HP HPE6-A78 - Aruba Certified Network Security Associate Exam

The AOS Wireless Intrusion Prevention System (WIP) in an AOS-8 architecture (Mobility Controllers or Mobility Master) is designed to detect and mitigate wireless threats, such as rogue APs and unauthorized clients. WIP classifies clients and APs based on their behavior and status in the network.

Authorized Client Definition: In the context of WIP, an "Authorized" client is one that has successfully authenticated to an authorized AP (an AP managed by the MC and part of the company’s network) and is actively passing encrypted traffic. This typically means the client has completed 802.1X authentication (e.g., in a WPA3-Enterprise network) or PSK authentication (e.g., in a WPA3-Personal network) and is communicating securely with the AP.

Option D, "A client that has successfully authenticated to an authorized AP and passed encrypted traffic," is correct. This matches the WIP definition of an Authorized client: the client must authenticate to an AP that is classified as "Authorized" (i.e., part of the company’s network) and must be passing encrypted traffic, indicating a secure connection (e.g., using WPA3 encryption).

Option A, "A client that is on the WIP whitelist," is incorrect. WIP does not use a client whitelist for classification. The AP whitelist is used to authorize APs, not clients. Client classification (e.g., Authorized, Interfering) is based on their authentication status and connection to authorized APs.

Option B, "A client that has a certificate issued by a trusted Certification Authority (CA)," is incorrect. While a certificate might be used for 802.1X authentication (e.g., EAP-TLS), WIP does not classify clients as Authorized based on their certificate status. The classification depends on successful authentication to an authorized AP and encrypted traffic.

Option C, "A client that is NOT on the WIP blacklist," is incorrect. WIP does use blacklisting (e.g., for clients that violate security policies), but being "not on the blacklist" does not make a client Authorized. A client must actively authenticate to an authorized AP and pass encrypted traffic to be classified as Authorized.

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

"In the Wireless Intrusion Prevention (WIP) system, an ‘Authorized’ client is defined as a client that has successfully authenticated to an authorized AP and is passing encrypted traffic. An authorized AP is one that is managed by the Mobility Controller and part of the company’s network. For example, a client that completes 802.1X authentication to an authorized AP using WPA3-Enterprise and sends encrypted traffic is classified as Authorized." (Page 414, WIP Client Classification Section)

Additionally, the HPE Aruba Networking Security Guide notes:

"WIP classifies clients as ‘Authorized’ if they have authenticated to an authorized AP and are passing encrypted traffic, indicating a secure connection. Clients that are not authenticated or are connected to rogue or neighbor APs are classified as ‘Interfering’ or other categories, depending on their behavior." (Page 78, WIP Classifications Section)

To ensure secure transmission of log data over the network, particularly when dealing with sensitive or critical information, using TLS (Transport Layer Security) for encrypted communication between network devices and syslog servers is necessary:

Secure Logging Setup: When configuring an ArubaOS-CX switch to send logs securely to a Syslog server, specifying the server with the TLS option ensures that all transmitted log data is encrypted. Additionally, the switch must have a valid certificate to establish a trusted connection, preventing potential eavesdropping or tampering with the logs in transit.

Other Options:

Option B, Option C, and Option D are less accurate or applicable for directly encrypting log data between the device and Syslog server as specified in the company policies.

Symmetric encryption is a type of encryption where the same key is used to encrypt and decrypt the message. It's called "symmetric" because the key used for encryption is identical to the key used for decryption. The data, or plaintext, is transformed into ciphertext during encryption, and then the same key is used to revert the ciphertext back to plaintext during decryption. It is a straightforward method but requires secure handling and exchange of the encryption key.

WPA3-Enterprise is a security protocol introduced to enhance the security of wireless networks, particularly in enterprise environments. It builds on the foundation of WPA2 but introduces stronger encryption and key management practices. In WPA3-Enterprise, authentication is typically performed using 802.1X, and encryption is handled using the Advanced Encryption Standard (AES).

WPA3-Enterprise Encryption: WPA3-Enterprise uses AES with the Galois/Counter Mode Protocol (GCMP) or Cipher Block Chaining Message Authentication Code Protocol (CCMP), both of which are AES-based encryption methods. WPA3 does not use TKIP (Temporal Key Integrity Protocol), which is a legacy encryption method used in WPA and early WPA2 deployments and is considered insecure.

Pairwise Master Key (PMK): In WPA3-Enterprise, the PMK is derived during the 802.1X authentication process (e.g., via EAP-TLS or EAP-TTLS). Each client authenticates individually with the authentication server (e.g., ClearPass), resulting in a unique PMK for each client. This PMK is then used to derive session keys (Pairwise Transient Keys, PTKs) for encrypting the client’s traffic, ensuring that each client’s traffic is encrypted with unique keys.

