Chapter 3 Controlling Access to Systems (Tasks)

This chapter describes the procedures for controlling who can access Solaris systems. The following is a list of the information in this chapter.

• Controlling System Access (Task Map)

• Securing Logins and Passwords (Task Map)

• Changing the Password Algorithm (Task Map)

• Monitoring and Restricting Superuser (Task Map)

• SPARC: Controlling Access to System Hardware (Task Map)

For overview information about system security, see Chapter 2, Managing Machine Security (Overview).

Controlling System Access (Task Map)

A computer is as secure as its weakest point of entry. The following task map shows the areas that you should monitor and secure.

Securing Logins and Passwords (Task Map)

The following task map points to procedures that monitor user logins and that disable user logins.

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

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. 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 must be specified in a comma-separated list.

   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 name 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 rimmer
rimmer       500     staff           10   Annalee J. Rimmer
                     /export/home/rimmer
                     /bin/sh
                     PS 010103 10 7 -1

rimmer

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).

Annalee J. Rimmer

Identifies the comment.

/export/home/rimmer

Identifies the user's home directory.

/bin/sh

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

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. 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 name 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.

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. Create the /etc/nologin file in a text editor.

   # vi /etc/nologin

3. Include a message about system availability.

4. 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 GNOME login attempt.

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. Create the loginlog file in the /var/adm directory.

   # touch /var/adm/loginlog

3. Set read-and-write permissions for root user on the loginlog file.

   # chmod 600 /var/adm/loginlog

4. Change group membership to sys on the loginlog file.

   # chgrp sys /var/adm/loginlog

5. 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 2003 jdoe:/dev/pts/2:Tue Nov 4 10:21:21 2003 jdoe:/dev/pts/2:Tue Nov 4 10:21:30 2003 jdoe:/dev/pts/2:Tue Nov 4 10:21:40 2003 jdoe:/dev/pts/2:Tue Nov 4 10:21:49 2003 #

   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.

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. 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 … SYSLOG_FAILED_LOGINS=0 #

3. 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

4. Edit the syslog.conf file to log failed password attempts.

   The failures should be sent 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 configuration information for the syslog daemon.

      # svcadm refresh system/system-log

5. Verify that the log works.

   For example, as an ordinary user, log in to the system with the wrong password. Then, in the Primary Administrator role or 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 #

6. 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

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.

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. 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

3. Create an /etc/d_passwd file that contains the login programs that you are requiring to have a dial-up password.

   Include shell programs that a user could be running at login, for example, uucico, sh, ksh, 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:

   Later in the procedure, you are going to add the encrypted password for each login program.

4. Set ownership to root on the two files.

   # chown root /etc/dialups /etc/d_passwd

5. Set group ownership to root on the two files.

   # chgrp root /etc/dialups /etc/d_passwd

6. Set read-and-write permissions for root on the two files.

   # chmod 600 /etc/dialups /etc/d_passwd

7. 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. Capture the encrypted password.

      # grep username /etc/shadow > username.temp

   4. 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:

   5. Delete the temporary user.

      # userdel username

8. 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.

9. 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

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. Put the following single-line entry into the /etc/d_passwd file:

   /usr/bin/sh:*:

Changing the Password Algorithm (Task Map)

The following task map points to procedures to administer password algorithms.

Changing the Default Algorithm for Password Encryption

By default, user passwords are encrypted with the crypt_unix algorithm. You can use a stronger encryption algorithm, such as MD5 or Blowfish, by changing the default password encryption algorithm.

How to Specify an Algorithm for Password Encryption

In this procedure, the BSD-Linux version of the MD5 algorithm is the default encryption algorithm that is used when users change their passwords. This algorithm is suitable for a mixed network of machines that run the Solaris, BSD, and Linux versions of UNIX. For a list of password encryption algorithms and algorithm identifiers, see Table 2–1.

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. Specify the identifier for your chosen encryption algorithm.

