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

• 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

The infected host cloud feed is a list of IP addresses that have been identified as compromised or infected by malware. The feed is updated by Juniper ATP Cloud based on the detection of malicious activity from the hosts, such as contacting known command-and-control servers. When a host on the network reaches the configured threat level threshold, its IP address is automatically added to the infected host cloud feed and blocked from communicating with any other hosts on the Internet. The other feeds are not relevant for this situation. The command-and-control cloud feed is a list of IP addresses that are known to be used by malware for remote control and communication. The allowlist and blocklist feed is a user-defined list of IP addresses that are either allowed or denied by the SRX Series device. The custom cloud feed is a user-defined list of IP addresses that are associated with a specific category or threat level. References:

• Infected Hosts: More Information
• Juniper’s Attacker IP feed bolsters threat protection with SecIntel
• ATP Appliance and SRX Series Threat Level Comparison Chart