users in shadow file explanation
this article explain the /etc/shadow
this file content the users information
example of the user data
n1x:$6$UoDmVdoW$tYQQm5uHgOpeEKPygIaQ1GM/0IBbdYVrLHu8ZYF5pT17D3VM.FFKa2wS8J6gqbGKC2IpgImXy7SYVJK9r/fdw.:16631:7:15:2:14:16819:
username -> n1x
password -> $6$UoDmVdoW$tYQQm5uHgOpeEKPygIaQ1GM/0IBbdYVrLHu8ZYF5pT17D3VM.FFKa2wS8J6gqbGKC2IpgImXy7SYVJK9r/fdw.
last date password update since 1970-1-1 -> 16631
you can calculate it simply in python
>>> from datetime import timedelta,datetime >>> s = '1970-01-01' >>> x = datetime.strptime(s,"%Y-%m-%d") >>> x + timedelta(days=16631) datetime.datetime(2015, 7, 15, 0, 0)
minmum password age -> 7
maximum password age -> 15
warning days -> 2
inactive days -> 14
expiration date -> 16819
we can list or modify a user by a chage command
example
[root@localhost ~]# chage -m 7 -M 15 -W 2 -I 14 -E 2016-01-19 n1x [root@localhost ~]# chage -l n1x Last password change : Jul 15, 2015 Password expires : Jul 30, 2015 Password inactive : Aug 13, 2015 Account expires : Jan 19, 2016 Minimum number of days between password change : 7 Maximum number of days between password change : 15 Number of days of warning before password expires : 2 [root@localhost ~]#
for setting default config for all users you can use /etc/login.defs
# Password aging controls:
#
# PASS_MAX_DAYS Maximum number of days a password may be used.
# PASS_MIN_DAYS Minimum number of days allowed between password changes.
# PASS_MIN_LEN Minimum acceptable password length.
# PASS_WARN_AGE Number of days warning given before a password expires.
#
PASS_MAX_DAYS 30
PASS_MIN_DAYS 10
PASS_MIN_LEN 10
PASS_WARN_AGE 1
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