   Type the identifier as the value for the CRYPT_DEFAULT variable in the /etc/security/policy.conf file.

   You might want to comment the file to explain your choice.

   # cat /etc/security/policy.conf … CRYPT_ALGORITHMS_ALLOW=1,2a,md5,5,6 # # Use the version of MD5 that works with Linux and BSD systems. # Passwords previously encrypted with __unix__ will be encrypted with MD5 # when users change their passwords. # # CRYPT_DEFAULT=__unix__ CRYPT_DEFAULT=1

   In this example, the algorithms configuration ensures that the weakest algorithm, crypt_unix, is never used to encrypt a password. Users whose passwords were encrypted with the crypt_unix module get a crypt_bsdmd5-encrypted password when they change their passwords.

   For more information on configuring the algorithm choices, see the policy.conf(4) man page.

Example 3–6 Using the Blowfish Algorithm for Password Encryption

In this example, the identifier for the Blowfish algorithm, 2a, is specified as the value for the CRYPT_DEFAULT variable in the policy.conf file:

CRYPT_ALGORITHMS_ALLOW=1,2a,md5,5,6
#CRYPT_ALGORITHMS_DEPRECATE=__unix__
CRYPT_DEFAULT=2a

This configuration is compatible with BSD systems that use the Blowfish algorithm.

How to Specify a New Password Algorithm for an NIS Domain

When users in an NIS domain change their passwords, the NIS client consults its local algorithms configuration in the /etc/security/policy.conf file. The NIS client machine encrypts the password.

1. Specify the password encryption algorithm in the /etc/security/policy.conf file on the NIS client.

2. Copy the modified /etc/security/policy.conf file to every client machine in the NIS domain.

3. To minimize confusion, copy the modified /etc/security/policy.conf file to the NIS root server and to the slave servers.

How to Specify a New Password Algorithm for an NIS+ Domain

When users in an NIS+ domain change their passwords, the NIS+ name service consults the algorithms configuration in the /etc/security/policy.conf file on the NIS+ master. The NIS+ master, which is running the rpc.nispasswd daemon, creates the encrypted password.

1. Specify the password encryption algorithm in the /etc/security/policy.conf file on the NIS+ master.

2. To minimize confusion, copy the NIS+ master's /etc/security/policy.conf file to every host in the NIS+ domain.

How to Specify a New Password Algorithm for an LDAP Domain

When the LDAP client is properly configured, the LDAP client can use the new password algorithms. The LDAP client behaves just as an NIS client behaves.

1. Specify a password encryption algorithm in the /etc/security/policy.conf file on the LDAP client.

2. Copy the modified policy.conf file to every client machine in the LDAP domain.

3. Ensure that the client's /etc/pam.conf file does not use a pam_ldap module.

   Ensure that a comment sign (#) precedes entries that include pam_ldap.so.1. Also, do not use the new server_policy option with the pam_authtok_store.so.1 module.

   The PAM entries in the client's pam.conf file enable the password to be encrypted according to the local algorithms configuration. The PAM entries also enable the password to be authenticated.

   When users in the LDAP domain change their passwords, the LDAP client consults its local algorithms configuration in the /etc/security/policy.conf file. The LDAP client machine encrypts the password. Then, the client sends the encrypted password, with a {crypt} tag, to the server. The tag tells the server that the password is already encrypted. The password is then stored, as is, on the server. For authentication, the client retrieves the stored password from the server. The client then compares the stored password with the encrypted version that the client has just generated from the user's typed password.

   ---

   Note –

   To take advantage of password policy controls on the LDAP server, use the server_policy option with the pam_authtok_store entries in the pam.conf file. Passwords are then encrypted on the server by using the Sun Java^TM System Directory Server's cryptographic mechanism. For the procedure, see Chapter 11, Setting Up Sun Java System Directory Server With LDAP Clients (Tasks), in System Administration Guide: Naming and Directory Services (DNS, NIS, and LDAP).

