JN0-335 Exam Dumps : Security, Specialist (JNCIS-SEC)

 This is because the error message indicates that the client device does not trust the certificate authority that issued the certificate for the external server. Therefore, you need to import the root CA certificate from the SRX Series device to the client device and add it to the trusted certificate store. This will allow the client device to verify the identity of the SRX Series device and accept the certificates it generates for the external servers3.

The other options are not correct because:

• A. Load a known good, but expired. CA certificate onto the SRX Series device. This will not solve the problem because the client device will still reject the certificates from the SRX Series device if they are signed by an expired CA certificate. The expiration date of the CA certificate is one of the factors that the client device checks when validating the certificate2.
• B. Install a new SRX Series device to act as the client proxy. This will not solve the problem because the new SRX Series device will still need to have a root CA certificate configured and imported to the client devices. The problem is not with the SRX Series device itself, but with the trust relationship between the SRX Series device and the client devices2.
• C. Reboot the SRX Series device. This will not solve the problem because rebooting the SRX Series device will not change the configuration or the certificates on the SRX Series device or the client devices. The problem is not caused by a temporary glitch or a malfunction, but by a mismatch between the certificates on the SRX Series device and the client devices2.

I hope this helps you understand the problem and the solution better. If you want to learn more about SSL client protection proxy, you can check out the following references:

• SSL Proxy Overview
• Configuring SSL Forward Proxy
• Configuring a Root CA Certificate
• SSL Proxy - Client Protection

• A stateful firewall in SRX Series devices keeps track of the state of network connections, distinguishing legitimate packets for different types of connections and allowing only packets that match a known active connection. Sessions are created when a TCP SYN packet is received and permitted by the security policy1.
• A security policy is a set of rules that defines how traffic is processed by the SRX Series device. A security policy applies the security rules to the transit traffic within a context (from-zone to to-zone) and each policy is uniquely identified by its name. The traffic is classified by matching the source and destination zones, the source and destination addresses, and the application that the traffic carries in its protocol headers with the policy database in the data plane2.
• A Layer 3 route is a path that a packet takes to reach its destination based on the destination IP address. The SRX Series device performs a longest-match Layer 3 route table lookup to determine the next hop for the packet3.
• An Application Layer Gateway (ALG) is a software component that provides application-level awareness, security, and control for specific protocols. An ALG inspects the application-layer payload of a packet and modifies it if necessary to allow the application to traverse the SRX Series device. For example, an ALG can rewrite IP addresses and port numbers in the payload of FTP or SIP packets4.
• The sequence that an SRX Series device uses when implementing stateful session security policies using Layer 3 routes is as follows3:

References:

• 1: Traffic Processing on SRX Series Firewalls Overview | Junos OS | Juniper Networks
• 2: Best Practices for Defining Policies on High-End SRX Series Devices - TechLibrary - Juniper Networks
• 3: [SRX] Example: Configuring TCP SYN Check options on a per-policy basis
• 4: Application Layer Gateways Overview | Junos OS | Juniper Networks