Files Reference

user File

Purpose

Contains extended user attributes.

Description

The /etc/security/user file contains extended user attributes. This is an ASCII file that contains attribute stanzas for users. The mkuser command creates a stanza in this file for each new user and initializes its attributes with the default attributes defined in the /usr/lib/security/mkuser.default file.

Each stanza in the /etc/security/user file is identified by a user name, followed by a : (colon), and contains comma-separated attributes in the Attribute=Value form. If an attribute is not defined for a user, either the default stanza or the default value for the attribute is used. You can have multiple default stanzas in the /etc/security/group file. A default stanza applies to all of the stanzas that follow, but does not apply to the stanzas preceding it.

Each attribute is ended by a new-line character, and each stanza is ended by an additional new-line character. For an example of a stanza, see the Examples section.

Attributes

If you have the proper authority, you can set the following user attributes:

account_locked	Indicates if the user account is locked. Possible values include: `true` The user's account is locked. The values `yes`, `true`, and `always` are equivalent. The user is denied access to the system. `false` The user's account is not locked. The values `no`, `false`, and `never` are equivalent. The user is allowed access to the system. This is the default value.
admin	Defines the administrative status of the user. Possible values are: `true` The user is an administrator. Only the root user can change the attributes of users defined as administrators. `false` The user is not an administrator. This is the default value.
admgroups	Lists the groups the user administrates. The Value parameter is a comma-separated list of group names.
auditclasses	Lists the user's audit classes. The Value parameter is a list of comma-separated classes, or a value of `ALL` to indicate all audit classes.
auth1	Lists additional mandatory methods for authenticating the user. The auth1 attribute has been deprecated and may not be supported in a future release. The SYSTEM attribute should be used instead. The authentication process will fail if any of the methods specified by the auth1 attribute fail. The Value parameter is a comma-separated list of Method;Name pairs. The Method parameter is the name of the authentication method. The Name parameter is the user to authenticate. If you do not specify a Name parameter, the name of the user being authenticated is used. Valid authentication methods for the auth1 and auth2 attributes are defined in the /etc/security/login.cfg file.
auth2	Lists additional optional methods for authenticating the user. The auth2 attribute has been deprecated and may not be supported in a future release. The SYSTEM attribute should be used instead. The authentication process will not fail if any of the methods specified by the auth2 attribute fail. The Value parameter is a comma-separated list of Method;Name pairs. The Method parameter is the name of the authentication method. The Name parameter is the user to authenticate. If you do not specify a Name parameter, the name of the user being authenticated is used.
daemon	Indicates whether the user specified by the Name parameter can execute programs using the src (system resource controller) daemon. Possible values are: `true` The user can initiate src sessions. This is the default. `false` The user cannot initiate src sessions.
dce_export	Allows the DCE registry to overwrite the local user information with the DCE user information during a DCE export operation. Possible values are: `true` Local user information will be overwritten. `false` Local user information will not be overwritten.
dictionlist	Defines the password dictionaries used by the composition restrictions when checking new passwords. The password dictionaries are a list of comma-separated, absolute path names that are evaluated from left to right. All dictionary files and directories must be write-protected from all users except root. The dictionary files are formatted one word per line. The word begins in the first column and terminates with a new-line character. Only 7-bit ASCII words are supported for passwords. If text processing is installed on your system, the recommended dictionary file is the /usr/share/dict/words file.
expires	Identifies the expiration date of the account. The Value parameter is a 10-character string in the MMDDhhmmyy form, where MM = month, DD = day, hh = hour, mm = minute, and yy = last 2 digits of the years 1939 through 2038. All characters are numeric. If the Value parameter is 0, the account does not expire. The default is 0. See the date command for more information.
histexpire	Designates the period of time (in weeks) that a user cannot reuse a password. The value is a decimal integer string. The default is 0, indicating that no time limit is set.
histsize	Designates the number of previous passwords a user cannot reuse. The value is a decimal integer string. The default is 0.
login	Indicates whether the user can log in to the system with the login command. Possible values are: `true` The user can log in to the system. This is the default. `false` The user cannot log in to the system.
logintimes	Specifies the times, days, or both, the user is allowed to access the system. The value is a comma-separated list of entries of the following form: [!]:time-time -or- [!]day[-day][:time-time] -or- [!]date[-date][:time-time] The day variable must be one digit between 0 and 6 that represents one of the days of the week. A 0 (zero) indicates Sunday and a 6 indicates Saturday. The time variable is 24-hour military time (1700 is 5:00 p.m.). Leading zeroes are required. For example, you must enter `0800,` not `800`. The time variable must be four characters in length, and there must be a leading colon (:). An entry consisting of only a time specification applies to every day. The start hour of a time value must be less than the end hour. The date variable is a four digit string in the form mmdd. mm represents the calendar month and dd represents the day number. For example `0001` represents January 1. dd may be `00` to indicate the entire month, if the entry is not a range, or indicating the first or last day of the month depending on whether it appears as part of the start or end of a range. For example, `0000` indicates the entire month of January. `0600` indicates the entire month of June. `0311-0500` indicates April 11 through the last day of June. Entries in this list specify times that a user is allowed or denied access to the system. Entries not preceded by an `!` (exclamation point) allow access and are called ALLOW entries. Entries prefixed with an `!` (exclamation point) deny access to the system and are called DENY entries. The `!` operator applies to only one entry, not the whole restriction list. It must appear at the beginning of each entry.
