passwd(4) Kernel Interfaces Manual passwd(4)
NAME
passwd - password file
SYNOPSIS
DESCRIPTION
contains the following information for each user:
o login name
o encrypted password
o numerical user ID
o numerical group ID
o reserved gecos ID
o initial working directory
o program to use as shell
This is an ASCII file. Each field within each user's entry is separated from the next by a colon. Each user is separated from the next by
a newline. This file resides in the directory. It can and does have general read permission and can be used, for example, to map numeri-
cal user IDs to names.
returns a pointer to a user's entry passwd structure declared in
The login name may only contain alphanumeric and underscore characters. The login name must start with an alpha character, unless the
NumericUsername product is installed, in which case, the first character can also be a decimal digit.
If the login directory is null, the user will be placed in by default. If the login shell is null, is used.
It is suggested that the range 0-99 not be used for user and group IDs so that IDs that might be assigned for system software do not con-
flict.
The gecos field may contain the following identification: user's full name, office location, extension, and home phone. The gecos field
can be set by use of the command and is displayed by the command (see chfn(1) and finger(1)). These two commands assume the information in
this field is in the order listed above. A portion of the user's real name can be represented in the gecos field by an character, which
some utilities (including expand by substituting the login name for it and shifting the first letter of the login name to uppercase.
Password Field
On a non-shadowed standard system, all password fields contain the actual encrypted password. On a shadowed standard system, all password
fields contain an `x', while the actual encrypted passwords reside in On a trusted system, all password fields contain a `*' and the actual
encrypted passwords reside in the Protected Password Database.
The following description of the password field applies only to the password field of an entry in that contains an actual encrypted pass-
word. See the shadow(4) manpage for details about encrypted passwords that reside in and see the section of this manpage for details about
encrypted passwords that reside on a trusted system.
If the password field is null, there is no password and no password is demanded on login. Otherwise, this field consists of an encrypted
password with an optional password aging subfield.
The encrypted password consists of 13 characters chosen from a 64-character set of "digits" described below, Login can be prevented by
entering in the password field a character that is not part of the set of digits (such as
The characters used to represent "digits" are for 0, for 1, through for 2 through 11, through for 12 through 37, and through for 38 through
63.
Password aging is put in effect for a particular user if his encrypted password in the password file is followed by a comma and a non-null
string of characters from the above alphabet. (Such a string must be introduced in the first instance by a superuser.) This string
defines the "age" needed to implement password aging.
UNIX keeps internal time stamps in a format with a base date of Thursday January 1, 1970. Because of this, passwd considers the beginning
of a week to be 00:00 GMT Thursday.
The first character of the age, M, denotes the maximum number of weeks for which a password is valid. A user who attempts to login after
his password has expired is forced to supply a new one. The next character, m, denotes the minimum period in weeks that must expire before
the password can be changed. The remaining two characters define the week when the password was last changed (a null string is equivalent
to zero). M and m have numerical values in the range 0 through 63 that correspond to the 64-character set of "digits" shown above.
If m = M = 0 (derived from the string or the user is forced to change his password next time he logs in (and the "age" disappears from his
entry in the password file). If m > M (signified, for example, by the string then only a superuser (not the user) can change the password.
Not allowing the user to ever change the password is discouraged.
SECURITY FEATURES
This section applies only to trusted systems. Note that HP-UX 11i Version 3 is the last release to support trusted systems functionality.
On a trusted system the password field always contains by default. Password and aging information are instead part of the Protected Pass-
word Database.
On trusted systems, the encrypted password for each user is stored in the file (where c is the first letter in user_name). Password infor-
mation files are not accessible to the public. The encrypted password can be longer than 13 characters. For example, the password file
for user is stored in In addition to the password, the user profiles in also have many other fields, including:
o numerical audit ID
o numerical audit flag
Like this file is an ASCII file. Fields within each user's entry are separated by colons. Refer to authcap(4) and prpwd(4) for details.
The passwords contained in take precedence over those contained in the encrypted password field of User authentication is done using the
encrypted passwords in this file. For a description of the password aging mechanism, see the section of passwd(1).
For more information about passwords and converting to a trusted system, see and sam(1M).
NETWORKING FEATURES
NIS
The file can have entries that begin with a plus or minus sign in the first column. Such lines are used to access the Network Information
System database. A line beginning with a plus is used to incorporate entries from the Network Information System. There are three styles
of entries:
Insert the entire contents
of the Network Information System password file at that point;
Insert the entry (if any) for
name from the Network Information System at that point
Insert the entries for all members of the network group
name at that point.
If a entry has a non-null password, directory, gecos, or shell field, they override what is contained in the Network Information System.
The numerical user ID and group ID fields cannot be overridden.
The file can also have lines beginning with a minus which disallow entries from the Network Information System. There are two styles of
entries:
Disallow any subsequent entries (if any) for
name.
Disallow any subsequent entries for all members of the network group
name.
NIS Warnings
The plus and minus features are NIS functionality; therefore, if NIS is not installed, they do not work. Also, these features work only
with
The uid of -2 is reserved for remote root access by means of NFS. The user name usually given to this uid is Since uids are stored as
signed values, the following define is included in to match the user
WARNINGS
The login shell for the root user (uid 0) must be to guarantee the system can always boot. Other shells such as sh, ksh, and csh are all
located under the directory which may not be mounted during earlier stages of the bootup process. Changing the login shell of the root
user to a value other than is allowed but may result in a non-functional system.
The information kept in the gecos field may conflict with unsupported or future uses of this field. Use of the gecos field for keeping
user identification information has not been formalized within any of the industry standards. The current use of this field is derived
from its use within the Berkeley Software Distribution. Future standards may define this field for other purposes.
The following fields have size limitations as noted:
o Login name field can be no longer than 8 characters, or 255 characters if the support of long user and group names is enabled on
the system;
o Initial working directory field can be no longer than 63 characters, or 310 characters if the support of long user and group
names is enabled on the system;
o Program field can be no longer than 44 characters.
o Results are unpredictable if these fields are longer than the limits specified above.
The following fields have numerical limitations as noted:
o The user ID is an integer value between 0 and inclusive. As a special case, -2 may be present.
o The group ID is an integer value between 0 and inclusive. As a special case -2 may be present.
o If either of these values are out of range, the functions reset the ID value to
HP-UX 11i Version 3 is the last release to support trusted systems functionality.
EXAMPLES
Shadow Password Example
If the system has been converted to a shadowed standard system, the password fields of user and user contain an 'x', and the actual
encrypted passwords reside in If it was a non-shadowed standard system, the password fields of user and user would contain the actual
encrypted passwords.
NIS Example
In the NIS example, there are specific entries for users and in case the Network Information System is out of order.
o User password entry in the Network Information System is incorporated without change.
o Any subsequent entries for user are ignored.
o The password field for anyone in the netgroup is disabled.
o Users in netgroup are not returned by and thus are not allowed to log in.
o Anyone else can log in with their usual password, shell, and home directory, but with a gecos field of
FILES
Protected password database used when system is converted to trusted system.
Standard password file used by HP-UX.
Shadow password file.
SEE ALSO
chfn(1), chsh(1), finger(1), login(1), passwd(1), pwck(1M), pwconv(1M), useradd(1M), a64l(3C), crypt(3C), getpass(3C), getpwent(3C), get-
prpwent(3), authcap(4), shadow(4), limits(5).
STANDARDS CONFORMANCE
passwd(4)