Paloalto Networks Updated PCNSE Exam Questions and Answers by jai

When sizing a decryption firewall deployment, two factors that should be considered are the encryption algorithm and the TLS protocol version. These factors affect the amount of resources and processing power that the firewall needs to decrypt and inspect SSL/TLS traffic.

The encryption algorithm is the method that the server and the client use to encrypt and decrypt the data exchanged in an SSL/TLS session. Different encryption algorithms have different levels of security and performance. For example, AES is a symmetric encryption algorithm that is faster and more efficient than RSA, which is an asymmetric encryption algorithm. However, RSA is more secure than AES because it uses public and private keys to encrypt and decrypt data, while AES uses a single shared key. The firewall must support the encryption algorithms that are used by the servers and clients that it decrypts, and it must have enough CPU and memory resources to handle the decryption workload12.

The TLS protocol version is the standard that defines how the server and the client establish and maintain an SSL/TLS session. Different TLS protocol versions have different features and requirements for encryption algorithms, cipher suites, certificates, handshake messages, etc. For example, TLS 1.3 is the latest and most secure version of TLS, which supports only strong encryption algorithms and cipher suites, such as AES-GCM and ChaCha20-Poly1305, and requires elliptic curve certificates. The firewall must support the TLS protocol versions that are used by the servers and clients that it decrypts, and it must have enough hardware acceleration resources to handle the decryption speed34.

The number of security zones in decryption policies and the number of blocked sessions are not relevant factors for sizing a decryption firewall deployment. The number of security zones in decryption policies only affects how the firewall matches traffic to decryption rules based on source and destination zones, but it does not affect the decryption performance or resource consumption. The number of blocked sessions only indicates how many sessions are denied by the firewall based on security policy or decryption policy rules, but it does not affect the decryption capacity or throughput56.

References: Encryption Algorithms, TLS Protocol Versions, Decryption Policy, PCNSE Study Guide (page 60)

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In Palo Alto Networks firewalls, the order of evaluation for blocking access to specific URLs involves several components, including URL Filtering profiles and Security policy rules. Among the options listed, the Custom URL category in a Security policy rule is evaluated last in the processing order. This is because the firewall processes Security policy rules after URL Filtering profiles. If a URL matches a Custom URL category in a Security policy rule, this rule will override any allow actions in URL Filtering profiles due to the hierarchical nature of policy evaluation. Security policies provide the final verdict on whether traffic is allowed or denied, making them the last line of evaluation for access control, including URL blocking.

An authentication portal is a feature that can be used to identify guests and BYOD users, instruct them how to download and install the CA certificate, and clearly notify them that their traffic will be decrypted. An authentication portal is a web page that the firewall displays to users who need to authenticate before accessing the network or the internet. The authentication portal can be customized to include a welcome message, a login prompt, a disclaimer, a certificate download link, and a logout button. The authentication portal can also be configured to use different authentication methods, such as local database, RADIUS, LDAP, Kerberos, or SAML1. By using an authentication portal, the firewall can redirect BYOD users to a web page where they can learn about the decryption policy, download and install the CA certificate, and agree to the terms of use before accessing the network or the internet2.

An SSL decryption profile is not a feature that can be used to identify guests and BYOD users, instruct them how to download and install the CA certificate, and clearly notify them that their traffic will be decrypted. An SSL decryption profile is a set of options that define how the firewall handles SSL/TLS traffic that it decrypts. An SSL decryption profile can include settings such as certificate verification, unsupported protocol handling, session caching, session resumption, algorithm selection, etc3. An SSL decryption profile does not provide any user identification or notification functions.

An SSL decryption policy is not a feature that can be used to identify guests and BYOD users, instruct them how to download and install the CA certificate, and clearly notify them that their traffic will be decrypted. An SSL decryption policy is a set of rules that determine which traffic the firewall decrypts based on various criteria, such as source and destination zones, addresses, users, applications, services, etc. An SSL decryption policy can also specify which type of decryption to apply to the traffic, such as SSL Forward Proxy, SSL Inbound Inspection, or SSH Proxy4. An SSL decryption policy does not provide any user identification or notification functions.

Comfort pages are not a feature that can be used to identify guests and BYOD users, instruct them how to download and install the CA certificate, and clearly notify them that their traffic will be decrypted. Comfort pages are web pages that the firewall displays to users when it blocks or fails to decrypt certain traffic due to security policy or technical reasons. Comfort pages can include information such as the reason for blocking or failing to decrypt the traffic, the URL of the original site, the firewall serial number, etc5. Comfort pages do not provide any user identification or notification functions before decrypting the traffic.

References: Configure an Authentication Portal, Redirect Users Through an Authentication Portal, SSL Decryption Profile, Decryption Policy, Comfort Pages

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