HPE6-A84 Aruba Certified Network Security Expert Written Exam Questions and Answers

Auto-site clustering is a feature that allows gateways in the same site and group to form a cluster automatically. However, this mode does not support VRRP IP addresses, which are required for dynamic authorization (CoA) from ClearPass Policy Manager (CPPM) to the gateways. Dynamic authorization is a mechanism that allows CPPM to change the attributes or status of a client session on the gateways without requiring re-authentication. This is useful for applying policies, roles, or bandwidth limits based on various conditions. Without VRRP IP addresses, CPPM would not be able to send CoA messages to the correct gateway in case of a failover event, resulting in inconsistent or incorrect client behavior.

To enable VRRP IP addresses for dynamic authorization, you need to set up gateway clusters manually and assign a VRRP VLAN and a VRRP IP address to each cluster. This way, CPPM can use the VRRP IP address as the NAS IP address for RADIUS communications and CoA messages. The VRRP IP address will remain the same even if the active gateway in the cluster changes due to a failover event, ensuring seamless operations. You can find more information about how to set up gateway clusters manually and configure VRRP IP addresses in the Gateway Cluster Deployment - Aruba page and the ClearPass Policy Manager User Guide1.

To configure CPPM to collect information from Intune on demand during the authentication process, you need to use the Intune extension for ClearPass. This extension allows ClearPass to query Intune for device compliance and configuration information using the Intune API. To use this extension, you need to register an app in Azure AD and grant it the required permissions to access Intune1

The Intune extension uses the device ID as the key to query Intune for device information. The device ID is a unique identifier that is assigned by Intune to each enrolled device. The device ID can be obtained from the client certificate that is used for EAP-TLS authentication. Therefore, the certificates issued to clients must include the Intune ID in the subject name, so that ClearPass can extract it and use it to query Intune2

The certificates issued to clients do not need to be issued by a well-known, trusted CA, as long as ClearPass trusts the CA that issued them. The certificates do not need to include the client MAC address in the subject name, as this is not relevant for querying Intune. The certificates do not need to be issued by a ClearPass Onboard CA, as this is not a requirement for using the Intune extension.

An authentication source is a configuration element in CPPM that defines how to connect to an external identity provider and retrieve user or device information . CPPM supports various types of authentication sources, such as Active Directory, LDAP, SQL, Kerberos, and HTTP .

To authenticate wireless and wired clients to Azure AD, you need to set up an authentication source as HTTP type, referencing Azure AD’s FQDN . This type of authentication source allows CPPM to use REST API calls to communicate with Azure AD and validate the user or device credentials . You also need to configure the OAuth 2.0 settings for the authentication source, such as the client ID, client secret, token URL, and resource URL .

To use information collected by Intune to make access control decisions, you need to set up another authentication source as HTTP type, referencing the Intune extension . This type of authentication source allows CPPM to use REST API calls to communicate with Intune and retrieve the device compliance status . You also need to configure the OAuth 2.0 settings for the authentication source, such as the client ID, client secret, token URL, and resource URL .

 This is because an Endpoint Context Server (ECS) is a feature that allows ClearPass to receive contextual information from external sources, such as Aruba Central, and use it for policy enforcement and reporting. An ECS can be configured to point to the Aruba Central API and fetch data such as device type, category, OS, applications, traffic flows, etc.

An ECS can be used to communicate the information that an IoT client has used SSH to Aruba ClearPass Policy Manager (CPPM). The ECS can query the Aruba Central API and retrieve the network traffic flows of the wireless IoT devices that are categorized as “Raspberry Pi” clients. The ECS can then filter the traffic flows by the SSH protocol and send the relevant information to CPPM. CPPM can then use this information for policy decisions, such as allowing or denying SSH access, or triggering alerts or actions.

B. On CPPM enable Device Insight integration. This is not a valid step because Device Insight is a feature that allows ClearPass to discover, profile, and fingerprint devices on the network using deep packet inspection (DPI) and machine learning (ML). Device Insight does not communicate with Aruba Central or receive information from it. Moreover, Device Insight might not be able to detect SSH traffic on encrypted wireless IoT devices without decrypting it first.

C. On Central configure APs and gateways to use CPPM as the RADIUS accounting server. This is not a valid step because RADIUS accounting is a feature that allows network devices to send periodic updates about the status and activity of authenticated users or devices to a RADIUS server, such as CPPM. RADIUS accounting does not communicate with Aruba Central or receive information from it. Moreover, RADIUS accounting might not be able to capture SSH traffic on wireless IoT devices without inspecting it first.