loginretries	Defines the number of unsuccessful login attempts allowed after the last successful login before the system locks the account. The value is a decimal integer string. A zero or negative value indicates that no limit exists. Once the user's account is locked, the user will not be able to log in until the system administrator resets the user's `unsuccessful_login_count` attribute in the /etc/security/lastlog file to be less than the value of loginretries. To do this, enter the following: chsec -f /etc/security/lastlog -s username -a \ unsuccessful_login_count=0
maxage	Defines the maximum age (in weeks) of a password. The password must be changed by this time. The value is a decimal integer string. The default is a value of 0, indicating no maximum age.
maxexpired	Defines the maximum time (in weeks) beyond the maxage value that a user can change an expired password. After this defined time, only an administrative user can change the password. The value is a decimal integer string. The default is -1, indicating no restriction is set. If the maxexpired attribute is 0, the password expires when the maxage value is met. If the maxage attribute is 0, the maxexpired attribute is ignored.
maxrepeats	Defines the maximum number of times a character can be repeated in a new password. Since a value of 0 is meaningless, the default value of 8 indicates that there is no maximum number. The value is a decimal integer string.
minage	Defines the minimum age (in weeks) a password must be before it can be changed. The value is a decimal integer string. The default is a value of 0, indicating no minimum age.
minalpha	Defines the minimum number of alphabetic characters that must be in a new password. The value is a decimal integer string. The default is a value of 0, indicating no minimum number.
mindiff	Defines the minimum number of characters required in a new password that were not in the old password. The value is a decimal integer string. The default is a value of 0, indicating no minimum number.
minlen	Defines the minimum length of a password. The value is a decimal integer string. The default is a value of 0, indicating no minimum length. The maximum value allowed is 8. This attribute is determined by the minalpha attribute value added to the minother attribute value. If the sum of these values is greater than the minlen attribute value, the minimum length is set to the result.
minother	Defines the minimum number of non-alphabetic characters that must be in a new password. The value is a decimal integer string. The default is a value of 0, indicating no minimum number.
pwdchecks	Defines the password restriction methods enforced on new passwords. The value is a list of comma-separated method names and is evaluated from left to right. A method name is either an absolute path name or a path name relative to /usr/lib of an executable load module.
pwdwarntime	Defines the number of days before the system issues a warning that a password change is required. The value is a decimal integer string. A zero or negative value indicates that no message is issued. The value must be less than the difference of the maxage and minage attributes. Values greater than this difference are ignored, and a message is issued when the minage value is reached.
registry	Defines the authentication registry where the user is administered. It is used to resolve a remotely administered user to the local administered domain. This situation may occur when network services unexpectedly fail or network databases are replicated locally. Example values are `files` or `NIS` or `DCE`.
rlogin	Permits access to the account from a remote location with the telnet or rlogin commands. Possible values are: `true` The user account can be accessed remotely. This is the default rlogin value. `false` The user account cannot be accessed remotely.
su	Indicates whether another user can switch to the specified user account with the su command. Possible values are: `true` Another user can switch to the specified account. This is the default. `false` Another user cannot switch to the specified account.
sugroups	Lists the groups that can use the su command to switch to the specified user account. The Value parameter is a comma-separated list of group names, or a value of `ALL` to indicate all groups. An ! (exclamation point) in front of a group name excludes that group. If this attribute is not specified, all groups can switch to this user account with the su command.
SYSTEM	Defines the system authentication mechanism for the user. The value may be an expression describing which authentication methods are to be used or it may be the keyword `NONE`. The SYSTEM mechanism is always used to authenticate the user, regardless of the value of the auth1 and auth2 attributes. If the SYSTEM attribute is set to `NONE`, authentication is only performed using the auth1 and auth2 attributes. If the auth1 and auth2 attributes are blank or ignored, as with the TCP socket daemons (ftpd, rexecd and rshd), no authentication will be performed. The method names compat, files and NIS are provided by the security library. Additional methods may be defined in the file /usr/lib/security/methods.cfg. Specify the value for SYSTEM using the following grammar: "SYSTEM" ::= EXPRESSION EXPRESSION ::= PRIMITIVE \| "("EXPRESSION")" \| EXPRESSION OPERATOR EXPRESSION PRIMITIVE ::= METHOD \| METHOD "["RESULT"]" RESULT ::= "SUCCESS" \| "FAILURE" \| "NOTFOUND" \| "UNAVAIL" \| "" OPERATOR ::= "AND" \| "OR" METHOD ::= "compat" \| "files" \| "NONE" \| [a-z,A-Z,0-9] An example of the syntax is: SYSTEM = "DCE OR DCE[UNAVAIL] AND compat"
tpath	Indicates the user's trusted path status. The possible values are: `always` The user can only execute trusted processes. This implies that the user's initial program is in the trusted shell or some other trusted process. `notsh` The user cannot invoke the trusted shell on a trusted path. If the user enters the secure attention key (SAK) after logging in, the login session ends. `nosak` The secure attention key (SAK) is disabled for all processes run by the user. Use this value if the user transfers binary data that may contain the SAK sequence. This is the default value. `on` The user has normal trusted path characteristics and can invoke a trusted path (enter a trusted shell) with the secure attention key (SAK).
ttys	Lists the terminals that can access the account specified by the Name parameter. The Value parameter is a comma-separated list of full path names, or a value of `ALL` to indicate all terminals. The values of `RSH` and `REXEC` also can be used as terminal names. An ! (exclamation point) in front of a terminal name excludes that terminal. If this attribute is not specified, all terminals can access the user account. If the Value parameter is not `ALL`, then `/dev/pts` must be specified for network logins to work.
umask	Determines file permissions. This value, along with the permissions of the creating process, determines a file's permissions when the file is created. The default is 022.