   ---

How to Install a Password Encryption Module From a Third Party

A third-party password encryption algorithm is typically delivered as a module in a software package. When you run the pkgadd command, scripts from the vendor should modify the /etc/security/crypt.conf file. You then modify the /etc/security/policy.conf file to include the new module and its identifier.

1. Add the software by using the pkgadd command.

   For detailed instructions on how to add software, see Adding or Removing a Software Package (pkgadd) in System Administration Guide: Basic Administration.

2. Confirm that the new module and module identifier have been added.

   Read the list of encryption algorithms in the /etc/security/crypt.conf file.

   For example, the following lines show that a module that implements the crypt_rot13 algorithm has been installed.

   # crypt.conf # md5 /usr/lib/security/$ISA/crypt_md5.so rot13 /usr/lib/security/$ISA/crypt_rot13.so # For *BSD - Linux compatibility # 1 is MD5, 2a is Blowfish 1 /usr/lib/security/$ISA/crypt_bsdmd5.so 2a /usr/lib/security/$ISA/crypt_bsdbf.so

3. Add the identifier of the newly installed algorithm to the /etc/security/policy.conf file.

   The following lines show excerpts from the policy.conf file that would need to be modified to add the rot13 identifier.

   # Copyright 1999-2002 Sun Microsystems, Inc. All rights reserved. # ... #ident "@(#)policy.conf 1.12 08/05/14 SMI" # ... # crypt(3c) Algorithms Configuration CRYPT_ALGORITHMS_ALLOW=1,2a,md5,5,6,,rot13 #CRYPT_ALGORITHMS_DEPRECATE=__unix__ CRYPT_DEFAULT=md5

   In this example, the rot13 algorithm is used if the current password was encrypted with the crypt_rot13 algorithm. New user passwords are encrypted with the crypt_sunmd5 algorithm. This algorithm configuration works on Solaris-only networks.

Monitoring and Restricting Superuser (Task Map)

The following task map describes how to monitor and restrict the root user login.

Monitoring and Restricting Superuser

An alternative to using the superuser account is to set up role-based access control. Role-based access control is called RBAC. For overview information on RBAC, see Role-Based Access Control (Overview). To set up RBAC, see Chapter 9, Using Role-Based Access Control (Tasks).

How to Monitor Who Is Using the su Command

The sulog file lists every use of the su command, not only the su attempts that are used to switch from user to superuser.

1. Monitor the contents of the /var/adm/sulog file on a regular basis.

   # more /var/adm/sulog SU 12/20 16:26 + pts/0 stacey-root SU 12/21 10:59 + pts/0 stacey-root SU 01/12 11:11 + pts/0 root-rimmer SU 01/12 14:56 + pts/0 pmorph-root SU 01/12 14:57 + pts/0 pmorph-root

   The entries display the following information:

   • The date and time that the command was entered.

   • If the attempt was successful. A plus sign (+) indicates a successful attempt. A minus sign (-) indicates an unsuccessful attempt.

   • The port from which the command was issued.

   • The name of the user and the name of the switched identity.

   The su logging in this file is enabled by default through the following entry in the /etc/default/su file:

   SULOG=/var/adm/sulog

Troubleshooting

Entries that include ??? indicate that the controlling terminal for the su command cannot be identified. Typically, system invocations of the su command before the desktop appears include ???, as in SU 10/10 08:08 + ??? root-root. After the user starts a desktop session, the ttynam command returns the value of the controlling terminal to the sulog: SU 10/10 10:10 + pts/3 jdoe-root.

Entries similar to the following can indicate that the su command was not invoked on the command line: SU 10/10 10:20 + ??? root-oracle. The user might have switched to the oracle role by using a GUI.

How to Restrict and Monitor Superuser Logins

This method immediately detects superuser attempts to access the local system.

1. View the CONSOLE entry in the /etc/default/login file.

   CONSOLE=/dev/console

   By default, the console device is set to /dev/console. With this setting, root can log in to the console. root cannot log in remotely.

2. Verify that root cannot log in remotely.

   From a remote system, try to log in as superuser.

   mach2 % rlogin -l root mach1 Password: <Type root password of mach1> Not on system console Connection closed.

3. Monitor attempts to become superuser.

   By default, attempts to become superuser are printed to the console by the SYSLOG utility.

   1. Open a terminal console on your desktop.

   2. In another window, use the su command to become superuser.

      % su - Password: <Type root password> #

      A message is printed on the terminal console.

      Sep 7 13:22:57 mach1 su: 'su root' succeeded for jdoe on /dev/pts/6

Example 3–7 Logging Superuser Access Attempts

In this example, superuser attempts are not being logged by SYSLOG. Therefore, the administrator is logging those attempts by removing the comment from the #CONSOLE=/dev/console entry in the /etc/default/su file.

# CONSOLE determines whether attempts to su to root should be logged
# to the named device
#
CONSOLE=/dev/console

When a user attempts to become superuser, the attempt is printed on the terminal console.

SU 09/07 16:38 + pts/8 jdoe-root

Troubleshooting

To become superuser from a remote system when the /etc/default/login file contains the default CONSOLE entry, users must first log in with their user name. After logging in with their user name, users then can use the su command to become superuser.

If the console displays an entry similar to Mar 16 16:20:36 mach1 login: ROOT LOGIN /dev/pts/14 FROM mach2.Example.COM, then the system is permitting remote root logins. To prevent remote superuser access, change the #CONSOLE=/dev/console entry to CONSOLE=/dev/console in the /etc/default/login file.

SPARC: Controlling Access to System Hardware (Task Map)

The following task map describes how to protect the PROM from unwanted access.

Controlling Access to System Hardware

You can protect the physical machine by requiring a password to gain access to the hardware settings. You can also protect the machine by preventing a user from using the abort sequence to leave the windowing system.

How to Require a Password for Hardware Access

On an x86 system, the equivalent to protecting the PROM is to protect the BIOS. Refer to your machine's manuals for how to protect the BIOS.

1. Become superuser or assume a role that includes the Device Security profile, the Maintenance and Repair profile, or the System Administrator profile.

   The System Administrator profile includes the Maintenance and Repair profile. To create a role that includes the System Administrator profile and to assign the role to a user, see Configuring RBAC (Task Map).

2. In a terminal window, type the PROM security mode.

   # eeprom security-mode=command Changing PROM password: New password: <Type password> Retype new password: <Retype password>

   Choose the value command or full. For more details, see the eeprom(1M) man page.

   If, when you type the preceding command, you are not prompted for a PROM password, the system already has a PROM password.

3. (Optional) To change the PROM password, type the following command:

   # eeprom security-password= Press Return Changing PROM password: New password: <Type password> Retype new password: <Retype password>

   The new PROM security mode and password are in effect immediately. However, they are most likely to be noticed at the next boot.

   ---

   Caution –

   Do not forget the PROM password. The hardware is unusable without this password.

   ---

How to Disable a System's Abort Sequence

Some server systems have a key switch. When the key switch is set in the secure position, the switch overrides the software keyboard abort settings. So, any changes that you make with the following procedure might not be implemented.

1. Assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. Change the value of KEYBOARD_ABORT to disable.

   Comment out the enable line in the /etc/default/kbd file. Then, add a disable line:

   # cat /etc/default/kbd … # KEYBOARD_ABORT affects the default behavior of the keyboard abort # sequence, see kbd(1) for details. The default value is "enable". # The optional value is "disable". Any other value is ignored. … #KEYBOARD_ABORT=enable KEYBOARD_ABORT=disable

3. Update the keyboard defaults.

   # kbd -i