Securing Logins and Passwords

You can limit remote logins and require users to have passwords. You can also monitor failed access attempts and disable logins temporarily.

How to Display a User's Login Status

Become an administrator with the required security attributes.
For more information, see How to Obtain Administrative Rights.
Display a user's login status by using the logins command.
```
# logins -x -l username
```
-x

Displays an extended set of login status information.

-l username

Displays the login status for the specified user. The variable username is a user's login name. Multiple login names are separated by commas.

The logins command uses the appropriate password database to obtain a user's login status. The database can be the local /etc/passwd file, or a password database for the naming service. For more information, see the logins(1M) man page.

Example 3-1 Displaying a User's Login Status

In the following example, the login status for the user rimmer is displayed.

# logins -x -l jdoe
jdoe       500     staff           10   Jaylee Jaye Doe
                   /home/jdoe
                   /bin/bash
                   PS 010103 10 7 -1

jdoe

Identifies the user's login name.

500

Identifies the user ID (UID).

staff

Identifies the user's primary group.

10

Identifies the group ID (GID).

Jaylee Jaye Doe

Identifies the comment.

/home/jdoe

Identifies the user's home directory.

/bin/bash

Identifies the login shell.

PS 010170 10 7 -1

Specifies the password aging information:

Last date that the password was changed
Number of days that are required between changes
Number of days before a change is required
Warning period

How to Display Users Without Passwords

Become an administrator with the required security attributes.
For more information, see How to Obtain Administrative Rights.
Display all users who have no passwords by using the logins command.
```
# logins -p
```
The -p option displays a list of users with no passwords. The logins command uses the password database from the local system unless a naming service is enabled.

Example 3-2 Displaying Users Without Passwords

In the following example, the user pmorph does not have a password.

# logins -p
pmorph          501     other           1       Polly Morph
#

How to Temporarily Disable User Logins

Temporarily disable user logins during system shutdown or routine maintenance. Superuser logins are not affected. For more information, see the nologin(4) man page.

Become an administrator with the required security attributes.
For more information, see How to Obtain Administrative Rights.
Create the /etc/nologin file in a text editor.
```
# vi /etc/nologin
```
Include a message about system availability.
Close and save the file.

Example 3-3 Disabling User Logins

In this example, users are notified of system unavailability.

# vi /etc/nologin
(Add system message here)
 
# cat /etc/nologin 
***No logins permitted.***

***The system will be unavailable until 12 noon.***

You can also bring the system to run level 0, single-user mode, to disable logins. For information on bringing the system to single-user mode, see Chapter 10, Shutting Down a System (Tasks), in System Administration Guide: Basic Administration.

How to Monitor Failed Login Attempts

This procedure captures failed login attempts from terminal windows. This procedure does not capture failed logins from a desktop login attempt.

Become an administrator with the required security attributes.
For more information, see How to Obtain Administrative Rights.
Create the loginlog file in the /var/adm directory.
```
# touch /var/adm/loginlog
```
Set read-and-write permissions for root user on the loginlog file.
```
# chmod 600 /var/adm/loginlog
```
Change group membership to sys on the loginlog file.
```
# chgrp sys /var/adm/loginlog
```
Verify that the log works.
For example, log in to the system five times with the wrong password. Then, display the /var/adm/loginlog file.
```
# more /var/adm/loginlog
jdoe:/dev/pts/2:Tue Nov  4 10:21:10 2010
jdoe:/dev/pts/2:Tue Nov  4 10:21:21 2010
jdoe:/dev/pts/2:Tue Nov  4 10:21:30 2010
jdoe:/dev/pts/2:Tue Nov  4 10:21:40 2010
jdoe:/dev/pts/2:Tue Nov  4 10:21:49 2010
#
```
The loginlog file contains one entry for each failed attempt. Each entry contains the user's login name, tty device, and time of the failed attempt. If a person makes fewer than five unsuccessful attempts, no failed attempts are logged.
A growing loginlog file can indicate an attempt to break into the computer system. Therefore, check and clear the contents of this file regularly. For more information, see the loginlog(4) man page.

How to Monitor All Failed Login Attempts

This procedure captures in a syslog file all failed login attempts.

Become an administrator with the required security attributes.
For more information, see How to Obtain Administrative Rights.

Set up the /etc/default/login file with the desired values for SYSLOG and SYSLOG_FAILED_LOGINS

Edit the /etc/default/login file to change the entry. Make sure that SYSLOG=YES is uncommented.

