HP HPE6-A78 - Aruba Certified Network Security Associate Exam

Control Plane Security (CPsec) enhances security in the network by protecting management traffic between APs and Mobility Controllers (MCs) from eavesdropping. CPsec ensures that all control and management traffic that transits the network is encrypted, thus preventing potential attackers from gaining access to sensitive management data. It helps in securing the network's control plane, which is crucial for maintaining the integrity and privacy of the network operations.

The Lockheed Martin Cyber Kill Chain model describes the stages of a cyber attack. In the exploitation phase, the attacker uses vulnerabilities to gain access to the system. Following this, in the installation phase, the attacker installs a backdoor or other malicious software to ensure persistent access to the compromised system. This backdoor can then be used to control the system, steal data, or execute additional attacks.

Devices use the Diffie-Hellman exchange to agree on a shared secret in a secure manner over an insecure network. The main purpose of this cryptographic protocol is to enable two parties to establish a shared secret over an unsecured communication channel. This shared secret can then be used to encrypt subsequent communications using a symmetric key cipher. The Diffie-Hellman exchange is particularly valuable because it allows the secure exchange of cryptographic keys over a public channel without the need for a prior shared secret. This protocol is a foundational element for many secure communications protocols, including SSL/TLS, which is used to secure connections on the internet. References to the Diffie-Hellman protocol and its uses can be found in standard cryptographic textbooks and documentation such as those from the Internet Engineering Task Force (IETF) and security protocol specifications.

An example of a social engineering attack is described in option A, where an email is used to impersonate a bank and deceive users into entering their bank login information on a counterfeit website. Social engineering attacks exploit human psychology rather than technical hacking techniques to gain access to systems, data, or personal information. These attacks often involve tricking people into breaking normal security procedures. The other options describe different types of technical attacks that do not primarily rely on manipulating individuals through deceptive personal interactions.

The scenario involves an AOS-8 Mobility Controller (MC) with a WLAN where a new user group has been added. Users in this group cannot connect to the WLAN, receiving errors indicating no Internet access and inability to reach resources. Exhibit 1 shows the ClearPass Policy Manager (CPPM) Access Tracker record for one user:

CPPM sends an Access-Accept with the VSA Radius:Aruba:Aruba-User-Role user_group4.

The endpoint is classified as "Known," but the user cannot access resources. Exhibit 2 (not provided but described) shows that the AOS device (MC) assigned the user’s client to the "denyall" role, which likely denies all access, explaining the lack of Internet and resource access.

Analysis:

CPPM sends the Aruba-User-Role VSA with the value "user_group4," indicating that the user should be assigned to the "user_group4" role on the MC.

However, the MC assigns the client to the "denyall" role, which typically denies all traffic, resulting in no Internet or resource access.

The issue lies in why the MC did not apply the "user_group4" role sent by CPPM.

Option A, "The AOS device does not have the correct RADIUS dictionaries installed on it to understand the Aruba-User-Role VSA," is incorrect. If the MC did not have the correct RADIUS dictionaries to understand the Aruba-User-Role VSA, it would not process the VSA at all, and the issue would likely affect all users, not just the new user group. Additionally, Aruba-User-Role is a standard VSA in AOS-8, and the dictionaries are built into the system.

Option B, "The AOS device has a server derivation rule configured on it that has overridden the role sent by CPPM," is incorrect. Server derivation rules on the MC can override roles sent by the RADIUS server (e.g., based on attributes like username or NAS-IP), but there is no indication in the scenario that such a rule is configured. If a derivation rule were overriding the role, it would likely affect more users, and the issue would not be specific to the new user group.

Option C, "The clients rejected the server authentication on their side because they do not have the root CA for CPPM’s RADIUS/EAP certificate," is incorrect. If the clients rejected the server authentication (e.g., due to a missing root CA for CPPM’s certificate), the authentication would fail entirely, and CPPM would not send an Access-Accept with the Aruba-User-Role VSA. The scenario confirms that authentication succeeded (Access-Accept was sent), so this is not the issue.

Option D, "The role name that CPPM is sending does not match the role name configured on the AOS device," is correct. CPPM sends the role "user_group4" in the Aruba-User-Role VSA, but the MC assigns the client to the "denyall" role. This suggests that the role "user_group4" does not exist on the MC, or there is a mismatch in the role name (e.g., due to case sensitivity, typos, or underscores vs. hyphens). In AOS-8, if the role specified in the Aruba-User-Role VSA does not exist on the MC, the MC falls back to a default role, which in this case appears to be "denyall," denying all access. The likely problem is that the role name "user_group4" sent by CPPM does not match the role name configured on the MC (e.g., it might be "user-group4" or a different name).

