Administrator's Guide

abcdeux console Mon Mar 12 10:13 - 10:19 (00:06)
root pts/2 Fri Mar 9 13:51 - 15:12 (01:21)
abcdeux console Thu Mar 8 12:21 - 12:22 (00:00)
root pts/ta Wed Mar 7 15:38 - 18:13 (02:34)
The following command lists when reboots have occurred:
# last reboot
reboot system boot Sun Mar 28 18:06 still logged in
reboot system boot Sun Mar 28 17:48 - 18:06 (00:17)
reboot system boot Sun Mar 28 17:40 - 17:48 (00:08)
reboot system boot Thu Feb 19 18:25 - 17:40 (37+23:15)
reboot system boot Mon Feb 16 13:56 - 18:25 (3+04:28)
2.2.3 Checking Who Is Logged In
The who command examines the /etc/utmp file to obtain current user login information.
In addition, the who command can list logins, logoffs, reboots, changes to the system
clock, and processes spawned by the init process.
Use the who -u command to monitor who is currently logged in. For example:
# who -u
aperson console Aug 5 11:28 old 5796 system.home.company.com
aperson pts/0 Aug 17 18:11 0:03 24944 system
aperson pts/1 Aug 5 11:28 1:14 5840 system
See who(1) for more information.
2.3 Authenticating Users with PAM
The Pluggable Authentication Modules (PAM) are an industry-standard framework
providing authentication, account management, session management, and password
services. This section gives an overview of PAM and describes the PAM configuration
files: /etc/pam.conf and /etc/pam_user.conf.
For more information, see pam(3), pam_*(5), pam.conf(4), pam_user.conf(4), and
security(4).
2.3.1 Overview
PAM provides the flexibility to choose any authentication service available on the system.
The PAM framework also enables you to plug in new authentication service modules and
make them available without modifying the applications.
Whenever a user logs in either locally or remotely (for example, using login or rlogin),
the user must be checked or authenticated as a valid user of the system. As authentication
methods improve and change over time, the login services would also have to change.
To avoid constant changing of the login services just to revise the authentication code,
PAM was developed so that different authentication methods can be used without
modifying the login code.
34 Administering User and System Security