FCSS_EFW_AD-7.4 Questions and Answers

FortiGate'sIPS protocol decodersanalyzenetwork transmission patternsandapplication signaturesto identify and block malicious traffic.Application Controlis the feature that allows FortiGate todetect, classify, and block applicationsbased on their behavior and signatures, even when they do not rely on traditional URLs.

●Application Controlworks alongsideIPS protocol decodersto inspect packet payloads and enforce security policies based on recognized application behaviors.

● It enablesgranular control over non-URL-based applicationssuch asP2P traffic, VoIP, messaging apps, and other non-web-based protocolsthat IPS can identify through protocol decoders.

●IPS and Application Control together can detect evasive or encrypted applications that might bypass traditional firewall rules.

TheInternet Service Database (ISDB)in FortiGate is used to enforce content filtering atLayer 3 (Network Layer) and Layer 4 (Transport Layer)of the OSI model by identifying applications based on theirpredefined IP addresses and ports.

FortiGate has a predefined list of all IPs and ports for specific applications downloaded from FortiGuard:

● FortiGate retrieves and updates apredefined listof IPs and ports for different internet services fromFortiGuard.

● This allows FortiGate to block specific services atLayer 3 and Layer 4without requiring deep packet inspection.

The ISDB blocks the IP addresses and ports of an application predefined by FortiGuard:

● ISDB works by matching traffic to knownIP addresses and portsof categorized services.

● When an application or service is blocked, FortiGate prevents communication bydenying traffic based on its destination IP and port number.

TheConfiguration Revision Historywindow inFortiManagershows that the most recent configuration change (ID 10) was created byscript_managerwith the actionRetrieved.

Sincescript_manageris a system-level script execution user, the IT team needs to findwho actually triggered this script. This can be done by:

● Checking theFortiManager system logsforscript execution events.

● Using thetype=scriptfilter to locate the administrator associated with the script execution.

The FortiGateSSL/SSH inspection profileis configured forFull SSL Inspection, which is necessary to analyze encrypted HTTPS traffic. However, the firewallpolicy is protecting an SSL server (the Linux server hosting the website), and currently, the SSL/SSH profileonly applies to client-side SSL inspection.

To detect HTTPS-based attacks targeting the Linux server:

●FortiGate must act as an SSL intermediaryto inspect encrypted traffic destined for the web server.

● The administratormust upload the SSL certificate of the Linux web serverto FortiGate so that theserver-side SSL inspectioncan decrypt incoming HTTPS traffic before analyzing it.

When FortiGate is operating inproxy modewithfull SSL inspection enabled, it inspects encrypted HTTPS traffic by default onport 443. However, some websites may usenon-standard HTTPS ports(such as 8443), which FortiGate does not inspect unless explicitly configured.

To ensure that FortiGate inspects HTTPS traffic onport 8443, administrators mustmanually add port 8443in theProtocol Port Mappingsection of theSSL/SSH Inspection Profile. This allows FortiGate to treat HTTPS traffic on port 8443 the same as traffic on port 443, enabling proper inspection and enforcement ofFortiGuard category-based web filtering.

TheMulti-Exit Discriminator (MED)is aBGP attributeused to influence the preferred path for incoming traffic from an external autonomous system (AS). The diagram shows that FortiGate_1 advertisesMED 200, while FortiGate_2 advertisesMED 300, meaningthe ISP will prefer the route through FortiGate_1because alower MED is preferredin BGP.

To modify theMED valueon FortiGate_1 for routes advertised to AS 30, the administrator must configure aroute-map-out. A route map canmatch specific routesandset the MED valuebefore sending them to the BGP neighbor.

The MAC addresse0:23:ff:fc:00:86follows the format used inFortiGate High Availability (HA) clusters. When FortiGate devices are in an HA configuration, they usevirtual MAC addressesfor failover and redundancy purposes.

The suspicious packet is related to a cluster that has VDOMs enabled:FortiGate devices withVirtual Domains (VDOMs)enabled use specific MAC address ranges to differentiate HA-related traffic. This MAC address is likely part of that mechanism.

The suspicious packet is related to a cluster with a group-id value lower than 255:FortiGate HA clusters assign virtual MAC addresses based on thegroup ID. The last octet (00:86) corresponds to agroup IDthat isbelow 255, confirming this option.

The exhibit shows anactive-passive HA (high availability) clusterwith two virtual clusters, where FortiGate_A is the primary device for both Core1 and Core2. If the goal is to haveFortiGate_B take over Core2 traffic, itspriority must be higherthan FortiGate_A forVirtual Cluster 2.

Currently, FortiGate_A has a priority of150for Core2, while FortiGate_B has128. IncreasingFortiGate_B’s priority to 200ensures it becomes theprimary for Virtual Cluster 2, taking over the Core2 VDOM traffic while keeping Core1 traffic on FortiGate_A.

Disabling override would prevent forced failovers but wouldn’t change the role distribution. Adjusting the load-balancing method is irrelevant in anactive-passive setup, as it only applies to active-active configurations.

When multiple remote sites connect to thesame hubusingoverlapping subnets, FortiGate needs to determine which route should be used for traffic forwarding. Theroute-overlapsetting in IPsec Phase 2 allows FortiGate to handle this scenario by deciding whether to keep theexisting route(use-old) or replace it with anew route(use-new).

In anECMP (Equal-Cost Multi-Path) routing setup,both routes should be retained and balanced, but FortiGate does not supportECMP directly over overlapping routesin IPsec Phase 2. Instead, an administrator must decide which connection takes precedence usingroute-overlapsettings.

The excessiveDNS log requests with random subdomainssuggest aDNS exfiltration attack, where attackers encode and transmit data via DNS queries. Since this technique can useboth UDP and TLS (DoH - DNS over HTTPS), a comprehensive security approach is needed.

Using anIPS profile with DNS exfiltration-specific signaturesallows FortiGate to:

●Detect and block abnormal DNS query patternsoften used in exfiltration.

●Inspect encrypted DNS (DoH, DoT) trafficif SSL inspection is enabled.

●Identify known exfiltration domains and techniquesbased on FortiGuard threat intelligence.

The diagnose vpn tunnel list name Hub2Spoke1 command output provides key information about the offloading status of an IPsec VPN tunnel to the Network Processing Unit (NPU).

● npu_flag=20:

● This flag indicates that both inbound and outbound IPsec Security Associations (SAs) have been offloaded to the NPU, meaning the VPN traffic is processed in hardware instead of the CPU.

● npu_rgwy=10.10.2.2 and npu_lgwy=10.10.1.1:

● These IPs represent the remote gateway (rgwy) and local gateway (lgwy), confirming that the tunnel is successfully offloaded.

● npu_selid=1:

● This value means the session selector for the NPU offloaded SA is active.

Since both inbound and outbound SAs are offloaded, the administrator can conclude that the FortiGate NPU is handling IPsec encryption and decryption efficiently, reducing CPU load and improving VPN performance.

From theBGP neighbor status output, the key issue is thatBGP is stuck in the "Idle" state, meaning the FortiGate is unable to establish a BGP session with its peer100.65.4.1(Remote AS 65300).

The output also shows:

●"Not directly connected EBGP"→ This means the BGP peer is not on the same subnet, requiring multihop BGP.

●"Update source is Loopback"→ Since a loopback interface is used, FortiGate must be configured to allow BGP neighbors over multiple hops.

To resolve this issue, the administrator must enableebgp-enforce-multihop, which allows BGP sessions to be established even when the neighbors are not directly connected.