When handling traffic that is destined for itself, the SRX examines the host-inbound-traffic configuration for the ingress interface and the associated security zone. It evaluates whether the traffic should be allowed based on this configuration. Traffic not addressed to the ingress interface is handled based on security policies within the junos-host zone, which applies to traffic directed to the SRX itself. For more details, refer to Juniper Host Inbound Traffic Documentation.
When handling traffic that is destined for the SRX device itself (also known as host-bound traffic), the SRX follows a specific process to evaluate the traffic and apply the appropriate security policies. The junos-host zone is a special security zone used for managing traffic destined for the device itself, such as management traffic (SSH, SNMP, etc.).
Explanation of Answer B (Packet to a Different Interface):
If the packet is destined for an interface other than the ingress interface, the SRX performs a security policy evaluation specifically for the junos-host zone. This ensures that management or host-bound traffic is evaluated according to the security policies defined for that zone.
Explanation of Answer C (Packet to the Ingress Interface):
If the packet is addressed to the ingress interface, the device first checks the host-inbound-traffic configuration for the ingress interface and zone. This configuration determines whether certain types of traffic (such as SSH, HTTP, etc.) are allowed to reach the device on that specific interface.
Step-by-Step Handling of Host-Bound Traffic:
bash
set security zones security-zone host-inbound-traffic system-services ssh
Security Policy for junos-host: Ensure policies are defined for managing traffic destined for the SRX device:
bash
set security policies from-zone to-zone junos-host policy allow-ssh match source-address any
set security policies from-zone to-zone junos-host policy allow-ssh match destination-address any
Juniper Security Reference:
Junos-Host Zone: This special zone handles traffic destined for the SRX device, including management traffic. Security policies must be configured to allow this traffic. Reference: Juniper Networks Host-Inbound Traffic Documentation.
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