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System Administration Guide: Network Services

Chapter 19 Setting Up PPP Authentication (Tasks)

This chapter contains tasks for setting up PPP authentication. Subjects that are covered include the following:

The procedures show how to implement authentication over a dial-up link because dial-up links are more likely to be configured for authentication than leased-line links. You can configure authentication over leased lines if authentication is required by your corporate security policy. For leased-line authentication, use the tasks in this chapter as guidelines.

If you want to use PPP authentication but are not sure which protocol to use, review the section Why Use PPP Authentication?. More detailed information about PPP authentication is in the pppd(1M) man page and in Authenticating Callers on a Link.

Configuring PPP Authentication (Task Map)

This section contains task maps to help you quickly access procedures for PPP authentication.

Table 19–1 Task Map for General PPP Authentication

Task 

Description 

For Instructions 

Configure PAP authentication 

Use these procedures to enable PAP authentication on a dial-in server and a dial-out machine. 

Setting Up PAP Authentication (Task Maps)

Configure CHAP authentication 

Use these procedures to enable CHAP authentication on a dial-in server and a dial-out machine. 

Setting Up CHAP Authentication (Task Maps)

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:

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)

Task 

Description 

For Instructions 

1. Gather preconfiguration information 

Collect user names and other data that is needed for authentication. 

Planning for Authentication on a Link

2. Update the password database, if necessary 

Ensure that all potential callers are in the server's password database. 

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

3. Create the PAP database 

Create security credentials for all prospective callers in /etc/ppp/pap-secrets.

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

4. Modify the PPP configuration files 

Add options specific to PAP to the /etc/ppp/options and /etc/ppp/peers/peer-name files.

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

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

Task 

Description 

For Instructions 

1. Gather preconfiguration information 

Collect user names and other data that is needed for authentication. 

Planning for Authentication on a Link

2. Create the PAP database for the trusted caller's machine 

Create the security credentials for the trusted caller and, if necessary, security credentials for other users who call the dial-out machine, in /etc/ppp/pap-secrets.

How to Configure PAP Authentication Credentials for the Trusted Callers

3. Modify the PPP configuration files 

Add options specific to PAP to the /etc/ppp/options and /etc/ppp/peers/peer-name files.

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

Configuring PAP Authentication on the Dial-in Server

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

ProcedureHow 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.

    Solaris PPP 4.0 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)

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

ProcedureHow 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:

ProcedureHow 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.

    Solaris PPP 4.0 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.

See Also

The following list provides references to related information.

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.

ProcedureHow 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.

Configuring CHAP Authentication

The tasks in this section explain how to implement authentication on a PPP link by using the Challenge-Handshake Authentication Protocol (CHAP). The tasks use the example that is shown in Figure 16–4 to illustrate a working CHAP scenario for dialing up a private network. Use the instructions as the basis for implementing CHAP authentication at your site.

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

Setting Up CHAP Authentication (Task Maps)

Table 19–4 Task Map for CHAP Authentication (Dial-in Server)

Task 

Description 

For Instructions 

1. Assign CHAP secrets to all trusted callers 

Create, or have the callers create, their CHAP secrets. 

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

2. Create the chap-secrets database 

Add the security credentials for all trusted callers to the /etc/ppp/chap-secrets file.

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

3. Modify the PPP configuration files 

Add options specific to CHAP to the /etc/ppp/options and /etc/ppp/peers/peer-name files.

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

Table 19–5 Task Map for CHAP Authentication (Dial-out Machine)

Task 

Description 

For Instructions 

1. Create the CHAP database for the trusted caller's machine 

Create the security credentials for the trusted caller and, if necessary, security credentials for other users who call the dial-out machine, in /etc/ppp/chap-secrets.

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

2. Modify the PPP configuration files 

Add options specific to CHAP to the /etc/ppp/options file.

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

Configuring CHAP Authentication on the Dial-in Server

The first task in setting up CHAP authentication is modifying the /etc/ppp/chap-secrets file. This file contains the CHAP security credentials, including the CHAP secret, that are used to authenticate callers on the link.

Note –

UNIX or PAM authentication mechanisms do not work with CHAP. For example, you cannot use the PPP login option as described in How to Create a PAP Credentials Database (Dial-in Server). If your authentication scenario requires PAM or UNIX-style authentication, choose PAP instead.

The next procedure implements CHAP authentication for a dial-in server in a private network. The PPP link is the only connection to the outside world. The only callers who can access the network have been granted permission by managers of the network, possibly including the system administrator.