Option A, "Traffic is encrypted with TKIP and keys derived from a PMK shared by all clients on the WLAN," is incorrect because WPA3 does not use TKIP (it uses AES), and the PMK is not shared among clients in WPA3-Enterprise; each client has a unique PMK.

Option B, "Traffic is encrypted with TKIP and keys derived from a unique PMK per client," is incorrect because WPA3 does not use TKIP; it uses AES.

Option C, "Traffic is encrypted with AES and keys derived from a PMK shared by all clients on the WLAN," is incorrect because, in WPA3-Enterprise, the PMK is unique per client, not shared.

Option D, "Traffic is encrypted with AES and keys derived from a unique PMK per client," is correct. WPA3-Enterprise uses AES for encryption, and each client derives a unique PMK during 802.1X authentication, which is used to generate unique session keys for encryption.

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

"WPA3-Enterprise enhances security by using AES encryption with GCMP or CCMP. In WPA3-Enterprise mode, each client authenticates via 802.1X, resulting in a unique Pairwise Master Key (PMK) for each client. The PMK is used to derive session keys (Pairwise Transient Keys, PTKs) that encrypt the client’s traffic with AES, ensuring that each client’s traffic is protected with unique keys. WPA3 does not support TKIP, which is a legacy encryption method." (Page 285, WPA3-Enterprise Security Section)

Additionally, the HPE Aruba Networking Wireless Security Guide notes:

"WPA3-Enterprise requires 802.1X authentication, which generates a unique PMK for each client. This PMK is used to derive AES-based session keys, providing individualized encryption for each client’s traffic and eliminating the risks associated with shared keys." (Page 32, WPA3 Security Features Section)

In an HPE Aruba Networking AOS-8 architecture with a Mobility Master (MM), Mobility Controllers (MCs), and campus APs (CAPs), the WLAN is configured to use Tunnel forwarding mode and WPA3-Enterprise security. In Tunnel mode, all user traffic from the APs is encapsulated in a GRE tunnel and sent to the MC, which then forwards the traffic to the appropriate VLAN. The WLAN is assigned to VLAN 301, and the core routing switches act as the default router for wireless user traffic.

Tunnel Forwarding Mode: In this mode, the AP does not directly place user traffic onto the wired network. Instead, the AP tunnels all user traffic to the MC over a GRE tunnel. The MC then decapsulates the traffic and places it onto the wired network in the specified VLAN (VLAN 301 in this case). This means the VLAN tagging for user traffic occurs at the MC, not at the AP.

VLAN 301 Assignment: Since the WLAN is assigned to VLAN 301, the MC will tag user traffic with VLAN 301 when forwarding it to the wired network. The core routing switches, acting as the default router, need to receive this traffic on VLAN 301 to route it appropriately.

Therefore, VLAN 301 needs to be carried on the links between the MC ports and the core routing switches, as this is where the MC forwards the user traffic after decapsulating it from the GRE tunnel.

Option A, "Only links on the path between APs and the core routing switches," is incorrect because, in Tunnel mode, the APs do not directly forward user traffic to the wired network. The traffic is tunneled to the MC, so the links between the APs and the core switches do not need to carry VLAN 301 for user traffic (though they may carry other VLANs for AP management).

Option B, "Only links on the path between APs and the MC," is incorrect for the same reason. The GRE tunnel between the AP and MC carries encapsulated user traffic, and VLAN 301 tagging occurs at the MC, not on the AP-to-MC link.

Option C, "All links in the campus LAN to ensure seamless roaming," is incorrect because VLAN 301 only needs to be present where the MC forwards user traffic to the wired network (i.e., between the MC and the core switches). Extending VLAN 301 to all links is unnecessary and could introduce security or scalability issues.

Option D, "Only links between MC ports and the core routing switches," is correct because the MC places user traffic onto VLAN 301 and forwards it to the core switches, which act as the default router.

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

"In Tunnel forwarding mode, the AP encapsulates all user traffic in a GRE tunnel and sends it to the Mobility Controller (MC). The MC decapsulates the traffic and forwards it to the wired network on the VLAN assigned to the WLAN. For example, if the WLAN is assigned to VLAN 301, the MC tags the user traffic with VLAN 301 and sends it out of its wired interface to the upstream switch. Therefore, the VLAN must be configured on the links between the MC and the upstream switch or router that acts as the default gateway for the VLAN." (Page 275, Tunnel Forwarding Mode Section)

Additionally, the HPE Aruba Networking Wireless LAN Design Guide notes:

"When using Tunnel mode, the VLAN assigned to the WLAN must be carried on the wired links between the Mobility Controller and the default router for the VLAN. The links between the APs and the MC do not need to carry the user VLAN, as all traffic is tunneled to the MC, which handles VLAN tagging." (Page 52, VLAN Configuration Section)

HPE Aruba Networking’s Wireless Intrusion Prevention (WIP) system, part of the AOS-8 architecture (Mobility Master and Mobility Controllers), is designed to detect and classify rogue APs. The "AOS Detected Radios" page provides details about detected APs, including their SSID, BSSID, and match methods used to classify them.

