Configuring PAP Authentication

The tasks in this section explain how to implement authentication on a PPP link by using the Password Authentication Protocol (PAP). The tasks use the example that is shown in Examples of PPP Authentication Configurations to illustrate a working PAP scenario for a dial-up link. Use the instructions as the basis for implementing PAP authentication at your site.

Before you perform the next procedures, you must have done the following:

• Set up and tested the dial-up link between the dial-in server and dial-out machines that belong to trusted callers

• Ideally, for dial-in server authentication, obtained superuser permission for the machine where the network password database is administered, for example, in LDAP, NIS, or local files

• Obtained superuser authority for the local machine, either dial-in server or dial-out machine

Setting Up PAP Authentication (Task Maps)

Use the next task maps to quickly access PAP-related tasks for the dial-in server and trusted callers on dial-out machines.

Table 19-2 Task Map for PAP Authentication (Dial-in Server)

Table 19-3 Task Map for PAP Authentication (Dial-out Machine)

Configuring PAP Authentication on the Dial-in Server

To set up PAP authentication, you must do the following:

• Create a PAP credentials database

• Modify PPP configuration files for PAP support

How to Create a PAP Credentials Database (Dial-in Server)

This procedure modifies the /etc/ppp/pap-secrets file, which contains the PAP security credentials that are used to authenticate callers on the link. /etc/ppp/pap-secrets must exist on both machines on a PPP link.

The sample PAP configuration that was introduced in Figure 16-3 uses the login option of PAP. If you plan to use this option, you might also need to update your network's password database. For more information about the login option, refer to Using the login Option With /etc/ppp/pap-secrets.

1. Assemble a list of all potential trusted callers. Trusted callers are people to be granted permission to call the dial-in server from their remote machines.
2. Verify that each trusted caller already has a UNIX user name and password in the dial-in server's password database.

   ---

   Note - Verification is particularly important for the sample PAP configuration, which uses the login option of PAP to authenticate callers. If you choose not to implement login for PAP, the callers' PAP user names do not have to correspond with their UNIX user names. For information about standard /etc/ppp/pap-secrets, refer to /etc/ppp/pap-secrets File.

   ---

   Do the following if a potential trusted caller does not have a UNIX user name and password:

   1. Confirm with their managers that callers whom you do not know personally have permission to access the dial-in server.
   2. Create UNIX user names and passwords for these callers in the manner that is directed by your corporate security policy.
3. Become superuser on the dial-in server or assume an equivalent role.

   Roles contain authorizations and privileged commands. For more information about roles, see Configuring RBAC (Task Map) in System Administration Guide: Security Services.

4. Edit the /etc/ppp/pap-secrets file.

   This release provides a pap-secrets file in /etc/ppp that contains comments about how to use PAP authentication but no options. You can add the following options at the end of the comments.

   user1 myserver "" *
   user2 myserver "" *
   myserver user2 serverpass *

   To use the login option of /etc/ppp/pap-secrets, you must type the UNIX user name of each trusted caller. Wherever a set of double quotes (““) appears in the third field, the password for the caller is looked up in the server's password database.

   The entry myserver * serverpass * contains the PAP user name and password for the dial-in server. In Figure 16-3, the trusted caller user2 requires authentication from remote peers. Therefore, myserver's /etc/ppp/pap-secrets file contains PAP credentials for use when a link is established with user2.

See Also

The following list provides references to related information.

• Modifying the PPP Configuration Files for PAP (Dial-in Server)

• Configuring PAP Authentication for Trusted Callers (Dial-out Machines)

Modifying the PPP Configuration Files for PAP (Dial-in Server)

The tasks in this section explain how to update any existing PPP configuration files to support PAP authentication on the dial-in server.

How to Add PAP Support to the PPP Configuration Files (Dial-in Server)

The procedure uses as examples the PPP configuration files that were introduced in How to Define Communications Over the Serial Line (Dial-in Server).

1. Log in as superuser on the dial-in server or assume an equivalent role.

   Roles contain authorizations and privileged commands. For more information about roles, see Configuring RBAC (Task Map) in System Administration Guide: Security Services.

2. Add authentication options to the /etc/ppp/options file.

   For example, you would add the options in bold to an existing /etc/ppp/options file to implement PAP authentication:

   lock
   auth
   login
   nodefaultroute
   proxyarp
   ms-dns 10.0.0.1
   idle 120

   auth

   Specifies that the server must authenticate callers before establishing the link.

   login

   Specifies that the remote caller be authenticated by using the standard UNIX user authentication services.

   nodefaultroute

   Indicates that no pppd session on the local system can establish a default route without root privileges.

   proxyarp

   Adds an entry to the system's Address Resolution Protocol (ARP) table that specifies the IP address of the peer and the Ethernet address of the system. With this option the peer appears to be on the local Ethernet to other systems.

   ms-dns 10.0.0.1

   Enables pppd to supply a Domain Name Server (DNS) address, 10.0.0.1, for the client

   idle 120

   Specifies that idle users are disconnected after two minutes.

