication attempt was
		     declined.

     use_first_pass  If	the authentication module is not the first in the
		     stack, and	a previous module obtained the user's pass-
		     word, that	password is used to authenticate the user.  If
		     this fails, the authentication module returns failure
		     without prompting the user	for a password.	 This option
		     has no effect if the authentication module	is the first
		     in	the stack, or if no previous modules obtained the
		     user's password.

     try_first_pass  This option is similar to the use_first_pass option,
		     except that if the	previously obtained password fails,
		     the user is prompted for another password.

     forwardable     Obtain forwardable	Kerberos credentials for the user.

     no_ccache	     Do	not save the obtained credentials in a credentials
		     cache.  This is a useful option if	the authentication
		     module is used for	services such as ftp or	pop, where the
		     user would	not be able to destroy them.  [This is not a
		     recommendation to use the module for those	services.]

     ccache=name     Use name as the credentials cache.	 name must be in the
		     form type:residual.  The special tokens `%u', to desig-
		     nate the decimal UID of the user; and `%p', to designate
		     the current process ID; can be used in name.

     no_user_check   Do	not verify if a	user exists on the local system. This
		     option implies the	no_ccache option because there is no
		     secure local uid/gid for the cache	file.

   Kerberos 5 Account Management Module
     The Kerberos 5 account management component provides a function to	per-
     form account management, pam_sm_acct_mgmt().  The function	verifies that
     the authenticated principal is allowed to login to	the local user account
     by	calling	krb5_kuserok() (which checks the user's	.k5login file).

   Kerberos 5 Password Management Module
     The Kerberos 5 password management	component provides a function to
     change passwords (pam_sm_chauthtok()).  The username supplied (the	user
     running the passwd(1) command, or the username given as an	argument) is
     mapped into a Kerberos principal name, using the same technique as	in the
     authentication module.  Note that if a realm name was explicitly supplied
     during authentication, but	not during a password change, the mapping done
     by	the password management	module may not result in the same principal as
     was used for authentication.

     Unlike when changing a UNIX password, the password	management module will
     allow any user to change any principal's password (if the user knows the
     principal's old password, of course).  Also unlike	UNIX, root is always
     prompted for the principal's old password.

     The password management module uses the same heuristics as	kpasswd(1) to
     determine how to contact the Kerberos password server.

     The following options may be passed to the	password management module:

     debug	     syslog(3) debugging information at	LOG_DEBUG level.

     use_first_pass  If	the password management	module is not the first	in the
		     stack, and	a previous module obtained the user's old
		     password, that password is	used to	authenticate the user.
		     If	this fails, the	password management module returns
		     failure without prompting the user	for the	old password.
		     If	successful, the	new password entered to	the previous
		     module is also used as the	new Kerberos password.	If the
		     new password fails, the password management module
		     returns failure without prompting the user	for a new
		     password.

     try_first_pass  This option is similar to the use_first_pass option,
		     except that if the	previously obtained old	or new pass-
		     words fail, the user is prompted for them.

   Kerberos 5 Session Management Module
     The Kerberos 5 session management component provides functions to initi-
     ate (pam_sm_open_session()) and terminate (pam_sm_close_session())	ses-
     sions.  Since session management is not defined under Kerberos 5, both of
     these functions simply return success.  They are provided only because of
     the naming	conventions for	PAM modules.

ENVIRONMENT
     KRB5CCNAME	 Location of the credentials cache.

FILES
     /tmp/krb5cc_uid  default credentials cache	(uid is	the decimal UID	of the
		      user).
     $HOME/.k5login   file containing Kerberos principals that are allowed
		      access.

SEE ALSO
     kdestroy(1), passwd(1), syslog(3),	pam.conf(5), pam(8)

NOTES
     Applications should not call pam_authenticate() more than once between
     calls to pam_start() and pam_end()	when using the Kerberos	5 PAM module.

FreeBSD	10.1			  May 3, 2010			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | FILES | SEE ALSO | NOTES

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