HPE6-A78 Exam Dumps : Aruba Certified Network Security Associate Exam

The scenario involves AOS-CX switches in a two-tier topology with Switch-1 as the core switch (default router) on VLAN 100 and Switch-2 as an access layer switch with VLANs 15 and 25, where end-user devices connect. The goal is to protect against exploits from untrusted end-user devices, such as DHCP spoofing or ARP poisoning attacks, which are common threats in access layer networks.

DHCP Snooping: This feature protects against rogue DHCP servers by filtering DHCP messages. It should be enabled on the access layer switch (Switch-2) where end-user devices connect, specifically on the VLANs where these devices reside (VLANs 15 and 25). DHCP snooping builds a binding table of legitimate IP-to-MAC mappings, which can be used by other features like ARP inspection.

ARP Inspection: This feature prevents ARP poisoning attacks by validating ARP packets against the DHCP snooping binding table. It should also be enabled on the access layer switch (Switch-2) on VLANs 15 and 25, where untrusted devices are connected.

Option B, "On Switch-2, enable DHCP snooping globally and on VLANs 15 and 25. Later, enable ARP inspection on the same VLANs," is correct. DHCP snooping must be enabled first to build the binding table, and then ARP inspection can use this table to validate ARP packets. This configuration should be applied on Switch-2, the access layer switch, because that’s where untrusted end-user devices connect.

Option A, "On Switch-1, enable ARP inspection on VLAN 100 and DHCP snooping on VLANs 15 and 25," is incorrect. Switch-1 is the core switch and does not directly connect to end-user devices on VLANs 15 and 25. DHCP snooping and ARP inspection should be enabled on the access layer switch (Switch-2) where the devices reside. Additionally, enabling ARP inspection on VLAN 100 (where the DHCP server is) is unnecessary since the DHCP server is a trusted device.

Option C, "On Switch-2, enable BPDU filtering on all edge ports in order to prevent eavesdropping attacks by untrusted devices," is incorrect. BPDU filtering is used to prevent spanning tree protocol (STP) attacks by blocking BPDUs on edge ports, but it does not protect against eavesdropping or other exploits like DHCP spoofing or ARP poisoning, which are more relevant in this context.

Option D, "On Switch-1, enable DHCP snooping on VLAN 100 and ARP inspection on VLANs 15 and 25," is incorrect for the same reason as Option A. Switch-1 is not the appropriate place to enable these features since it’s not directly connected to the untrusted devices on VLANs 15 and 25.

The HPE Aruba Networking AOS-CX 10.12 Security Guide states:

"DHCP snooping should be enabled on access layer switches where untrusted end-user devices connect. It must be enabled globally and on the specific VLANs where the devices reside (e.g., dhcp-snooping vlan 15,25). This feature builds a binding table of IP-to-MAC mappings, which can be used by Dynamic ARP Inspection (DAI) to prevent ARP poisoning attacks. DAI should also be enabled on the same VLANs (e.g., ip arp inspection vlan 15,25) after DHCP snooping is configured, ensuring that ARP packets are validated against the DHCP snooping binding table." (Page 145, DHCP Snooping and ARP Inspection Section)

Additionally, the guide notes:

"Dynamic ARP Inspection (DAI) and DHCP snooping are typically configured on access layer switches to protect against exploits from untrusted devices, such as DHCP spoofing and ARP poisoning. These features should be applied to the VLANs where end-user devices connect, not on core switches unless those VLANs are directly connected to untrusted devices." (Page 146, Best Practices Section)

In ArubaOS firewall policies, using network aliases allows administrators to manage groups of IP addresses more efficiently. By associating multiple IPs with a single alias, any changes made to the alias (like adding or removing IP addresses) are automatically reflected in all firewall rules that reference that alias. This significantly simplifies the management of complex rulesets and ensures consistency across security policies, reducing administrative overhead and minimizing the risk of errors.

In ArubaOS-CX, managing and searching logs can be crucial for tracking and diagnosing issues related to network operations such as port authentication. To efficiently find logs related to port authentication, configuring a logging filter specifically for this category is highly effective.

Logging Filter Configuration: In ArubaOS-CX, you can configure logging filters to refine the logs that are collected and viewed. By setting up a filter for the "port-access" category, you focus the logging system to only capture and display entries related to port authentication events. This approach reduces the volume of log data to sift through, making it easier to identify relevant issues.

Global Application of Filter: Applying the filter globally ensures that all relevant log messages, regardless of their origin within the switch's modules or interfaces, are captured under the specified category. This global application is crucial for comprehensive monitoring across the entire device.

Alternative Options and Their Evaluation:

Option A: Adding "-C and *-c port-access" to the "show logging" command is not a standard command format in ArubaOS-CX for filtering logs directly through the show command.

Option C: Enabling debugging for "portaccess" indeed increases the detail of logs but primarily serves to provide real-time diagnostic information rather than filtering existing logs.

Option D: Specifying a logging facility focuses on routing logs to different destinations or subsystems and does not inherently filter by log category like port-access.