Paloalto Networks Updated PCNSE Exam Questions and Answers by conor

The Test Policy Match tool in PAN-OS allows administrators to simulate traffic against the current security policy set to verify how it will be handled. By inputting source/destination IPs, ports, protocols, and other parameters, it shows which rule matches and whether the traffic is allowed or denied, making it ideal for ensuring unwanted traffic is blocked.

The table displays NAT rules configured on the firewall. The key points are:

Source Zone and Destination Zone define the traffic flow.

Source Address and Destination Address specify the IP addresses involved.

Service indicates the type of traffic (e.g., any, ping).

Source Translation and Destination Translation show the translated IP addresses for NAT.

Issue and Resolution Options

The application server at 192.168.197.40 can establish outbound connections but faces issues with inbound connections due to the shared NAT IP 198.51.100.88. The external database server cannot establish a secure connection back to 192.168.197.40.

Options to Resolve the Issue:

Replace the Two NAT Rules with a Single Rule:

Combining both DMZ servers into one NAT rule might simplify configuration but could cause issues in distinguishing inbound traffic for each server.

Pros: Simplifies rule management.

Cons: Might not address the inbound traffic issue properly.

New Public IP Address:

Obtaining a new public IP address for the new server (192.168.197.40) ensures dedicated inbound and outbound NAT.

Pros: Clear separation of traffic, resolves inbound connectivity issues.

Cons: Requires additional public IP.

Separate Source NAT and Destination NAT Rules:

Configuring distinct NAT rules for source and destination addresses without using the bidirectional option.

Pros: Clear and distinct rules for each direction of traffic.

Cons: More complex to manage, might require more firewall resources.

Move the NAT Rule:

Adjusting the order of NAT rules to prioritize the new server’s rule.

Pros: Simple reordering might resolve prioritization conflicts.

Cons: Might not fully resolve the inbound connection issue.

To address the issue of application performance degradation due to excessive VoIP traffic, the administrator should configure QoS on the egress interface for the traffic flows and a QoS profile defining traffic classes. QoS stands for Quality of Service, which is a feature that allows the firewall to manage bandwidth usage and prioritize traffic based on various criteria, such as application, user, service, etc. QoS can help improve the performance and quality of latency-sensitive applications, such as VoIP, by guaranteeing them sufficient bandwidth and priority over other traffic1.

To enable QoS on the firewall, the administrator needs to create a QoS profile and a QoS policy. A QoS profile defines the eight classes of service that traffic can receive, including priority, guaranteed bandwidth, maximum bandwidth, and weight. A QoS policy identifies the traffic that matches a specific class of service based on source and destination zones, addresses, users, applications, services, etc2. The administrator can also create a custom QoS profile or use the default one.

The administrator should apply QoS on the egress interface for the traffic flows, which is the interface where the traffic leaves the firewall. This is because QoS can only shape outbound traffic and not inbound traffic. The egress interface can be either internal or external, depending on the direction of the VoIP traffic. For example, if the VoIP traffic is from internal users to external servers, then the egress interface is the untrust interface facing the ISP. If the VoIP traffic is from external users to internal servers, then the egress interface is the trust interface facing the LAN3.

The administrator should assign a high priority and a sufficient guaranteed bandwidth to the VoIP traffic in the QoS profile. This will ensure that the VoIP packets are processed first by the firewall and are not dropped or delayed due to congestion. The administrator can also limit or block other applications that consume too much bandwidth or pose security risks in the same or different QoS classes4.

An Application Override policy for SIP traffic is not necessary to address this issue. An Application Override policy is used to change or customize the App-ID of certain traffic based on port and protocol criteria. This can be useful for optimizing performance or security for some applications that are difficult to identify or have non-standard behaviors. However, SIP is a predefined App-ID that identifies Session Initiation Protocol (SIP) traffic, which is commonly used for VoIP signaling. The firewall can recognize SIP traffic without an Application Override policy5.

QoS on the ingress interface for the traffic flows is not effective to address this issue. As mentioned earlier, QoS can only shape outbound traffic and not inbound traffic. Applying QoS on the ingress interface will not have any impact on how the firewall handles or prioritizes the incoming packets6.

A QoS policy for each application is not required to address this issue. A QoS policy can match multiple applications in a single rule by using application filters or application groups. This can simplify and consolidate the QoS policy configuration and management. The administrator does not need to create a separate QoS policy for each application unless there is a specific need to assign different classes of service or parameters to each application7.

References: QoS Overview, Configure QoS, QoS Use Cases, QoS Best Practices, Application Override, QoS FAQ, Create a QoS Policy Rule