D. On Central set up CPPM as a Webhook application. This is not a valid step because Webhook is a feature that allows Aruba Central to send notifications or events to external applications or services using HTTP requests. Webhook does not communicate with CPPM or send information to it. Moreover, Webhook might not be able to send SSH traffic information on wireless IoT devices without filtering it first.

The subnet mask in rule 3 of the “medical-mobile” policy is currently 255.255.252.0, which means that the rule denies access to the 10.1.12.0/22 subnet as well as the adjacent 10.1.16.0/22 subnet 1. This is not consistent with the scenario requirements, which state that only the 10.1.12.0/22 subnet should be denied access, while the rest of the 10.1.0.0/16 range should be permitted access.

To fix this issue, the subnet mask in rule 3 should be changed to 255.255.248.0, which means that the rule only denies access to the 10.1.8.0/21 subnet, which includes the 10.1.12.0/22 subnet 1. This way, the rule matches the scenario requirements more precisely.

 This is because this URI specifies the exact attribute that contains the number of access rejects from the RADIUS server, which is the information that the NAE script needs to monitor and trigger an alert.

A. /rest/v1/system/vrfs/mgmt/radius/servers/cp.acnsxtest.local/2083/tcp?attributes=authstatistics. This is not the correct URI because it returns the entire authstatistics object, which contains more information than the access rejects, such as access accepts, challenges, timeouts, etc. This might make the NAE script more complex and inefficient to parse and process the data.

B. /rest/v1/system/vrfs/mgmt/radius/servers/cp.acnsxtest.local/2083/tcp?attributes=authstatistics?attributes=access_rejects. This is not a valid URI because it has two question marks, which is a syntax error. The question mark is used to indicate the start of the query string, which can have one or more parameters separated by ampersands. The correct way to specify multiple attributes is to use a comma-separated list after the question mark, such as ?attributes=attr1,attr2,attr3.

C. /rest/v1/system/vrfs/mgmt/radius/_servers/cp.acnsxtest.local/2083/tcp. This is not a valid URI because it has an extra underscore before servers, which is a typo. The correct resource name is servers, not _servers. Moreover, this URI does not specify any attributes, which means it will return the default attributes of the RADIUS server object, such as name, port, protocol, etc., but not the authstatistics or access_rejects.

7of30

According to the AOS-CX User Guide, one way to configure the VLAN setting for the reception role is to assign a consistent name to VLAN 14, 24, or 34 on each access layer switch and reference that name in the enforcement profile VLAN settings. This way, the switches can download the role settings from CPPM and apply the correct VLAN based on the name, rather than the ID. For example, the enforcement profile VLAN settings could be:

And the VLAN configuration on each switch could be:

According to the AOS-CX Switches Multiple Vulnerabilities1, one of the vulnerabilities (CVE-2021-41000) affects the SSH service on AOS-CX switches. This vulnerability allows an unauthenticated remote attacker to cause a denial-of-service condition on the switch by sending specially crafted SSH packets. The impact of this vulnerability is high, as it could result in a loss of management access and network disruption. Therefore, one recommendation to make is to create a control plane ACL to limit the sources that can access the switch with SSH. This way, the switch can filter out unwanted or malicious SSH traffic and reduce the risk of exploitation.

A DNS SAN (Subject Alternative Name) is an extension of the X.509 certificate standard that allows specifying additional hostnames or IP addresses that the certificate can be used for. A DNS SAN is useful for validating the identity of the server or client that presents the certificate, especially when the common name (CN) field does not match the hostname or IP address of the server or client.

In this case, the certificate has a CN of mc41.site94.example.com, which is the fully qualified domain name (FQDN) of the standalone Aruba Mobility Controller (MC). However, this CN may not match the hostname or IP address that the MC uses for the Web UI or for implementing RadSec with Aruba ClearPass Policy Manager. For example, if the MC uses a different FQDN, such as mc41.example.com, or an IP address, such as 192.168.1.41, for these purposes, then the certificate would not be valid for them. Therefore, the certificate should have a DNS SAN that includes all the possible hostnames or IP addresses that the MC may use for the Web UI and RadSec.

