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Updated:July 15, 2020
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This document describes how to enable Microsoft Lightweight Directory Access Protocol (LDAP) External Authentication with Cisco Firepower Management Center (FMC) and Firepower Threat Defense (FTD).
Cisco recommends that you have knowledge of these topics
Cisco Firepower Threat Defense (FTD)
Cisco Firepower Management Center (FMC)
Microsoft Lightweight Directory Access Protocol (LDAP)
Firepower Threat Defense 6.5.0-123
Firepower Management Center 6.5.0-115
Microsoft Server 2012
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.
The FMC and managed devices include a default admin account for management access. You can add custom user accounts on the Firepower Management Center and on managed devices, either as internal users or, if supported for your model, as external users on an LDAP or RADIUS server. External user authentication is supported for Firepower Management Center and Firepower Threat Defense.
• Internal user - The FMC/FTD device checks a local database for user authentication.
• External user - If the user is not present in the local database, the system information from an external LDAP or RADIUS authentication server to populate its user database.
1. Basic LDAP Configuration in FMC GUI
Step 1. Navigate to System >> Users >> External Authentication:
Step 4.Enable the External Authentication Object and Save:
2. Shell Access for External Users
The FMC supports two different internal admin users: one for the web interface, and another with CLI access. This means there is a clear distinction between who can access the GUI and who can also access CLI. At the time of install, the password for the default admin user is synchronized to be the same on both GUI and CLI, however, they are tracked by different internal mechanisms, and can eventually be different.
LDAP External users must also be granted shell access.
Step 1. Navigate to System >> Users >> External Authentication >> Click on Shell Authentication drop-down box as seen in the image and save:
Step 2. Deploy changes in FMC.
Once shell access for external users is configured, log in via SSH is enabled as seen in the image:
3. External Authentication to FTD
External authentication can be enabled on FTD
Step 1. Navigate to Devices >> Platform Settings >> External Authentication >> Select Enabled and save:
4. User Roles
User privileges are based on the assigned user role. You can also create custom user roles with access privileges tailored to your organization’s needs or you can use predefined roles such as Security Analyst and Discovery Admin.
There are two types of user roles:
Web Interface User Roles
CLI User Roles
For a full list of predefined roles and more information: User Roles
In order to configure a default user role for all External Authentication Objects navigate to System >> Users >> External Authentication >> Select Default User Role: Choose the default user role you would like to assign and select Save.
In order to choose a default user role or assign specific roles to specific users in a certain object group, you can select the object and navigate to Group Controlled Access Roles as seen in the image:
5. SSL or TLS
DNS needs to be configured in the FMC, This is because the Subject value of the Certificate must match the Authentication Object Primary Server Hostname. Once Secure LDAP is configured, packet captures no longer show clear text bind requests.
•SSL changes the default port to 636, TLS keeps it as 389
Note: TLS encryption requires a certificate on all platforms. For SSL, the FTD also requires a certificate. For other platforms, SSL does not require a certificate. However, it is recommended that you always upload a certificate for SSL to prevent man-in-the-middle attacks.
Step 1. Navigate to Devices >> Platform Settings >> External Authentication >> External authentication object and enter the Advanced Options SSL/TLS information:
Step 2. Upload the certificate of the CA who signed the server's certificate. The certificate must be in PEM format.
Step 3. Save the configuration.
1. Test Search Base
Open a Windows command prompt or PowerShell where LDAP is configured and type the command:
dsquery user -name <known username>
PS C:\Users\Administrator> dsquery user -name harry* PS C:\Users\Administrator> dsquery user -name *
2. Test LDAP Integration
Navigate to System >> Users >> External Authentication >> External Authentication Object. At the bottom of the page, there is an Additional Test Parameters section as seen in the image:
Select Test to see results.
1. How do FMC/FTD and LDAP Interact to Download Users?
In order for FMC to be able to pull users from a Microsoft LDAP server, the FMC must first send a bindRequest on port 389 or 636 (SSL) with the LDAP administrator credentials. Once the LDAP server is able to authenticate FMC, it responds with a success message. Finally, FMC is able to make a request with the searchRequest message as described in the diagram:
Notice that the authentication sends passwords in the clear by default:
2. How do FMC/FTD and LDAP Interact to Authenticate a User Login Request?
In order for a user to be able to log in to FMC or FTD while LDAP authentication is enabled, the initial login request is sent to the Firepower, however the username and password are forwarded to LDAP for a success/deny response. This means that FMC and FTD do not keep password information locally in the database and instead await confirmation from LDAP on how to proceed.
If the username and password are accepted, an entry is added in the web GUI as seen in the image:
Run the command show user in FMC CLISH to verify user information:
> show user <username>
The command displays detailed configuration information for the specified user(s). The following values are displayed:
Login — the login name
UID — the numeric user ID Auth (Local or Remote) — how the user is authenticated Access (Basic or Config) — the user's privilege level Enabled (Enabled or Disabled) — whether the user is active Reset (Yes or No) — whether the user must change password at next login Exp (Never or a number) — the number of days until the user's password must be changed Warn (N/A or a number) — the number of days a user is given to change their password before it expires Str (Yes or No) — whether the user's password must meet strength checking criteria Lock (Yes or No) — whether the user's account has been locked due to too many login failures Max (N/A or a number) — the maximum number of failed logins before the user's account is locked
3. SSL or TLS does not work as expected
If you don't enable DNS on the FTDs, you can see errors in the pigtail log that suggest that LDAP is unreachable:
root@SEC-FMC:/$ sudo cd /var/common root@SEC-FMC:/var/common$ sudo pigtail
MSGS: 03-05 14:35:31 SEC-FTD sshd: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=192.0.2.15 user=h.potter MSGS: 03-05 14:35:31 SEC-FTD sshd: pam_ldap: ldap_starttls_s: Can't contact LDAP server MSGS: 03-05 14:35:33 SEC-FTD sshd: error: PAM: Authentication failure for h.potter from 192.0.2.15 MSGS: 03-05 14:35:33 SEC-FTD sshd: Failed keyboard-interactive/pam for h.potter from 192.0.2.15 port 61491 ssh2 MSGS: 03-05 14:35:33 SEC-FTD sshd: error: maximum authentication attempts exceeded for h.potter from 192.0.2.15 port 61491 ssh2 [preauth] MSGS: 03-05 14:35:33 SEC-FTD sshd: Disconnecting authenticating user h.potter 192.0.2.15 port 61491: Too many authentication failures [preauth]
Ensure that Firepower is able to resolve the LDAP Servers FQDN. If not, add the correct DNS as seen in the image:
FTD: Access the FTD CLISH and run the command:
> configure network dns servers <IP Address>
FMC: Choose System > Configuration, and then choose Management Interfaces as seen in the image:
Ensure the certificate uploaded to FMC is the certificate of the CA who signed the LDAP server's certificate, as illustrated in the image below:
Use packet captures in order to confirm LDAP server sends the correct information: