FCSS_EFW_AD-7.6 FCSS - Enterprise Firewall 7.6 Administrator Questions and Answers

When standardizing the deployment of FortiGate devices across branches using FortiManager, the best practice is to use metadata variables. This allows for dynamic interface configuration while maintaining a single, consistent policy package for all branches.

● Metadata variables in FortiManager enable interface roles and configurations to be dynamically assigned based on the specific FortiGate device.

● This ensures scalability and consistent security policy enforcement across all branches without manually adjusting interface settings for each device.

● When a new branch FortiGate is deployed, metadata variables automatically map to the correct physical interfaces, reducing manual configuration errors.

VXLAN (Virtual Extensible LAN) is an overlay network technology that extends Layer 2 networks over Layer 3 infrastructure. When VXLAN is used extensively on FortiGate, hardware acceleration is crucial for maintaining performance.

● NP7 (Network Processor 7) is Fortinet’s latest network processor designed to accelerate high-performance networking features, including:

● VXLAN encapsulation/decapsulation

● IPsec VPN offloading

● Firewall policy enforcement

● Advanced threat protection at wire speed

NP7 significantly reduces latency and improves throughput when handling VXLAN traffic, making it the best choice for large-scale VXLAN deployments.

The OSPF database optimization is necessary to reduce unnecessary routing information and improve network performance. In the given topology, Area 0.0.0.1 is a non-backbone area connected to Area 0.0.0.0 (the backbone area) through an Area Border Router (ABR).

To optimize OSPF in this scenario, configuring Area 0.0.0.1 as a Stub Area will:

● Reduce the size of the OSPF database by preventing external routes (from outside OSPF) from being injected into Area 0.0.0.1.

● Allow only intra-area and inter-area routes, meaning routers in Area 0.0.0.1 will rely on a default route for external destinations.

● Improve convergence time and reduce router processing load since fewer LSAs (Link-State Advertisements) are exchanged.

The best way to automate a firewall policy using a daily updated list of IP addresses is by using an external connector from Threat Feeds. This allows FortiGate to dynamically retrieve real-time threat intelligence from external sources and apply it directly to security policies.

By configuring Threat Feeds, the administrator can:

● Automatically update firewall policies with the latest malicious IPs daily.

● Block traffic from those IPs in real-time without manual intervention.

● Integrate with FortiGuard, third-party threat intelligence sources, or custom feeds (CSV, STIX/TAXII, etc.).

When using IPsec VPNs and VXLAN, additional headers are added to packets, which can exceed the default 1500-byte MTU. This can lead to fragmentation issues, dropped packets, or degraded performance.

To resolve this, the MTU (Maximum Transmission Unit) should be adjusted only if all devices in the network path support it. Otherwise, some devices may still drop or fragment packets, leading to continued issues.

Why adjusting MTU helps:

● VXLAN adds a 50-byte overhead to packets.

● IPsec adds additional encapsulation (ESP, GRE, etc.), increasing the packet size.

● If packets exceed the MTU, they may be fragmented or dropped, causing intermittent connectivity issues.

● Lowering the MTU on interfaces ensures packets stay within the supported size limit across all network devices.

Applying an aggressive IPS profile without prior testing can disrupt legitimate applications by incorrectly identifying normal traffic as malicious. To prevent disruptions while still monitoring for threats:

● Enable IPS in "Monitor Mode" first:

● This allows FortiGate to log and analyze potential threats without actively blocking traffic.

● Administrators can review logs and fine-tune IPS signatures to minimize false positives before switching to blocking mode.

● Verify and adjust signature patterns:

● Some signatures might trigger unnecessary blocks for legitimate application traffic.

● By analyzing logs, administrators can disable or modify specific rules causing false positives.

The issue occurs because FortiGate enforces the "do not fragment" (DF) bit in the packet, and the packet size exceeds the MTU of the network path. When the Windows PC1 (with an MTU of 1500 bytes) attempts to send a 1400-byte packet, the FortiGate interface (with an MTU of 1000 bytes) needs to fragment it. However, since the DF bit is set, FortiGate drops the packet instead of fragmenting it.

To resolve this, the user should adjust the ping packet size to fit within the path MTU. In this case, reducing the packet size to 972 bytes (1000 bytes MTU minus 28 bytes for the IP and ICMP headers) should allow successful transmission.

Since Core1 and Core2 are not designated as management VDOMs, they rely on the root VDOM for connectivity to external resources such as FortiGuard updates. If the root VDOM lacks a VDOM link to these VDOMs or cannot reach FortiGuard services, security features like web filtering will stop working.

From the Root FortiGate - System Administrator Configuration exhibit:

● The AdminSSO account has the super_admin_readonly role.

From the Downstream FortiGate - Security Fabric Settings exhibit:

● The Security Fabric role is set to Join Existing Fabric, meaning it will authenticate with the root FortiGate.

● SAML Single Sign-On (SSO) is enabled, and the default admin profile is set to super_admin_readonly.

When the AdminSSO user logs into the downstream FortiGate using SSO, the authentication request is sent to the root FortiGate, where AdminSSO has super_admin_readonly permissions. Since the downstream FortiGate inherits this permission through the Security Fabric configuration, the user will be granted super_admin_readonly access.

The diagram shows a multi-area OSPF network where:

● FortiGate A is in OSPF Area 0 (Backbone area).

● FortiGate B is in OSPF Area 0.0.0.1 and is connected to an RIP network.

To ensure that OSPF Area 0 (0.0.0.0) learns routes from the external RIP network, FortiGate B must redistribute RIP routes into OSPF.

Steps to achieve this:

1. Enable route redistribution on FortiGate B to inject RIP-learned routes into OSPF.

2. This allows OSPF Area 0.0.0.1 to forward RIP routes to OSPF Area 0 (0.0.0.0), making the external network visible.

In a transparent mode Virtual Domain (VDOM) configuration, FortiGate operates as a Layer 2 bridge rather than performing Layer 3 routing. The set forward-domain <domain_ID> command is used to control how traffic is forwarded between interfaces within the same transparent VDOM.

A forward-domain acts as a broadcast domain, meaning only interfaces with the same forward-domain ID can exchange traffic. This setting is commonly used to separate different VLANs or network segments within the transparent VDOM while still allowing FortiGate to apply security policies.

When FortiGate processes the first packets of a session, it follows a sequence of steps to determine how the traffic should be handled before establishing a session. The initial step involves:

● Access Control List (ACL) checks: Determines if the traffic should be allowed or blocked based on predefined security rules.

● Hardware Packet Engine (HPE) inspections: Ensures that packet headers are valid and comply with protocol standards.

● IP Integrity Header Checking: Verifies if the IP headers are intact and not malformed or spoofed.

Once these security inspections are completed and the session is validated, FortiGate then installs the session in hardware (if offloading is enabled) or processes it in software.

The packet capture output displays a TLS Client Hello message from FortiGate to FortiManager Cloud. This message contains Server Name Indication (SNI), which is used to indicate the domain name that FortiGate is trying to connect to.

FortiGate will receive a certificate that supports multiple domains because FortiManager operates in a cloud computing environment.

● FortiManager Cloud hosts multiple customers and domains under a shared infrastructure.

● The TLS handshake includes SNI (Server Name Indication), which allows FortiManager Cloud to serve multiple certificates based on the requested domain.

● This means FortiGate will likely receive a multi-domain or wildcard certificate that can be used for multiple customers under FortiManager Cloud.

The wildcard for the domain .fortinet-ca2.support.fortinet.com must be supported by FortiManager Cloud.

● The SNI extension contains the domain 9398.support.fortinet-ca2.fortinet.com.

● FortiManager Cloud must support wildcard certificates such as *.fortinet-ca2.support.fortinet.com to securely manage multiple subdomains and customers.

● This ensures that FortiGate can validate the server certificate without any TLS errors.

The set tcp-mss-sender and set tcp-mss-receiver commands in a firewall policy allow an administrator to adjust the Maximum Segment Size (MSS) of TCP packets.

This setting controls the largest payload size that a device can handle in a single TCP segment, ensuring that packets do not exceed the allowed MTU (Maximum Transmission Unit) along the network path.

● set tcp-mss-sender adjusts the MSS value for outgoing TCP traffic.

● set tcp-mss-receiver adjusts the MSS value for incoming TCP traffic.

This helps prevent issues with fragmentation and MTU mismatches, improving network performance and avoiding retransmissions.