Changing the user File

You should access this file through the commands and subroutines defined for this purpose. You can use the following commands to change the user file:

chuser
lsuser
mkuser
rmuser

The mkuser command creates an entry for each new user in the /etc/security/user file and initializes its attributes with the attributes defined in the /usr/lib/security/mkuser.default file. To change attribute values, use the chuser command. To display the attributes and their values, use the lsuser command. To remove a user, use the rmuser command.

To write programs that affect attributes in the /etc/security/user file, use the subroutines listed in Related Information.

Security

Access Control

This file should grant read (r) access only to the root user and members of the security group. Access for other users and groups depends upon the security policy for the system. Only the root user should have write (w) access.

Auditing Events

Event	Information
S_USER_WRITE	file name

Examples

A typical stanza looks like the following example for user dhs:

dhs:
    login = true
    rlogin = false
    ttys = /dev/console
    sugroups = security,!staff
    expires = 0531010090
    tpath = on
    admin = true
    auth1 = SYSTEM,METH2;dhs

To allow all ttys except /dev/tty0 to access the user account, change the ttys entry so that it reads as follows:
```
ttys = !/dev/tty0,ALL
```

Files

/etc/group	Contains the basic group attributes.
/etc/passwd	Contains the basic user attributes.
/etc/security/audit/config	Contains audit system configuration information.
/etc/security/environ	Contains the environment attributes of users.
/etc/security/group	Contains the extended attributes of groups.
/etc/security/limits	Contains the process resource limits of users.
/etc/security/login.cfg	Contains configuration information for user log in and authentication.
/etc/security/passwd	Contains password information.
/usr/lib/security/mkuser.default	Contains default user configurations.
/etc/security/user	Contains extended user attributes.
/etc/security/lastlog	Contains last login information.

Related Information

The chuser command, lsuser command, mkuser command, rmuser command.

The enduserdb subroutine, getuserattr subroutine, putuserattr subroutine, setuserdb subroutine.

For more information about the identification and authentication of users, discretionary access control, the trusted computing base, and auditing, refer to Security Administration and Users, Roles, and Passwords in AIX 5L Version 5.2 Security Guide.