Cisco Prime Access Registrar 6.0.1 User Guide

Using LDAP

This chapter provides information about using Lightweight Directory Access Protocol (LDAP) with Cisco Prime Access Registrar (Prime Access Registrar) to access information directories. You can use Prime Access Registrar to authenticate and authorize access requests by querying user information through LDAP.

Note Prime Access Registrar supports LDAP version 3 and LDAP version 2 directory servers.

This chapter contains the following sections:

•Configuring LDAP

•Analyzing LDAP Trace Logs

•Bind-Based Authentication for LDAP

Configuring LDAP

To use LDAP in Prime Access Registrar, use aregcmd to do the following:

1. Configuring the LDAP Service.

2. Configuring an LDAP RemoteServer.

3. Setting LDAP As Authentication and Authorization Service.

4. Saving Your Configuration.

After you issue the save command, Prime Access Registrar attempts to validate the configuration, checks for all required properties, and ensures there is no logic error. If the validation is successful, Prime Access Registrar saves the configuration to the MCD database. When Prime Access Registrar is reloaded, it shuts down any current LDAP connections and builds new connections for the configured LDAP remote servers.

Configuring the LDAP Service

You configure an LDAP service under /Radius/Services. When you define an LDAP service under /Radius/Services, you must set its type to LDAP.

[ //localhost/Radius/Services/AR-LDAP ] 

Name = AR-LDAP

Description = 

Type = ldap

IncomingScript~ = 

OutgoingScript~ = 

OutagePolicy~ = RejectAll

OutageScript~ = 

MultipleServersPolicy = Failover

RemoteServers/

Table 20-1 describes the LDAP service properties.

This section contains the following topics:

•MultipleServersPolicy

•RemoteServers

MultipleServersPolicy

Use the MultipleServersPolicy property to configure the LDAP remote servers in RoundRobin mode, or the default Failover mode applies. When set to Failover, Prime Access Registrar directs requests to the first server in the /Radius/Services/LDAP/RemoteServers list. If that server should fail or go offline, Prime Access Registrar redirects all requests to the next server in the list. The process continues until Prime Access Registrar locates an online server.

When set to RoundRobin, Prime Access Registrar directs each request to the next server in the RemoteServers list to share the resource load across all listed servers.

RemoteServers

Use the RemoteServers directory to list one or more remote servers to process access requests. The servers must also be listed in order under /Radius/RemoteServers.

The order of the RemoteServers list determines the sequence for directing access requests when MultipleServersPolicy is set to RoundRobin mode. The first server in the list receives all access requests when MultipleServersPolicy is set to Failover mode.

Configuring an LDAP RemoteServer

Use the aregcmd command add to add LDAP servers under /Radius/RemoteServers. You must configure an LDAP RemoteServer object for each RemoteServer object you list under /Radius/Services/LDAP/RemoteServers.

The Name, Protocol, Port, HostName, BindName, BindPassword, SearchPath, and Filter properties must be configured to use an LDAP remote server.

The Name, Protocol, Port, HostName, SearchPath, and Filter properties must be configured to enable Bind-Based Authentication.

Note You can leave the BindName, BindPassword, UserPasswordAttribute, PasswordEncryptionStyle and DNSLookupAndLDAPRebindInterval properties blank when you configure the Bind-Based Authentication feature in Prime Access Registrar.

Table 20-2 describes the LDAP Remote Server properties.

This section contains the following topics:

•DNS Look Up and LDAP Rebind Interval

•LDAPToRadiusMappings

•LDAPToEnvironmentMappings

•LDAPToCheckItemMappings

DNS Look Up and LDAP Rebind Interval

Prime Access Registrar provides a DNS Look-up and LDAP Rebind feature that enables you to use a smart DNS server for LDAP hostname resolution, allows you to query a DNS server at set intervals to resolve the LDAP hostname, and optionally rebind to the LDAP server, if necessary.

When you configure Prime Access Registrar to use an LDAP directory server, you can specify the hostname of the LDAP directory server. The hostname can be a qualified or an unqualified name. You can also specify a timeout period after which Prime Access Registrar will again resolve the hostname. If the IP address returned is different from the previous, Prime Access Registrar establishes a new LDAP bind connection.

The DNSLookupAndLDAPRebindInterval property specifies the timeout period after which the Prime Access Registrar server will attempt to resolve the LDAP hostname to IP address (DNS resolution). When you do not modify DNSLookupAndLDAPRebindInterval, the default value zero indicates the server will perform normal connection and binding only at start-up time or during a reload. Unless you change the default to a value greater than zero, the server will not perform periodic DNS lookups.

