FCSS_EFW_AD-7.4 FCSS - Enterprise Firewall 7.4 Administrator Questions and Answers

From the exhibit, ISFW is part of a Security Fabric environment with NGFW-1 as the Fabric Root. In this architecture, FortiGate devices share security intelligence, including logs and detected threats.

ISFW is in a Security Fabric environment:

● Security Fabric allows devices like ISFW toreceive threat intelligencefrom NGFW-1, even if UTM is not enabled locally.

● If NGFW-1 detects malware fromIP 10.1.10.1 to 89.238.73.97, this information can bepropagated to ISFW and FortiAnalyzer.

The firewall policy in NGFW-1 has UTM enabled:

● Even thoughISFW does not have UTM enabled, NGFW-1 (which sits between ISFW and the external network)does have UTM enabledand is scanning traffic.

● Since NGFW-1 detects malware in the session, it logs the event, which is then sent toFortiAnalyzer.

False positives inIntrusion Prevention System (IPS)analysis can disrupt legitimate traffic and negatively impact user experience. To reduce false positives while maintaining security, administrators can:

●Use IPS profile extensions to fine-tune the settings based on the organization's environment.

●Select the correct operating system, protocol, and application typesto ensure that IPS signatures match the network's actual traffic patterns, reducing false positives.

●Customize signature selectionbased on the network’s specific services, filtering out unnecessary or irrelevant signatures.

When configuring aloopback interface as the BGP sourceforconnecting to an ISP, two important settings must be applied:

1.Enable EBGP Multihop (ebgp-enforce-multihop)

BGP normally expects directly connected neighbors, but since the ISP and FortiGate A are usingloopback interfaces,packets will not be sent directly between their physical interfaces.

Theebgp-enforce-multihopcommandallows BGP to form an eBGP peering over multiple hops.

2.Set the Update Source (update-source)

Since FortiGate is using aloopback interface as the source, theupdate-sourcecommand ensures thatBGP updates originate from the loopback interfacerather than a physical interface.

This is essential becauseBGP peers must match the source IP with the configured neighbor address.

When configuringADVPN (Auto-Discovery VPN)to connectoverlay networks across different hubs using IBGP and EBGP, special configurations are required to allow spokes from different overlay networks to dynamically establish tunnels.

●set auto-discovery-crossover enable

● Thisallows cross-hub tunnel discoveryin an ADVPN deployment where multiple hubs are used.

● SinceHub A and Hub Bbelong to different overlays, enablingcrossover discoveryensures that spokes from one overlay can dynamically create direct tunnels to spokes in the other overlay when needed.

●set enforce-multihop enable

● This setting ensures thatBGP peers using loopback interfacescan establish connectivityeven if they are not directly connected.

●Multihop BGP sessionsare required when usingloopback addresses as BGP peer sourcesbecause the connection might need to traverse multiple routers before reaching the BGP neighbor.

● This is especially useful inADVPN deployments with multiple hubs, where routes might need to cross from one hub to another.

Theset tcp-mss-senderandset tcp-mss-receivercommands in afirewall policyallow an administrator to adjust theMaximum Segment Size (MSS)of TCP packets.

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

●set tcp-mss-senderadjusts the MSS value foroutgoing TCP traffic.

●set tcp-mss-receiveradjusts the MSS value forincoming TCP traffic.

This helps prevent issues withfragmentationandMTU mismatches, improving network performance and avoiding retransmissions.

ThisIPsec Phase 1 configurationdefines adynamicVPN tunnel that can accept connections from multiple peers. The settings chosen here suggest a configuration optimized fornetworks with intermittent traffic patternswhile ensuring resources are used efficiently.

Key configurations and their impact:

●set type dynamic→ This allows multiple peers to establish connections dynamically without needing predefined IP addresses.

●set ike-version 2→ UsesIKEv2, which is more efficient and supports features like EAP authentication and reduced rekeying overhead.

●set dpd on-idle→ Dead Peer Detection (DPD) is triggeredonly when the tunnel is idle, reducing unnecessary keep-alive packets and improving resource utilization.

●set add-route enable→ FortiGate automatically adds the route to the routing table when the tunnel is established, ensuring connectivity when needed.

●set proposal aes128-sha256 aes256-sha256→ Uses strong encryption and hashing algorithms, ensuring a secure connection.

●set keylife 28800→ Sets alonger key lifetime(8 hours), reducing the frequency of rekeying, which is beneficial for stable connections.

BecauseDPD is set to on-idle, the tunnel will not constantly send keep-alive messages but will still ensure connectivity when traffic is detected. This makes the configuration ideal fornetworks with regular but non-continuous traffic, balancing security and resource efficiency.

Zero phase selectors inIPsec Phase 2mean thatno specific traffic selectors (subnets) are defined, allowingany traffic to be encryptedthrough the VPN tunnel. This can causeunintended traffic forwarding issuesand disrupt network operations.

