The following example shows the output of the logins command, which is used with no arguments:

castle% su
Password:
# logins
root             0     other             1     Super-User
smtp             0     root              0     Mail Daemon User
daemon           1     other             1
bin              2     bin               2
sys              3     sys               3
adm              4     adm               4     Admin
uucp             5     uucp              5     uucp Admin
nuucp            9     nuucp             9     uucp Admin
listen          37     adm               4     Network Admin
lp              71     lp                8     Line Printer Admin
winsor        1001     staff            10
ray           1002     staff            10
des           1003     staff            10
rob           1004     staff            10
nobody       60001     nobody        60001     Nobody
noaccess     60002     noaccess      60002     No Access User
nobody4      65534     nogroup       65534     SunOS 4.x Nobody
#

The following example displays an extended set of login status information for user winsor.

# logins -x -l winsor
winsor          1001  staff        10
                 /export/home/winsor
                 /bin/csh
                 PS 000000 -1 -1 -1
#

The following example shows a list of user accounts with no password.

# logins -p
ray        1002    staff    10
des        1003    staff    10
rob        1004    staff    10
#

The following example shows extended login status for all user accounts on a standalone system.

#logins -xu
winsor     1001    staff    10
            /export/home/winsor
            /bin/csh
            PS 000000 -1 -1 -1
ray        1002    staff    10
            /export/home/ray
            /bin/csh
            NP 000000 -1 -1 -1
des        1003  staff      10
            /export/home/des
            /bin/csh
            NP 000000 -1 -1 -1
rob        1004  staff      10
            /export/home/rob
            /bin/csh
            NP 000000 -1 -1 -1
nobody     60001  nobody       60001  Nobody
            /
            /sbin/sh
            LK 082587 -1 -1 -1
noaccess   60002  noaccess     60002  No Access User
            /
            /sbin/sh
            LK 082587 -1 -1 -1
nobody4    65534   nogroup     65534  SunOS 4.x Nobody
            /
            /sbin/sh
            LK 082587 -1 -1 -1
#

Temporarily Disabling User Logins

You can temporarily disable logins to prevent new login sessions in one of two ways:

•  Bringing the system to run level 0 (single-user mode)

•  Creating an /etc/nologin file

When a system will not be available for an extended time, you can create an /etc/nologin file to prevent users from logging in to the system. When a user logs in to a system that has an /etc/nologin file, the message in the /etc/nologin file is displayed and the user login is terminated. Superuser logins are not affected by the /etc/nologin file.

Use the following steps to create an /etc/nologin file:

1.  Become superuser.

2.  Use any editor to create a file named /etc/nologin.

3.  Type the message that will be displayed to users when they log in to the system. If possible, include specific information about when logins will be permitted or how users can find out when they will be able to access the system again.

4.  Save the changes and close the file.

The following example shows the text of a nologin file:

#cat /etc/nologin
No Logins Are Currently Permitted

The system will be unavailable until 12 noon on Friday, October 24.
#

Saving Failed Login Attempts

If it is important for you to track whether users are trying to log in to your user accounts, you can create a /var/adm/loginlog file with read and write permissions for root only. After you create the loginlog file, all failed login activity is written to this file automatically after five failed attempts. The five-try limit avoids recording failed attempts that are the result of typographical errors.

The loginlog file contains one entry for each failed attempt. Each entry contains the user's login name, tty device, and time of the attempt.

---

NOTE:  The loginlog file may grow quickly. To use the information in this file and prevent it from getting too large, check and clear its contents regularly. If this file shows a lot of activity, it may suggest that someone is trying to break into the computer system. If you regularly track information from the loginlog file, consider creating a cron entry to track and clear out the loginlog file.

---

Use the following steps to create a loginlog file:

1.  Become superuser.

2.  Type touch /var/adm/loginlog and press Return.

3.  Type chmod 700 /var/adm/loginlog and press Return.

4.  Type chgrp sys /var/adm/loginlog and press Return.

5.  Make sure the log works by trying to log in to the system six times with the wrong password.

6.  Type more /var/adm/loginlog and review the output to make sure the login attempts are being logged successfully.

Sharing Files

A network server can control which files are available for sharing. It can also control which clients have access to the files and what type of access is permitted to those clients. In general, the file server can grant read/write or read-only access either to all clients or to specific clients. Access control is specified when resources are made available by using the share command.

A server can use the /etc/dfs/dfstab file to list the file systems it makes available to clients on the network. See the Solaris System Administrator's Guide for more information about sharing files (see bibliography at the end of this book).