In this case, the AP is classified as a rogue with the following match methods:

Plus one: This indicates that the BSSID of the detected AP is numerically close (e.g., differs by one in the last octet) to the MAC address of a known device in the network.

Eth-Wired-Mac-Table: This indicates that the AP’s MAC address (or a closely related MAC address) was found in the wired network’s MAC address table, suggesting that the AP is connected to the LAN.

These match methods suggest that the AP is likely connected to the company’s wired LAN (via the Eth-Wired-Mac-Table match) and has a BSSID that is close to a known device’s MAC address (Plus one match). Since this AP is not part of the company’s authorized AP list (it’s broadcasting "PublicWiFi," which may not be a corporate SSID), it is classified as a suspected rogue. This scenario is common when an unauthorized AP is plugged into the corporate LAN, posing a security risk.

Option A, "The AP has been detected using multiple MAC addresses," is incorrect because the match methods do not indicate multiple MAC addresses; they indicate a close match to a known MAC and a presence in the wired MAC table.

Option C, "The AP is an AP that belongs to your solution," is incorrect because the AP is classified as a rogue, meaning it is not part of the authorized APs in the solution.

Option D, "The AP has a BSSID that is close to your authorized APs’ BSSIDs," is partially correct in that the "Plus one" match indicates a close BSSID, but the key reason for the rogue classification is its connection to the LAN (Eth-Wired-Mac-Table), not just the BSSID similarity.

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

"The Wireless Intrusion Prevention (WIP) system detects rogue APs by analyzing their BSSIDs, SSIDs, and connectivity to the wired network. The ‘Eth-Wired-Mac-Table’ match method indicates that the AP’s MAC address (or a closely related address) was found in the wired network’s MAC address table, suggesting that the AP is connected to the LAN. The ‘Plus one’ match method indicates that the AP’s BSSID is numerically close to a known MAC address in the network, which can indicate a potential rogue device attempting to mimic a legitimate device." (Page 412, Rogue AP Detection Section)

Additionally, the guide notes:

"A rogue AP is classified as ‘suspected rogue’ if it is detected on the wired network (e.g., via Eth-Wired-Mac-Table) and is not part of the authorized AP list. This often occurs when an unauthorized AP is connected to the corporate LAN." (Page 413, Rogue AP Classification Section)

Given the error message from the ClearPass Policy Manager (CPPM) Event Viewer, indicating a RADIUS authentication attempt from an unknown Network Access Device (NAD), you should check that the IP address the Mobility Controller (MC) is using to communicate with CPPM matches the IP address defined for the MC in the CPPM's device inventory. If there is a mismatch in IP addresses, CPPM will not recognize the MC as a known device and will not process the authentication request, leading to the error observed.

An initialization vector (IV) is a random or pseudo-random value used in encryption algorithms to enhance security. It is commonly used in symmetric encryption modes like Cipher Block Chaining (CBC) or Counter (CTR) modes with algorithms such as AES, which is used in WPA3 and other Aruba security features.

Option B, "It makes encryption algorithms more secure by ensuring that the same plaintext and key can produce different ciphertext," is correct. The primary purpose of an IV is to introduce randomness into the encryption process. When the same plaintext is encrypted with the same key multiple times, the IV ensures that the resulting ciphertext is different each time. This prevents attackers from identifying patterns in the ciphertext, which could otherwise be used to deduce the plaintext or key. For example, in AES-CBC mode, the IV is XORed with the first block of plaintext before encryption, and each subsequent block is chained with the previous ciphertext, ensuring unique outputs.

Option A, "It enables programs to convert easily-remembered passphrases to keys of a correct length," is incorrect. This describes a key derivation function (KDF), such as PBKDF2, which converts a passphrase into a cryptographic key of the correct length. An IV is not involved in key derivation.

Option C, "It helps parties to negotiate the keys and algorithms used to secure data before data transmission," is incorrect. This describes a key exchange or handshake protocol (e.g., Diffie-Hellman or the 4-way handshake in WPA3), not the role of an IV. The IV is used during the encryption process, not during key negotiation.

Option D, "It enables the conversion of asymmetric keys into keys that are suitable for symmetric encryption," is incorrect. This describes a process like hybrid encryption (e.g., using RSA to encrypt a symmetric key), which is not the purpose of an IV. An IV is used in symmetric encryption to enhance security, not to convert keys.