To prevent this from happening during future migrations:

●Using routing protocolsensures thatonly specific subnets are advertised over the tunnel. Dynamic routing (such as OSPF or BGP) helps define which networks should use the tunnel, preventing unintended traffic from being encrypted.

●Clearly defining phase 2 selectorsavoids the problem of encrypting all traffic byexplicitly stating the allowed source and destination subnets. This prevents the tunnel from affecting unrelated network traffic.

In thisADVPN (Auto-Discovery VPN) network, there are two hubs (Hub A and Hub B) connected viaEBGP, whileIBGPis used within each overlay. To ensure proper BGP routing between the overlays, the administrator must configure specific BGP options..

set ebgp-enforce-multihop enable

By default, EBGP requires directly connected neighbors. Since Hub A and Hub B are not directly connected but reach each other over an IPsec tunnel, multihop must be enabled for EBGP sessions to work.

set next-hop-self enable

In IBGP, the next-hop attribute does not change by default. When an IBGP route is advertised from a spoke to another hub or spoke, the next-hop needs to be updated to ensure proper reachability. Enabling next-hop-self forces the BGP speaker to advertise itself as the next-hop, ensuring that all spokes properly reach routes across the overlays.

In atransparent mode Virtual Domain (VDOM)configuration, FortiGate operates as aLayer 2 bridgerather than performing Layer 3 routing. Theset forward-domain <domain_ID>command is used to control how traffic is forwarded between interfaces within the sametransparent VDOM.

Aforward-domainacts as abroadcast domain, meaning only interfaces with thesame forward-domain IDcan exchange traffic. This setting is commonly used toseparate different VLANs or network segmentswithin the transparent VDOM while still allowing FortiGate to apply security policies.

IKEv2 (Internet Key Exchange version 2) is an improvement over IKEv1, offering enhanced security, efficiency, and flexibility in VPN configurations.

It includes stronger Diffie-Hellman (DH) groups, such as Elliptic Curve (ECP) groups.

IKEv2 supports stronger cryptographic algorithms, includingElliptic Curve Diffie-Hellman (ECDH)groups such asECP256 and ECP384, providing improved security compared to IKEv1.

It supports the extensible authentication protocol (EAP).

IKEv2 natively supports EAP authentication, which allows integration with external authentication mechanisms such asRADIUS, certificates, and smart cards. This is particularly useful forremote access VPNswhere user authentication must be flexible and secure.

Thebest wayto block outdated SSL/TLS versions is toconfigure the SSL/SSH inspection profileto enforce aminimum SSL/TLS versionand disable weak SSL versions.

By setting theminimum allowed SSL versionin theHTTPS settings of the SSL/SSH inspection profile, FortiGate will:

● Block any connection usingoutdated SSL/TLS versions(such as SSLv3, TLS 1.0, or TLS 1.1).

● Enforce secure communication usingonly strong SSL/TLS versions(such as TLS 1.2 or TLS 1.3).

● Protect users fromman-in-the-middle (MITM) and downgrade attacksthat exploit weak encryption.

TheFortinet FGSP (FortiGate Session Life Support Protocol) clusterallows session synchronization betweentwo FortiGate devicesto provide seamless failover. However,ICMP (ping) is a connectionless protocol, and by default, FortiGate does not synchronize connectionless sessions unless explicitly enabled.

In the exhibit:

● The commandget system session list | grep icmponFortiGate_Breturnsno output, meaning that ICMP sessions arenot being synchronizedfrom FortiGate_A.

● Ifsession-pickup-connectionlessis disabled,FortiGate_B will not receive ICMP sessions, causingpacket lossduring failover.

InADVPN (Auto-Discovery VPN) configurations, security concerns includeprotecting peer IDsduring VPN establishment. Peer IDs are exchanged in theIKE (Internet Key Exchange) negotiation phase, and their exposure could lead toprivacy risks or targeted attacks.

●IKEv2 encrypts peer IDs, making itmore securecompared to IKEv1, where peer IDs can beexposed in plaintextin aggressive mode.

●IKEv2 also provides better performance and flexibilitywhile supporting dynamic tunnel establishment in ADVPN.

FortiGate, like other security appliances, cannot analyze encrypted HTTPS traffic unless itdecryptsit first. Ifonly certificate inspectionis enabled, FortiGate can see the certificate details (such as the domain and issuer) butcannot inspect the actual web content.

To fully analyze the traffic and detect potential malware threats:

●Full SSL inspection (Deep Packet Inspection)must be enabled in theSSL/SSH Inspection Profile.

● This allows FortiGate todecrypt the HTTPS traffic, inspect the content, and then re-encrypt it before forwarding it to the user.

● Without full SSL inspection, threats embedded in encrypted traffic may go undetected.