# grep SYSLOG /etc/default/login
# SYSLOG determines whether the syslog(3) LOG_AUTH facility should be used
SYSLOG=YES
# The SYSLOG_FAILED_LOGINS variable is used to determine how many failed
#SYSLOG_FAILED_LOGINS=5
SYSLOG_FAILED_LOGINS=0
#

Create a file with the correct permissions to hold the logging information.
1. Create the authlog file in the /var/adm directory.
```
# touch /var/adm/authlog
```
2. Set read-and-write permissions for root user on the authlog file.
```
# chmod 600 /var/adm/authlog
```
3. Change group membership to sys on the authlog file.
```
# chgrp sys /var/adm/authlog
```
Edit the syslog.conf file to log failed password attempts.
Send the failures to the authlog file.
1. Type the following entry into the syslog.conf file.
  Fields on the same line in syslog.conf are separated by tabs.
```
auth.notice <Press Tab>  /var/adm/authlog
```
2. Refresh the system-log service.
```
# svcadm refresh system/system-log
```
Verify that the log works.
For example, as an ordinary user, log in to the system with the wrong password. Then, as superuser, display the /var/adm/authlog file.
```
# more /var/adm/authlog
Nov  4 14:46:11 example1 login: [ID 143248 auth.notice] 
 Login failure on /dev/pts/8 from example2, stacey
#
```
Monitor the /var/adm/authlog file on a regular basis.

Example 3-4 Logging Access Attempts After Three Login Failures

Follow the preceding procedure, except set the value of SYSLOG_FAILED_LOGINS to 3 in the /etc/default/login file.

Example 3-5 Closing Connection After Three Login Failures

Uncomment the RETRIES entry in the /etc/default/login file, then set the value of RETRIES to 3. Your edits take effect immediately. After three login retries in one session, the system closes the connection.

How to Create a Dial-Up Password

Caution - When you first establish a dial-up password, be sure to remain logged in to at least one port. Test the password on a different port. If you log off to test the new password, you might not be able to log back in. If you are still logged in to another port, you can go back and fix your mistake.

Become an administrator with the required security attributes.
For more information, see How to Obtain Administrative Rights.
Create an /etc/dialups file that contains a list of serial devices.
Include all the ports that are being protected with dial-up passwords. The /etc/dialups file should appear similar to the following:
```
/dev/term/a
/dev/term/b
/dev/term/c
```
Create an /etc/d_passwd file that contains the login programs that must have a dial-up password.
Include shell programs that a user could be running at login, for example, uucico, sh, ksh, bash, and csh. The /etc/d_passwd file should appear similar to the following:
```
/usr/lib/uucp/uucico:encrypted-password:
/usr/bin/csh:encrypted-password:
/usr/bin/ksh:encrypted-password:
/usr/bin/sh:encrypted-password:
/usr/bin/bash:encrypted-password:
```
Later in the procedure, you are going to add the encrypted password for each login program.
Set ownership to root on the two files.
```
# chown root /etc/dialups /etc/d_passwd
```
Set group ownership to root on the two files.
```
# chgrp root /etc/dialups /etc/d_passwd
```
Set read-and-write permissions for root on the two files.
```
# chmod 600 /etc/dialups /etc/d_passwd
```
Create the encrypted passwords.
1. Create a temporary user.
```
# useradd username
```
2. Create a password for the temporary user.
```
# passwd username
New Password:  <Type password>
Re-enter new Password:   <Retype password>
passwd: password successfully changed for username
```
3. Record the password in a secure location.
4. Capture the encrypted password.
```
# grep username /etc/shadow > username.temp
```
5. Edit the username.temp file.
  Delete all fields except the encrypted password. The second field holds the encrypted password.
  For example, in the following line, the encrypted password is U9gp9SyA/JlSk.
```
temp:U9gp9SyA/JlSk:7967:::::7988:
```
6. Delete the temporary user.
```
# userdel username
```
Copy the encrypted password from username.temp file into the /etc/d_passwd file.
You can create a different password for each login shell. Alternatively, use the same password for each login shell.
Inform your dial-up users of the password.
You should ensure that your means of informing the users cannot be tampered with.

How to Temporarily Disable Dial-Up Logins

Become an administrator with the required security attributes.
For more information, see How to Obtain Administrative Rights.
Put the following single-line entry into the /etc/d_passwd file:
```
/usr/bin/sh:*:
```

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	System Administration Guide: Security Services Oracle Solaris 11 Express 11/10