The HPE Aruba Networking Wireless Security Guide states:

"An initialization vector (IV) is a random value used in symmetric encryption algorithms like AES to enhance security. The IV ensures that the same plaintext encrypted with the same key produces different ciphertext each time, preventing attackers from identifying patterns in the ciphertext. In WPA3, for example, the IV is used in AES-GCMP encryption to ensure that each packet is encrypted uniquely, even if the same data is sent multiple times." (Page 28, Encryption Fundamentals Section)

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

"The initialization vector (IV) in encryption algorithms like AES-CBC or AES-GCMP makes encryption more secure by ensuring that identical plaintext encrypted with the same key results in different ciphertext. This randomness prevents pattern analysis attacks, which could otherwise compromise the security of the encryption." (Page 282, Wireless Encryption Section)

To enable managers to use certificates to log into the Web UI of an Aruba Mobility Controller (MC), where Aruba ClearPass Policy Manager (CPPM) acts as the external server for authentication, it is essential to ensure that the MC trusts the HTTPS certificate used by CPPM. This involves uploading a trusted CA certificate to the MC that matches the one used by CPPM. Additionally, configuring a username and password for CPPM on the MC might be necessary to secure and facilitate communication between the MC and CPPM. This setup ensures that certificate-based authentication is securely validated, maintaining secure access control for the Web UI.

The scenario involves troubleshooting an 802.1X authentication issue on HPE Aruba Networking switches (likely AOS-CX switches) that use a cluster of HPE Aruba Networking ClearPass Policy Manager (CPPM) servers as the RADIUS server. The switches show Access-Rejects in their statistics, indicating that CPPM is receiving and processing the authentication requests but rejecting them. However, the records for these Access-Rejects are not visible in CPPM Access Tracker.

Access Tracker: Access Tracker (Monitoring > Live Monitoring > Access Tracker) in CPPM logs all authentication attempts, including successful (Access-Accept) and failed (Access-Reject) requests. If an Access-Reject is not visible in Access Tracker, it suggests that the request was processed at a lower level and not logged in Access Tracker, or there is a visibility issue (e.g., filtering, clustering).

Option A, "Go to the CPPM Event Viewer, because this is where RADIUS Access Rejects are stored," is correct. The Event Viewer (Monitoring > Event Viewer) in CPPM logs system-level events, including RADIUS-related events that might not appear in Access Tracker. For example, if the Access-Reject is due to a configuration issue (e.g., the switch’s IP address is not recognized as a Network Access Device, NAD, or the shared secret is incorrect), the request may be rejected before it is logged in Access Tracker, and the Event Viewer will capture this event (e.g., "RADIUS authentication attempt from unknown NAD"). Since the switches confirm that CPPM is sending Access-Rejects, the Event Viewer is a good place to look for more details.

Option B, "Verify that you are logged in to the CPPM UI with read-write, not read-only, access," is incorrect. Access Tracker visibility is not dependent on read-write vs. read-only access. Both types of accounts can view Access Tracker records, though read-only accounts cannot modify configurations. The issue is that the records are not appearing, not that the user lacks permission to see them.

Option C, "Make sure that CPPM cluster settings are configured to show Access-Rejects," is incorrect. In a CPPM cluster, Access Tracker records are synchronized across nodes, and there is no specific cluster setting to "show Access-Rejects." Access Tracker logs all authentication attempts by default, unless filtered out (e.g., by time range or search criteria), but the issue here is that the records are not appearing at all.

Option D, "Click Edit in Access Viewer and make sure that the correct servers are selected," is incorrect. Access Tracker (not "Access Viewer") does not have an "Edit" option to select servers. In a CPPM cluster, Access Tracker shows records from all nodes by default, and the user can filter by time, NAD, or other criteria, but the absence of records suggests a deeper issue (e.g., the request was rejected before logging in Access Tracker).

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

"If an Access-Reject is not visible in Access Tracker, it may indicate that the RADIUS request was rejected at a low level before being logged. The Event Viewer (Monitoring > Event Viewer) logs system-level events, including RADIUS Access-Rejects that do not appear in Access Tracker. For example, if the request is rejected due to an unknown NAD or shared secret mismatch, the Event Viewer will log an event like ‘RADIUS authentication attempt from unknown NAD,’ providing insight into the rejection." (Page 301, Troubleshooting RADIUS Issues Section)

Additionally, the HPE Aruba Networking AOS-CX 10.12 Security Guide notes:

"When troubleshooting 802.1X authentication issues, if the switch logs show Access-Rejects from the RADIUS server (e.g., ClearPass) but the records are not visible in Access Tracker, check the RADIUS server’s system logs. In ClearPass, the Event Viewer logs RADIUS Access-Rejects that may not appear in Access Tracker, such as those caused by NAD configuration issues." (Page 150, Troubleshooting 802.1X Authentication Section)