Prime Access Registrar maintains and uses the existing bind connection until a new one is established to minimize any performance impact during the transfer. Prime Access Registrar ensures that no requests are dropped or lost during the transfer to a new LDAP binding.

Set the DNSLookupAndLDAPRebindInterval using a numerical value and the letter H for hours or M for minutes, such as in the following examples:

set DNSLookupAndLDAPRebindInterval 15M—performs DNS resolution every 15 minutes

Note We recommend that you do not set DNSLookupAndLDAPRebindInterval to a value less than 15 minutes to minimize its effect on server performance.

set DNSLookupAndLDAPRebindInterval   1h—performs DNS resolution every hour

Configure the DNS Look-up and LDAP Rebind

To configure the DNS Look-up and LDAP Rebind,

Step 1 Log into the Prime Access Registrar server, and use aregcmd to navigate to //localhost/Radius/Remoteservers. If necessary, add the LDAP server, or change directory to it.

cd /Radius/RemoteServers/ldap-serv1/

Step 2 Set the DNSLookupAndLDAPRebindInterval property to the interval time desired.

set DNSLookupAndLDAPRebindInterval 30 M

LDAP Rebind Failures

Prime Access Registrar records any name resolution failures, bind successes and failures, and the destination hostname and IP address in the log file. At trace level 3, Prime Access Registrar also logs the time of any new bind connections and the closing of any old bind connections.

If either the name resolution or bind attempt fail, Prime Access Registrar continues using the existing bind connection until the timeout has expired again. If there is no existing bind connection, Prime Access Registrar marks the remote server object as down.

LDAPToRadiusMappings

Configure LDAPToRadiusMappings with a list of name/value pairs where name is the name of the data store attribute to retrieve from the user record and the value is the name of the RADIUS attribute to set to the value of the data store attribute retrieved.

Values stored in a multivalued field in the LDAP directory are mapped to multiple RADIUS attributes, For example, if the LDAPToRadiusMappings has the following entry:

tunnel-info = Cisco-AVPair

The following LDAP fields in the user's record will create four Cisco-AVPair attributes in the user's Access-Accept RADIUS packet:

tunnel-info: vpdn:tunnel-id=ssg001

tunnel-info: vpdn:tunnel-type=12tp

tunnel-info: vpdn:ip-addresses=10.2.2.2

tunnel-info: vpdn:12tp-tunnel-password=secret

LDAPToEnvironmentMappings

LDAPToEnvironmentMappings comprises a list of attribute name/value pairs or AV pairs where the name is the name of the data store attribute to retrieve from the user record, and the value is the name of the Environment variable to set to the value of the LDAP attribute retrieved.

For example, when the LDAPToEnvironmentMappings has the entry: group =User-Group, the RemoteServer retrieves the attribute from the LDAP user entry for the specified user, uses the value returned, and sets the Environment variable User-Group to that value.

LDAPToCheckItemMappings

LDAPToCheckItemMappings comprises a list of LDAP AV pairs which must be present in the RADIUS access request and must match, both name and value, for the check to pass. Prime Access Registrar will first authenticate the user's password in the Access-Request before validating the check item attributes.

Setting LDAP As Authentication and Authorization Service

Use aregcmd to configure the LDAP Service as the default authentication and authorization service under /Radius as in the following:

set DefaultAuthenticationService  AR-LDAP

set DefaultAuthorizationService  AR-LDAP

Saving Your Configuration

When you use aregcmd to save your configuration, Prime Access Registrar does the following:

•Attempts to validate the configuration

•Checks for all required parameters

•Ensures there are no logic errors

If the validation is successful, Prime Access Registrar saves the configuration to the MCD database. When you reload, Prime Access Registrar shuts down any current LDAP connections and builds new connections for the configured LDAP servers.

This section contains the following topics:

•CHAP Interoperability with LDAP

•Allowing Special Characters in LDAP Usernames

•Dynamic LDAP Search Base

CHAP Interoperability with LDAP

If the you plan to use CHAP authentication with an LDAP backing store, the password in LDAP must be stored as clear text. This is due to the one-way hash used by the CHAP, crypt, SHA-1, and SSHA encryption algorithms.

Allowing Special Characters in LDAP Usernames

This feature allows you to use special characters in LDAP usernames. The allowable special characters are *, (,), and \. These special characters can be included in the string passed to LDAP as the LDAP username value (usually the RADIUS username attribute).

The default of EscapeSpecialCharInUserName is FALSE. To enable this feature, use aregcmd to set the EscapeSpecialCharInUserName attribute in /Radius/RemoteServers/ldap-server to TRUE, as shown in the following example.

cd /Radius/RemoteServers/ldap-server

set EscapeSpecialCharInUserName  TRUE

/Radius/RemoteServers/Ldap-Server

EscapeSpecialCharinUserName = TRUE

Note This feature supports the LDAP V3 library.