The UBT solution requires that the VLAN assignments for the wired clients are done by the gateway, not by the switch. Therefore, the role configurations on the gateways should not have any VLAN assignments, as they would override the VLAN 20 that is specified in the enforcement profile. Instead, the role configurations should only have policies that define the access rights for the clients in the “eth-internet” role. This way, the gateway can assign the clients to VLAN 20 and apply the appropriate policies based on their role1

The correct answer is D. Enabling alerts and email notifications for events related to gateway IPS engine utilization and errors.

Gateway IDS/IPS is a feature that allows the Aruba gateways to monitor and block malicious or unwanted traffic based on predefined or custom rules 1. The Fail Strategy is a setting that determines how the gateways handle traffic when the IPS engine fails or crashes 2. The Block option means that the gateways will stop forwarding traffic until the IPS engine recovers, while the Bypass option means that the gateways will continue forwarding traffic without inspection 2.

The Block option provides more security, but it also increases the risk of network outages if the IPS engine fails frequently or for a long time 2. To minimize this risk, it is recommended to enable alerts and email notifications for events related to gateway IPS engine utilization and errors 3. This way, the network administrators can be informed of any issues with the IPS engine and take appropriate actions to restore or troubleshoot it 3.

The other options are not correct or relevant for this issue:

• Option A is not correct because configuring a relatively high threshold for the gateway threat count alerts would not help minimize unexpected outages caused by using the Block option. The gateway threat count alerts are used to notify the network administrators of the number of threats detected by the IPS engine, but they do not affect how the gateways handle traffic when the IPS engine fails 4.
• Option B is not correct because making sure that the gateways have formed a cluster and operate in default gateway mode would not help minimize unexpected outages caused by using the Block option. The gateway cluster mode is used to provide high availability and load balancing for the gateways, but it does not affect how the gateways handle traffic when the IPS engine fails . The default gateway mode is used to enable routing and NAT functions on the gateways, but it does not affect how the gateways handle traffic when the IPS engine fails .
• Option C is not correct because setting the IDS or IPS policy to the least restrictive option, Lenient, would not help minimize unexpected outages caused by using the Block option. The IDS or IPS policy is used to define what rules are applied by the IPS engine to inspect and block traffic, but it does not affect how the gateways handle traffic when the IPS engine fails 2. The Lenient option contains fewer and older rules than the Moderate or Strict options, which means that it provides less security and more false negatives .

This option allows CPPM to receive real-time information about the network activity and security posture of the clients from the firewall, and then apply appropriate enforcement actions based on the configured policies 12. For example, if a client is detected to be infected with malware or violating the network usage policy, CPPM can quarantine or disconnect the client from the network 2.

Dynamic authorization is a feature that allows CPPM to send change of authorization (CoA) or disconnect messages to the MC to modify or terminate a user session based on certain conditions or events 1. Dynamic authorization uses the RFC 3576 protocol, which is an extension of the RADIUS protocol 2.

To enable dynamic authorization on the MC, you need to configure the IP address and UDP port of the CPPM server as the RFC 3576 server on the MC 3. The default UDP port for RFC 3576 is 3799, but it can be changed on the CPPM server . The MC and CPPM must use the same UDP port for dynamic authorization to work properly 3.

In this scenario, the MC is configured with the IP address of the CPPM server (10.47.47.8) as the RFC 3576 server, but it is using the default UDP port of 3799. However, according to the exhibit, the CPPM server is using a different UDP port of 1700 for dynamic authorization . This mismatch causes the CoA requests from CPPM to fail on the MC, as shown by the statistics .

To fix this issue, you need to change the UDP port in the MCs’ RFC 3576 server config to match the UDP port used by CPPM, which is 1700 in this case. Alternatively, you can change the UDP port in CPPM to match the default UDP port of 3799 on the MC. Either way, you need to ensure that both devices use the same UDP port for dynamic authorization 3 .

The exhibit shows a screenshot of a Malwarebytes alert that indicates that a website was blocked due to compromise. The alert contains the following information:

• The type of protection: Web Protection
• The website that was blocked: 10.254.1.21
• The port that was used: 80
• The process that initiated the connection: C:\Program Files (x86)\Google\Chrome\Application\chrome.exe
• The IP address of the device that initiated the connection: 10.1.26.151

The IP address of the device that initiated the connection is the one that should be recorded as a possibly compromised client, as it indicates that the device tried to access a malicious website that could infect it with malware or steal its data. In this case, the IP address of the possibly compromised client is 10.1.26.151.