The HPE Aruba Networking AOS-8 8.11 User Guide states:

"When the Mobility Controller receives an Aruba-User-Role VSA in a RADIUS Access-Accept message, it attempts to assign the specified role to the client. If the role name sent by the RADIUS server (e.g., ‘user_group4’) does not match a role configured on the controller, the controller will fall back to a default role, such as ‘denyall,’ which may deny all access. To resolve this, ensure that the role name sent by the RADIUS server matches the role name configured on the controller, accounting for case sensitivity and naming conventions (e.g., underscores vs. hyphens)." (Page 306, Role Assignment Troubleshooting Section)

Additionally, the HPE Aruba Networking ClearPass Policy Manager 6.11 User Guide notes:

"A common issue when assigning roles via the Aruba-User-Role VSA is a mismatch between the role name sent by ClearPass and the role name configured on the Aruba device. If the role name does not match (e.g., ‘user_group4’ vs. ‘user-group4’), the device will not apply the intended role, and the client may be assigned a default role like ‘denyall,’ resulting in access issues. Verify that the role names match exactly in both ClearPass and the device configuration." (Page 290, RADIUS Role Assignment Issues Section)

A honeypot can be used to launch a Man-in-the-Middle (MITM) attack on wireless clients by examining wireless clients' probe requests and then broadcasting the SSIDs in those probes. Clients with those SSIDs in their preferred network list may then automatically connect to the honeypot, believing it to be a legitimate network. Once the client is connected to the attacker's honeypot, the attacker can intercept, monitor, or manipulate the client's traffic, effectively executing a MITM attack.

When deploying ArubaOS-CX switches that tunnel client traffic to an Aruba Mobility Controller (MC), the licensing requirements typically involve Policy Enforcement Firewall (PEF) licenses. These licenses enable the MC to enforce firewall policies and perform deep packet inspection (DPI). Therefore, for each switch tunneling traffic to the MC, a PEF license would be necessary.

In this scenario, a new HPE Aruba Networking Mobility Controller (MC) and campus APs (CAPs) are deployed, with a WLAN configured for 802.1X authentication using HPE Aruba Networking ClearPass Policy Manager (CPPM) as the RADIUS server. A client test fails, and no record of the authentication attempt appears in ClearPass Access Tracker. However, a ping from the MC to CPPM is successful, confirming basic network connectivity between the MC and CPPM.

The absence of a record in Access Tracker indicates that CPPM did not receive the RADIUS authentication request from the MC, or the request was rejected at a low level before being logged in Access Tracker. Access Tracker typically logs all RADIUS authentication attempts (successful or failed), so the lack of a record suggests a configuration or connectivity issue at the RADIUS level.

Option C, "Check CPPM Event Viewer," is correct. The CPPM Event Viewer logs system-level events, including RADIUS-related errors that might not appear in Access Tracker. For example, if the MC’s IP address is not configured as a Network Access Device (NAD) in CPPM, or if the shared secret between the MC and CPPM does not match, CPPM may reject the RADIUS request before it reaches Access Tracker. The Event Viewer will log such errors (e.g., "RADIUS authentication attempt from unknown NAD"), providing insight into why the request was not processed.

Option A, "Renew CPPM's RADIUS/EAP certificate," is incorrect because the issue is that CPPM did not receive or process the authentication request (no record in Access Tracker). If there were a certificate issue (e.g., an expired or untrusted certificate), the request would still reach CPPM, and Access Tracker would log a failure with a certificate-related error.

Option B, "Check connectivity between CPPM and a backend directory server," is incorrect because the issue occurs before CPPM processes the authentication request. If CPPM cannot contact a backend directory server (e.g., Active Directory), the authentication attempt would still be logged in Access Tracker with a failure reason related to the directory server.

Option D, "Reset the user credentials," is incorrect because the issue is not related to the user’s credentials. The authentication request never reached CPPM, so the credentials were not evaluated.

The HPE Aruba Networking ClearPass Policy Manager 6.11 User Guide states:

"If an authentication attempt does not appear in Access Tracker, it indicates that the RADIUS request was not received by ClearPass or was rejected at a low level before being logged. The Event Viewer (Monitoring > Event Viewer) should be checked for system-level errors, such as ‘RADIUS authentication attempt from unknown NAD’ or shared secret mismatches. For example, if the Network Access Device (NAD) IP address of the Mobility Controller is not configured in ClearPass, or if the shared secret does not match, the request will be dropped, and an error will be logged in the Event Viewer." (Page 301, Troubleshooting RADIUS Issues Section)

Additionally, the HPE Aruba Networking AOS-8 8.11 User Guide notes:

"When troubleshooting 802.1X authentication issues, verify that the Mobility Controller can communicate with the RADIUS server. If a ping is successful but no authentication records appear in the RADIUS server’s logs (e.g., ClearPass Access Tracker), check the RADIUS server’s system logs (e.g., ClearPass Event Viewer) for errors related to NAD configuration or shared secret mismatches." (Page 498, Troubleshooting 802.1X Authentication Section)

The scenario involves an AOS-8 controller-based solution with a WPA3-Enterprise WLAN using HPE Aruba Networking ClearPass Policy Manager (CPPM) for authentication. The company is using digital certificates for authentication (likely EAP-TLS, as it’s the most common certificate-based method for WPA3-Enterprise). A user’s Windows domain computer has certificates installed, but authentication fails. The Mobility Controller (MC) logs show Access-Rejects from CPPM, indicating that CPPM rejected the authentication attempt.