3. In the /etc/ppp/options.cua.a file, add the following address for the cua/a user.

   :10.0.0.2

4. In the /etc/ppp/options.cua.b file, add the following address for the cua/b user.

   :10.0.0.3

5. In the /etc/ppp/pap-secrets file, add the following entry.

   * * "" *

   ---

   Note - The login option, as previously described, supplies the necessary user authentication. This entry in the /etc/ppp/pap-secrets file is the standard way of enabling PAP with the login option.

   ---

See Also

To configure PAP authentication credentials for trusted callers of the dial-in server, refer to Configuring PAP Authentication for Trusted Callers (Dial-out Machines).

Configuring PAP Authentication for Trusted Callers (Dial-out Machines)

This section contains tasks for setting up PAP authentication on the dial-out machines of trusted callers. As system administrator, you can set up PAP authentication on the systems before distribution to prospective callers. Or, if the remote callers already have their machines, you can give these callers the tasks in this section.

Configuring PAP for trusted callers involves two tasks:

• Configuring the callers' PAP security credentials

• Configuring the callers' dial-out machines to support PAP authentication

How to Configure PAP Authentication Credentials for the Trusted Callers

This procedure shows how to set up PAP credentials for two trusted callers, one of which requires authentication credentials from remote peers. The steps in the procedure assume that you, the system administrator, are creating the PAP credentials on the trusted callers' dial-out machines.

1. Become superuser on a dial-out machine or assume an equivalent role.

   Roles contain authorizations and privileged commands. For more information about roles, see Configuring RBAC (Task Map) in System Administration Guide: Security Services.

   Using the sample PAP configuration that was introduced in Figure 16-3, assume that the dial-out machine belongs to user1.

2. Modify the pap-secrets database for the caller.

   This release provides an /etc/ppp/pap-secrets file that contains helpful comments but no options. You can add the following options to this /etc/ppp/pap-secrets file.

   user1 myserver pass1 *

   Note that user1's password pass1 is passed in readable ASCII form over the link. myserver is caller user1's name for the peer.

3. Become superuser on another dial-out machine or assume an equivalent role.

   Roles contain authorizations and privileged commands. For more information about roles, see Configuring RBAC (Task Map) in System Administration Guide: Security Services.

   Using the PAP authentication example, assume that this dial-out machine belongs to the caller user2.

4. Modify the pap-secrets database for the caller.

   You can add the next options to the end of the existing /etc/ppp/pap-secrets file.

   user2 myserver pass2 *
   myserver user2 serverpass *

   In this example, /etc/ppp/pap-secrets has two entries. The first entry contains the PAP security credentials that user2 passes to dial-in server myserver for authentication.

   user2 requires PAP credentials from the dial-in server as part of link negotiation. Therefore, the /etc/ppp/pap-secrets also contains PAP credentials that are expected from myserver on the second line.

   ---

   Note - Because most ISPs do not supply authentication credentials, the previous scenario might be unrealistic for communications with an ISP.

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See Also

The following list provides references to related information.

• How to Create a PAP Credentials Database (Dial-in Server)

• How to Configure PAP Authentication Credentials for the Trusted Callers

Modifying PPP Configuration Files for PAP (Dial-out Machine)

The following tasks explain how to update existing PPP configuration files to support PAP authentication on the dial-out machines of trusted callers.

The procedure uses the following parameters to configure PAP authentication on the dial-out machine that belongs to user2, who was introduced in Figure 16-3. user2 requires incoming callers to authenticate, including calls from dial-in myserver.

How to Add PAP Support to the PPP Configuration Files (Dial-out Machine)

This procedure uses as examples the PPP configuration files that were introduced in How to Define Communications Over the Serial Line. The procedure configures the dial-out machine that belongs to user2, as shown in Figure 16-3.

1. Log in to the dial-out machine as superuser.
2. Modify the /etc/ppp/options file.

   The next /etc/ppp/options file contains options for PAP support, which are shown in bold.

   # cat /etc/ppp/options
   lock
   name user2
   auth
   require-pap

   name user2

   Sets user2 as the PAP name of the user on the local machine. If the login option is used, the PAP name must be the same as the user's UNIX user name in the password database.

   auth

   States that the dial-out machine must authenticate callers before establishing the link.

   ---

   Note - This dial-out machine demands authentication from its peers, even though most dial-out machines do not make this demand. Either way is acceptable.

   ---

   require-pap

   Demands PAP credentials from the peer.

3. Create an /etc/ppp/peers/peer-name file for the remote machine myserver.

   The next example shows how to add PAP support to the existing /etc/ppp/peers/myserver file that was created in How to Define the Connection With an Individual Peer.

   # cat /etc/ppp/peers/myserver
   /dev/cua/a
   57600
   noipdefault
   defaultroute
   idle 120
   user user2
   remotename myserver
   connect "chat -U 'mypassword' -f /etc/ppp/mychat"

   The new options in bold add PAP requirements for peer myserver.

   user user2

   Defines user2 as the user name of the local machine

   remotename myserver

   Defines myserver as a peer that requires authentication credentials from the local machine

See Also

The following list provides references to related information.

• To test the PAP authentication setup by calling the dial-in server, see How to Call the Dial-in Server.

• To learn more about PAP authentication, see Password Authentication Protocol (PAP).