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Diffstat (limited to 'modules/pam_unix/pam_unix.8')
| -rw-r--r-- | modules/pam_unix/pam_unix.8 | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/modules/pam_unix/pam_unix.8 b/modules/pam_unix/pam_unix.8 new file mode 100644 index 0000000..b396b66 --- /dev/null +++ b/modules/pam_unix/pam_unix.8 @@ -0,0 +1,285 @@ +'\" t +.\" Title: pam_unix +.\" Author: [see the "AUTHOR" section] +.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/> +.\" Date: 06/08/2020 +.\" Manual: Linux-PAM Manual +.\" Source: Linux-PAM Manual +.\" Language: English +.\" +.TH "PAM_UNIX" "8" "06/08/2020" "Linux-PAM Manual" "Linux\-PAM Manual" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +pam_unix \- Module for traditional password authentication +.SH "SYNOPSIS" +.HP \w'\fBpam_unix\&.so\fR\ 'u +\fBpam_unix\&.so\fR [\&.\&.\&.] +.SH "DESCRIPTION" +.PP +This is the standard Unix authentication module\&. It uses standard calls from the system\*(Aqs libraries to retrieve and set account information as well as authentication\&. Usually this is obtained from the /etc/passwd and the /etc/shadow file as well if shadow is enabled\&. +.PP +The account component performs the task of establishing the status of the user\*(Aqs account and password based on the following +\fIshadow\fR +elements: expire, last_change, max_change, min_change, warn_change\&. In the case of the latter, it may offer advice to the user on changing their password or, through the +\fBPAM_AUTHTOKEN_REQD\fR +return, delay giving service to the user until they have established a new password\&. The entries listed above are documented in the +\fBshadow\fR(5) +manual page\&. Should the user\*(Aqs record not contain one or more of these entries, the corresponding +\fIshadow\fR +check is not performed\&. +.PP +The authentication component performs the task of checking the users credentials (password)\&. The default action of this module is to not permit the user access to a service if their official password is blank\&. +.PP +A helper binary, +\fBunix_chkpwd\fR(8), is provided to check the user\*(Aqs password when it is stored in a read protected database\&. This binary is very simple and will only check the password of the user invoking it\&. It is called transparently on behalf of the user by the authenticating component of this module\&. In this way it is possible for applications like +\fBxlock\fR(1) +to work without being setuid\-root\&. The module, by default, will temporarily turn off SIGCHLD handling for the duration of execution of the helper binary\&. This is generally the right thing to do, as many applications are not prepared to handle this signal from a child they didn\*(Aqt know was +\fBfork()\fRd\&. The +\fBnoreap\fR +module argument can be used to suppress this temporary shielding and may be needed for use with certain applications\&. +.PP +The maximum length of a password supported by the pam_unix module via the helper binary is +\fIPAM_MAX_RESP_SIZE\fR +\- currently 512 bytes\&. The rest of the password provided by the conversation function to the module will be ignored\&. +.PP +The password component of this module performs the task of updating the user\*(Aqs password\&. The default encryption hash is taken from the +\fBENCRYPT_METHOD\fR +variable from +\fI/etc/login\&.defs\fR +.PP +The session component of this module logs when a user logins or leave the system\&. +.PP +Remaining arguments, supported by others functions of this module, are silently ignored\&. Other arguments are logged as errors through +\fBsyslog\fR(3)\&. +.SH "OPTIONS" +.PP +\fBdebug\fR +.RS 4 +Turns on debugging via +\fBsyslog\fR(3)\&. +.RE +.PP +\fBaudit\fR +.RS 4 +A little more extreme than debug\&. +.RE +.PP +\fBquiet\fR +.RS 4 +Turns off informational messages namely messages about session open and close via +\fBsyslog\fR(3)\&. +.RE +.PP +\fBnullok\fR +.RS 4 +The default action of this module is to not permit the user access to a service if their official password is blank\&. The +\fBnullok\fR +argument overrides this default\&. +.RE +.PP +\fBnullresetok\fR +.RS 4 +Allow users to authenticate with blank password if password reset is enforced even if +\fBnullok\fR +is not set\&. If password reset is not required and +\fBnullok\fR +is not set the authentication with blank password will be denied\&. +.RE +.PP +\fBtry_first_pass\fR +.RS 4 +Before prompting the user for their password, the module first tries the previous stacked module\*(Aqs password in case that satisfies this module as well\&. +.RE +.PP +\fBuse_first_pass\fR +.RS 4 +The argument +\fBuse_first_pass\fR +forces the module to use a previous stacked modules password and will never prompt the user \- if no password is available or the password is not appropriate, the user will be denied access\&. +.RE +.PP +\fBnodelay\fR +.RS 4 +This argument can be used to discourage the authentication component from requesting a delay should the authentication as a whole fail\&. The default action is for the module to request a delay\-on\-failure of the order of two second\&. +.RE +.PP +\fBuse_authtok\fR +.RS 4 +When password changing enforce the module to set the new password to the one provided by a previously stacked +\fBpassword\fR +module (this is used in the example of the stacking of the +\fBpam_cracklib\fR +module documented below)\&. +.RE +.PP +\fBauthtok_type=\fR\fB\fItype\fR\fR +.RS 4 +This argument can be used to modify the password prompt when changing passwords to include the type of the password\&. Empty by default\&. +.RE +.PP +\fBnis\fR +.RS 4 +NIS RPC is used for setting new passwords\&. +.RE +.PP +\fBremember=\fR\fB\fIn\fR\fR +.RS 4 +The last +\fIn\fR +passwords for each user are saved in +/etc/security/opasswd +in order to force password change history and keep the user from alternating between the same password too frequently\&. The MD5 password hash algorithm is used for storing the old passwords\&. Instead of this option the +\fBpam_pwhistory\fR +module should be used\&. +.RE +.PP +\fBshadow\fR +.RS 4 +Try to maintain a shadow based system\&. +.RE +.PP +\fBmd5\fR +.RS 4 +When a user changes their password next, encrypt it with the MD5 algorithm\&. +.RE +.PP +\fBbigcrypt\fR +.RS 4 +When a user changes their password next, encrypt it with the DEC C2 algorithm\&. +.RE +.PP +\fBsha256\fR +.RS 4 +When a user changes their password next, encrypt it with the SHA256 algorithm\&. The SHA256 algorithm must be supported by the +\fBcrypt\fR(3) +function\&. +.RE +.PP +\fBsha512\fR +.RS 4 +When a user changes their password next, encrypt it with the SHA512 algorithm\&. The SHA512 algorithm must be supported by the +\fBcrypt\fR(3) +function\&. +.RE +.PP +\fBblowfish\fR +.RS 4 +When a user changes their password next, encrypt it with the blowfish algorithm\&. The blowfish algorithm must be supported by the +\fBcrypt\fR(3) +function\&. +.RE +.PP +\fBgost_yescrypt\fR +.RS 4 +When a user changes their password next, encrypt it with the gost\-yescrypt algorithm\&. The gost\-yescrypt algorithm must be supported by the +\fBcrypt\fR(3) +function\&. +.RE +.PP +\fByescrypt\fR +.RS 4 +When a user changes their password next, encrypt it with the yescrypt algorithm\&. The yescrypt algorithm must be supported by the +\fBcrypt\fR(3) +function\&. +.RE +.PP +\fBrounds=\fR\fB\fIn\fR\fR +.RS 4 +Set the optional number of rounds of the SHA256, SHA512, blowfish, gost\-yescrypt, and yescrypt password hashing algorithms to +\fIn\fR\&. +.RE +.PP +\fBbroken_shadow\fR +.RS 4 +Ignore errors reading shadow information for users in the account management module\&. +.RE +.PP +\fBminlen=\fR\fB\fIn\fR\fR +.RS 4 +Set a minimum password length of +\fIn\fR +characters\&. The max\&. for DES crypt based passwords are 8 characters\&. +.RE +.PP +\fBno_pass_expiry\fR +.RS 4 +When set ignore password expiration as defined by the +\fIshadow\fR +entry of the user\&. The option has an effect only in case +\fIpam_unix\fR +was not used for the authentication or it returned authentication failure meaning that other authentication source or method succeeded\&. The example can be public key authentication in +\fIsshd\fR\&. The module will return +\fBPAM_SUCCESS\fR +instead of eventual +\fBPAM_NEW_AUTHTOK_REQD\fR +or +\fBPAM_AUTHTOK_EXPIRED\fR\&. +.RE +.PP +Invalid arguments are logged with +\fBsyslog\fR(3)\&. +.SH "MODULE TYPES PROVIDED" +.PP +All module types (\fBaccount\fR, +\fBauth\fR, +\fBpassword\fR +and +\fBsession\fR) are provided\&. +.SH "RETURN VALUES" +.PP +PAM_IGNORE +.RS 4 +Ignore this module\&. +.RE +.SH "EXAMPLES" +.PP +An example usage for +/etc/pam\&.d/login +would be: +.sp +.if n \{\ +.RS 4 +.\} +.nf +# Authenticate the user +auth required pam_unix\&.so +# Ensure users account and password are still active +account required pam_unix\&.so +# Change the user\*(Aqs password, but at first check the strength +# with pam_cracklib(8) +password required pam_cracklib\&.so retry=3 minlen=6 difok=3 +password required pam_unix\&.so use_authtok nullok yescrypt +session required pam_unix\&.so + +.fi +.if n \{\ +.RE +.\} +.sp +.SH "SEE ALSO" +.PP +\fBlogin.defs\fR(5), +\fBpam.conf\fR(5), +\fBpam.d\fR(5), +\fBpam\fR(8) +.SH "AUTHOR" +.PP +pam_unix was written by various people\&. |