Dynamic LDAP Search Base

A new environment variable, Dynamic-Search-Path (see rex.h), can be used to set the dynamic LDAP search base. If this environment variable is defined for an LDAP service, it will override the default LDAP search base defined in the LDAP Remote Server configuration. This allows the LDAP search base to be configured on a per-user basis.

For example, you could match the search base to the organization and domain (in a Tcl script called from /Radius/IncomingScript):

set user [ $request get User-Name ]

if { [ regexp {^[^@]+@([^\.]+)\.(.+)$} $user m org domain ] } {

$environ put Dynamic-Search-Path "ou=$org,ou=people,o=$domain"

Analyzing LDAP Trace Logs

Prime Access Registrar records in the log files any name resolution failures, bind successes and failures, and the destination hostname and IP address. At trace level 3, Prime Access Registrar logs the time of any new bind connections and the closure of any old bind connections and also information about user login requests and reply messages.

This section contains the following topics:

•Successful Bind Message

•Bind Failure Messages

•Login Failure Messages

Successful Bind Message

The following message is logged in the name_radius_1_trace file, when the Prime Access Registrar server successfully binds to the LDAP server. In this case, spatula-u5 is the LDAP server listening on port number 389.

10/12/2012 11:02:57: Log: Successfully bind to LDAP Server ldapserver (spatula-u5:389)

Bind Failure Messages

The following messages are logged in the name_radius_1_trace file, when Prime Access Registrar server fails to bind to the LDAP server.

10/12/2012 11:10:50: Log: Write in LDAPClient returned an error (32)

10/12/2012 11:10:50: Log: Remote LDAP Server ldapserver (spatula-u5:387): Unable to 
bind to LDAP Server: Can't contact LDAP server

10/12/2012 11:10:50: Log: Remote LDAP Server ldapserver (spatula-u5:387): Failed to 
open the connection to the LDAP server

Messages like those above could indicate that the hostname specified does not resolve to the correct IP address of the LDAP server or the configured port number might not be the port on which the LDAP server listens.

The following messages are logged in the name_radius_1_trace file, when Prime Access Registrar server fails to bind to the LDAP server.

10/12/2012 11:45:14: Log: Remote LDAP Server ldapserver (spatula-u5:389): Unable to 
bind to LDAP Server: No such object ()

10/12/2012 11:45:14: Log: Remote LDAP Server ldapserver (spatula-u5:389): Failed to 
open the connection to the LDAP server

The Distinguished Name (DN) provided in the BindName property was invalid. The DN provided in the BindName property should contain the exact string used in the directory server to define the object.

The following messages are logged in the name_radius_1_trace file, when Prime Access Registrar server fails to bind to the LDAP server.

10/12/2012 11:51:55: Log: Remote LDAP Server ldapserver (spatula-u5:389): Unable to 
bind to LDAP Server: Invalid credentials

10/12/2012 11:51:55: Log: Remote LDAP Server ldapserver (spatula-u5:389): Failed to 
open the connection to the LDAP server

The messages above indicate that the password provided in the BindPassword property was incorrect.

Login Failure Messages

The following messages are logged in the name_radius_1_trace file, when user jane tries to login. These messages indicate that user jane does not have a record in the directory server or the SearchPath property has an incorrect value. The SearchPath property should have the directory where the user record is stored in the directory server.

Notice how the messages specify the service, remote LDAP server, username, and contents of the Access-Reject packet.

10/12/2012 11:24:17: P8457: Authenticating and Authorizing with Service AR-LDAP

10/12/2012 11:24:17: id = 5

10/12/2012 11:24:17: P8457: Remote LDAP Server ldapserver (spatula-u5: 389): Querying 
LDAP server, id = 5.

10/12/2012 11:24:17: P8457: Remote LDAP Server ldapserver (spatula-u5: 389): GotLDAP 
response, id = 5.

10/12/2012 11:24:17: P8457: Remote LDAP Server ldapserver (spatula-u5: 389): No 
matching entries returned from LDAP query.

10/12/2012 11:24:17: P8457: User jane was not found in the LDAP store

10/12/2012 11:24:17: P8457: Rejecting request

10/12/2012 11:24:17: P8457: Rejecting request

10/12/2012 11:24:17: P8457: Trace of Access-Reject packet

10/12/2012 11:24:17: P8457: identifier = 4

10/12/2012 11:24:17: P8457: length = 35

10/12/2012 11:24:17: P8457: reqauth = 01:ad:cf:c7:4f:8e:a4:38:b0:d8:0a:e5:3d:9f:64:16

10/12/2012 11:24:17: P8457: Reply-Message = Access Denied

The following messages are logged in the name_radius_1_trace file, when user bob tries to login. These messages indicate that user bob tried to login with an incorrect password.