Access-Reject: An Access-Reject message from CPPM means that the authentication failed due to a policy violation, certificate issue, or other configuration mismatch. To troubleshoot, we need to find detailed information about why CPPM rejected the request.

Option C, "The Alerts tab in the authentication record in CPPM Access Tracker," is correct. Access Tracker in CPPM logs all authentication attempts, including successful and failed ones. For a failed attempt (Access-Reject), the authentication record in Access Tracker will include an Alerts tab that provides detailed reasons for the failure. For example, if the client’s certificate is invalid (e.g., expired, not trusted, or missing a required attribute), or if the user does not match a policy in CPPM, the Alerts tab will specify the exact issue (e.g., "Certificate not trusted," "User not found in directory").

Option A, "The reports generated by HPE Aruba Networking ClearPass Insight," is incorrect. ClearPass Insight is used for generating reports and analytics (e.g., trends, usage patterns), not for real-time troubleshooting of specific authentication failures.

Option B, "The RADIUS events within the CPPM Event Viewer," is incorrect. The Event Viewer logs system-level events (e.g., service crashes, NAD mismatches), not detailed authentication failure reasons. While it might log that an Access-Reject was sent, it won’t provide the specific reason for the rejection.

Option D, "The packets captured on the MC control plane destined to UDP 1812," is incorrect. Capturing packets on the MC control plane for UDP 1812 (RADIUS authentication port) can show the RADIUS exchange, but it won’t provide the detailed reason for the Access-Reject. The MC logs already show the Access-Reject, so the issue lies on the CPPM side, and Access Tracker provides more insight.

The HPE Aruba Networking ClearPass Policy Manager 6.11 User Guide states:

"Access Tracker (Monitoring > Live Monitoring > Access Tracker) logs all authentication attempts, including failed ones. For an Access-Reject, the authentication record in Access Tracker includes an Alerts tab that provides detailed reasons for the failure. For example, in a certificate-based authentication (e.g., EAP-TLS), the Alerts tab might show ‘Certificate not trusted’ if the client’s certificate is not trusted by ClearPass, or ‘User not found’ if the user does not match a policy. This is the primary place to look for deeper insight into authentication failures." (Page 299, Access Tracker Troubleshooting Section)

Additionally, the HPE Aruba Networking AOS-8 8.11 User Guide notes:

"If the Mobility Controller logs show an Access-Reject from the RADIUS server (e.g., ClearPass), check the RADIUS server’s authentication logs for details. In ClearPass, the Access Tracker provides detailed failure reasons in the Alerts tab of the authentication record, such as certificate issues or policy mismatches." (Page 500, Troubleshooting 802.1X Authentication Section)

When troubleshooting connectivity issues for a user connecting to an AP managed by a standalone Mobility Controller (MC) in an AOS-8 architecture, detailed logs and debugs specific to the user’s client are essential. The MC provides several tools for capturing logs and debugging information, including packet captures and user-specific debug logs.

Option D, "In the MC UI’s Diagnostics > Logs pages, add a ‘user-debug’ log setting for the client's MAC address," is correct. The "user-debug" feature in the MC allows administrators to enable detailed debugging for a specific client by specifying the client’s MAC address. This generates logs related to the client’s authentication, association, role assignment, and other activities, which are critical for troubleshooting connectivity issues. The Diagnostics > Logs pages in the MC UI provide a user-friendly way to configure this setting and view the resulting logs.

Option A, "In the MC CLI, set up a control plane packet capture and filter for the client's IP address," is incorrect because control plane packet captures are used to capture management traffic (e.g., between the MC and APs or other controllers), not user traffic. Additionally, the client may not yet have an IP address if connectivity is failing, making an IP-based filter less effective.

Option B, "In the MC CLI, set up a data plane packet capture and filter for the client's MAC address," is a valid troubleshooting method but is not the best choice for getting detailed logs. Data plane packet captures are useful for analyzing user traffic (e.g., to see if packets are being dropped), but they do not provide the same level of detailed logging as the "user-debug" feature, which includes authentication and association events.

Option C, "In the MC UI’s Traffic Analytics dashboard, look for the client's IP address," is incorrect because the Traffic Analytics dashboard is used for monitoring application usage and traffic patterns, not for detailed troubleshooting of a specific client’s connectivity issues. Additionally, if the client cannot connect, it may not have an IP address or generate traffic visible in the dashboard.

The HPE Aruba Networking AOS-8 8.11 User Guide states:

"To troubleshoot issues for a specific wireless client, you can enable user-specific debugging using the ‘user-debug’ feature. In the Mobility Controller UI, navigate to Diagnostics > Logs, and add a ‘user-debug’ log setting for the client’s MAC address. This will generate detailed logs for the client, including authentication, association, and role assignment events, which can be viewed in the Logs page. For example, to enable user-debug for a client with MAC address 00:11:22:33:44:55, add the setting ‘user-debug 00:11:22:33:44:55’." (Page 512, Troubleshooting Wireless Clients Section)

Additionally, the guide notes:

"While packet captures (control plane or data plane) can be useful for analyzing traffic, the ‘user-debug’ feature provides more detailed logs for troubleshooting client-specific issues, such as failed authentication or association problems." (Page 513, Debugging Tools Section)