ProcedureHow to Create a CHAP Credentials Database (Dial-in Server)

  1. Assemble a list that contains the user names of all trusted callers.

    Trusted callers include all people who have been granted permission to call the private network.

  2. Assign each user a CHAP secret.

    Note –

    Be sure to choose a good CHAP secret that is not easily guessed. No other restrictions are placed on the CHAP secret's contents.

    The method for assigning CHAP secrets depends on your site's security policy. Either you have the responsibility for creating the secrets, or the callers must create their own secrets. If you are not responsible for CHAP secret assignment, be sure to get the CHAP secrets that were created by, or for, each trusted caller.

  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. Modify the /etc/ppp/chap-secrets file.

    Solaris PPP 4.0 includes an /etc/ppp/chap-secrets file that contains helpful comments but no options. You can add the following options for the server CallServe at the end of the existing /etc/ppp/chap-secrets file.


    account1  CallServe   key123   *
account2  CallServe   key456   *

    key123 is the CHAP secret for trusted caller account1.

    key456 is the CHAP secret for trusted caller account2.

See Also

The following list provides references to related information.

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

The task in this section explains how to update existing PPP configuration files to support CHAP authentication on the dial-in server.

ProcedureHow to Add CHAP Support to the PPP Configuration Files (Dial-in Server)

  1. Log in to the dial-in server as superuser.

  2. Modify the /etc/ppp/options file.

    Add the options that are shown in bold for CHAP support.


    # cat /etc/ppp/options
lock
nodefaultroute
name CallServe
auth
    name CallServe

    Defines CallServe as the CHAP name of the user on the local machine, in this instance the dial-in server

    auth

    Makes the local machine authenticate callers before establishing the link

  3. Create the remaining PPP configuration files to support the trusted callers.

    See How to Configure Users of the Dial-in Server and How to Define Communications Over the Serial Line (Dial-in Server).

See Also

To configure CHAP authentication credentials for trusted callers, refer to How to Create a CHAP Credentials Database (Dial-in Server).

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

This section contains tasks for setting up CHAP authentication on the dial-out machines of trusted callers. Depending on your site's security policy, either you or the trusted callers might be responsible for setting up CHAP authentication.

For remote callers to configure CHAP, ensure that the callers' local CHAP secrets match the callers' equivalent CHAP secrets in the dial-in server's /etc/ppp/chap-secrets file. Then give the callers the tasks in this section for configuring CHAP.

Configuring CHAP for trusted callers involves two tasks:

ProcedureHow to Configure CHAP Authentication Credentials for the Trusted Callers

This procedure shows how to set up CHAP credentials for two trusted callers. The steps in the procedure assume that you, the system administrator, are creating the CHAP 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 CHAP configuration in Example of a Configuration Using CHAP Authentication, assume that the dial-out machine belongs to trusted caller account1.

  2. Modify the chap-secrets database for caller account1.

    Solaris PPP 4.0 includes an /etc/ppp/chap-secrets file that has helpful comments but no options. You can add the following options to the existing /etc/ppp/chap-secrets file.


    account1  CallServe   key123   *

    CallServe is the name for the peer that account1 is trying to reach. key123 is the CHAP secret to be used for links between account1 and CallServer.

  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.

    Assume that this machine belongs to caller account2.

  4. Modify the /etc/ppp/chap-secrets database for caller account2.


    account2  CallServe   key456   *

    Now, account2 has secret key456 as its CHAP credentials for use over links to peer CallServe.

See Also

The following list provides references to related information.

Adding CHAP to the Configuration Files (Dial-out Machine)

To learn more about CHAP authentication, refer to Challenge-Handshake Authentication Protocol (CHAP). The next task configures the dial-out machine that belongs to caller account1, which is introduced in Example of a Configuration Using CHAP Authentication.

ProcedureHow to Add CHAP Support to the PPP Configuration Files (Dial-out Machine)

  1. Log in to the dial-out machine as superuser.

  2. Ensure that the /etc/ppp/options file has the following options.


    # cat /etc/ppp/options
lock
nodefaultroute

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


    # cat /etc/ppp/peers/CallServe
/dev/cua/a
57600
noipdefault
defaultroute
idle 120
user account1
connect "chat -U 'mypassword' -f /etc/ppp/mychat"

    The option user account1 sets account1 as the CHAP user name to be given to CallServe. For a description of the other options in the previous file, see the similar /etc/ppp/peers/myserver file in How to Define the Connection With an Individual Peer.

See Also

To test CHAP authentication by calling the dial-in server, refer to How to Call the Dial-in Server.