10/12/2012 11:36:59: P8461: Authenticating and Authorizing with Service AR-LDAP

10/12/2012 11:36:59: id = 7

10/12/2012 11:36:59: P8461: Remote LDAP Server ldapserver (spatula-u5: 389): Querying 
LDAP server, id = 7.

10/12/2012 11:36:59: P8461: Remote LDAP Server ldapserver (spatula-u5: 389): Got LDAP 
response, id = 7.

10/12/2012 11:36:59: P8461: Remote Server ldapserver (spatula-u5:389): User bob's 
password does not match

10/12/2012 11:36:59: P8461: User bob's password does not match

10/12/2012 11:36:59: P8461: Rejecting request

10/12/2012 11:36:59: P8461: Rejecting request

10/12/2012 11:36:59: P8461: Trace of Access-Reject packet

10/12/2012 11:36:59: P8461: identifier = 6

10/12/2012 11:36:59: P8461: length = 35

10/12/2012 11:36:59: P8461: reqauth = de:8d:4b:c4:f9:c0:06:a6:98:2d:8c:e9:f3:a9:a3:c2

10/12/2012 11:36:59: P8461: Reply-Message = Access Denied

The following messages are logged in the name_radius_1_trace file, when user bob tries to login. These messages indicate the user record for user bob does not contain an attribute called pass. The UserPasswordAttribute property has an incorrect value called pass. The UserPasswordAttribute property should have the attribute name in the directory records where the user password is stored.

10/12/2012 12:02:09: P9865: Authenticating and Authorizing with Service AR-LDAP

10/12/2012 12:02:09: id = 2

10/12/2012 12:02:09: P9865: Remote LDAP Server ldapserver (spatula-u5: 389): Querying 
LDAP server, id = 2.

10/12/2012 12:02:09: P9865: Remote LDAP Server ldapserver (spatula-u5: 389): Got LDAP 
response, id = 2.

10/12/2012 12:02:09: P9865: Remote LDAP Server ldapserver (spatula-u5: 389): LDAP 
entry for user bob did not have a password (" pass") attribute

10/12/2012 12:02:09: P9865: User bob's password does not match

10/12/2012 12:02:09: P9865: Rejecting request

10/12/2012 12:02:09: P9865: Rejecting request

10/12/2012 12:02:09: P9865: Trace of Access-Reject packet

10/12/2012 12:02:09: P9865: identifier = 10

10/12/2012 12:02:09: P9865: length = 35

10/12/2012 12:02:09: P9865: reqauth = 0d:b6:83:f9:e8:3d:a4:ad:f1:c9:33:72:91:0b:29:1c

10/12/2012 12:02:09: P9865: Reply-Message = Access Denied

Note Remember to reload the Prime Access Registrar server after any changes to the LDAP server configuration.

Bind-Based Authentication for LDAP

Prime Access Registrar supports most of the LDAP servers. But, a few of the LDAP servers do not support the functionality of Prime Access Registrar, which gets the passwords from the LDAP and matches them in Prime Access Registrar.

The bind-based authentication feature in Prime Access Registrar allows you to use any LDAP server; it verifies the password in the LDAP database instead of the Prime Access Registrar databse. When Prime Access Registrar receives a request, it sends the username and password to the LDAP server. The LDAP server searches for a match, and approves the request if it finds a matching user credential in its database. It rejects the request if it does not find any matching credentials.

Configuring Bind-Based Authentication for LDAP

To configure the bind-based authentication for LDAP,

Step 1 Launch aregcmd.

Step 2 Create an LDAP service.

[ //localhost/Radius ]

cd Services/

add ldap

cd ldap

set Type ldap

[ //localhost/Radius/Services/ldap ]

    Name = ldap

    Description =

    Type = ldap

    IncomingScript~ =

    OutgoingScript~ =

    OutagePolicy~ = RejectAll

    OutageScript~ =

    MultipleServersPolicy = Failover

    RemoteServers/

cd RemoteServers

add 1 ldapserver

Step 3 Create the LDAP Remote Server Object.

[ //localhost/Radius ]

cd RemoteServers

add ldapserver

cd ldapserver

[ //localhost/Radius/RemoteServers/ldap ]

set Port <remote ldap server prt numer>

set HostName <remote ldap server name/ipaddress>

set SearchPath <configured in ldap server>

set UseBindBasedAuthentication TRUE

cd /Radius

set DefaultAuthenticationService <ldap service name>

set DefaultAuthorizationService <ldap service name>

Step 4 Save the configuration.

save

Step 5 Restart the application.

reload