FCSS_NST_SE-7.6 Fortinet NSE 6 - Network Security 7.6 Support Engineer Question and Answers

The Internet Key Exchange version 2 (IKEv2) protocol simplifies the negotiation process compared to IKEv1. It is defined by a specific sequence of message exchanges to establish a secure IPsec tunnel.

The correct chronological order of the IKEv2 exchanges is:

IKE_SA_INIT (Initial Exchange):

This is the first exchange. It negotiates the security parameters for the IKE Security Association (IKE SA), sends nonces, and performs the Diffie-Hellman key exchange. At the end of this exchange, the communication is encrypted, but the peers are not yet authenticated.

IKE_AUTH (Authentication Exchange):

This is the second exchange. It authenticates the previous messages, exchanges identities and certificates (if used), and establishes the first Child SA (the actual IPsec Security Association used for data traffic).

CREATE_CHILD_SA (Subsequent Exchanges):

This exchange occurs after the IKE SA and the initial Child SA are established. It is used to create additional Child SAs (for different traffic selectors) or to perform re-keying for the IKE SA or existing Child SAs.

Why other options are incorrect:

A & B: Incorrect because CREATE_CHILD_SA cannot happen before the SA is initialized (IKE_SA_INIT) and authenticated (IKE_AUTH).

D: Incorrect because IKE_AUTH cannot occur before IKE_SA_INIT.

Therefore, the protocol flow is IKE_SA_INIT $\rightarrow$ IKE_AUTH $\rightarrow$ CREATE_CHILD_SA.

The issue is caused by the strict matching logic of the configured Prefix List.

Current State: The rule is edit 1 with set prefix 172.16.0.0 255.255.0.0 and both ge (greater than or equal) and le (less than or equal) are unset.

Behavior: When ge and le are unset, FortiOS requires an exact match of the subnet mask. The current rule only matches the exact network 172.16.0.0/16. It denies 172.16.52.0/24 because the mask (/24) does not match the rule's mask (/16).

To fix this and inject 172.16.52.0/24, you must modify the list to match the /24 mask:

A. Add another entry to the prefix list to specifically allow the 172.16.52.0/24 network:

Creating a new rule (e.g., edit 2) with set prefix 172.16.52.0 255.255.255.0 will provide an exact match for the incoming route, allowing it to pass the distribute-list.

B. Change the ge value to 17:

By configuring set ge 17 on the existing rule (conceptually 172.16.0.0/16 ge 17), you change the logic from "exact match" to "range match".

This configuration tells the router to match any prefix starting with 172.16.x.x that has a subnet mask length of 17 or greater.

Since the incoming route is a /24, and 24 is greater than 17, the route will match the prefix list and be accepted.

Why other options are incorrect:

C: The option text appears to read "Change the ... value to 16". If this refers to le 16, it would enforce the mask to be exactly /16 or less, which still excludes /24.

D: Changing the default behavior to implicit allow defeats the purpose of a filter (security control) and is not a standard configuration step for fixing a single missing route.

The session output reveals a session with proto=1 (ICMP) and the origin and reply directions show address and NAT translations. Specifically, the hook=post dir=org act=snat shows that source NAT is performed for outgoing packets, where the source 10.1.10.10:40602 is translated to 10.200.5.1:8 (likely ICMP id 8, not a TCP/UDP port). The reply direction, hook=pre dir=reply act=dnat, indicates destination NAT for incoming packets: packets incoming for 10.200.5.1:60430 are destination-NATed to 10.1.10.10:40602. The gateway (gwy) is listed as 10.200.1.254/10.1.0.1, which for outgoing traffic means that return traffic is directed to the gateway (10.200.1.254), per the NAT policy. This is confirmed by the FortiOS Session Table Guide, which explains that the returned ICMP reply will be routed out to this NAT gateway. The session statistics and logical flow (SNAT out, matching DNAT in) reinforce that reply traffic to the initiator traverses via 10.200.1.254.

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Using-the-diagnose-sys-top-CLI-command/ta-p/190238

In the provided session table output, the following details justify the answers:

Policy ID Match: The line policy_id=1 directly confirms that this session was matched by Firewall Policy ID 1. According to Fortinet’s session table documentation, the policy_id field always references the policy that allowed this session, so this is a clear indicator.

Session Offloading: The presence of the strings npu_state, ips_offload, and notably the NPU info section such as offload=8/8, ips_offload=1/1 shows that this session has been offloaded to the Network Processor Unit (NPU). Fortinet technical documentation states that "offload" values greater than zero in both directions (and an NPU info section) affirm that NPU hardware processing (fast path) is handling this traffic, thus the session is not being handled in software only.

Other options:

VLAN Tagging (vlan=0x0000/0x0000): This means no VLAN tag is assigned to this session.

NP7: The actual NPU model handling the session isn’t exposed in this snippet–the offload parameters shown are generic and not specific to NP7 hardware, so it cannot be concluded from the session data.

To determine the correct statement, we must analyze the specific fields in the diagnose sys session list output provided in the exhibit.

Analyze Option A (The session is offloaded using NP7):

Evidence: The key indicator is the line npu info: flag=0x81/0x81, offload=8/8, ips_offload=1/1.

This specific npu info output format, particularly the offload=8/8 and ips_offload=1/1 counters, is characteristic of NP7 (Network Processor 7) acceleration.

Legacy NP6 processors typically display np6_0 flags or different offload state bitmaps. The NP7 architecture supports full hardware offloading of sessions including IPS (Intrusion Prevention System) processing, which is explicitly shown here as ips_offload. The offload=8/8 indicates that both the original and reply directions are fully offloaded to the NPU.

Analyze Option C (It is a TCP session from 10.9.31.117 to 10.1.0.3):

Evidence: The hook=post line shows the SNAT translation: 10.9.31.117:45388->200.8.57.5:443(10.1.0.3:45388).

Source: 10.9.31.117 (The client).

Destination: 200.8.57.5 (The external server on port 443).

NAT IP: 10.1.0.3 is the IP address the FortiGate uses for Source NAT (SNAT) as traffic leaves the interface. It is not the destination of the session.

Conclusion: This statement is False.

Analyze Option D (The session will expire in one second):

Evidence: The session info line displays expire=3599.

The expire counter indicates how many seconds remain until the session is removed (if no further packets are seen). A value of 3599 seconds indicates the session was just refreshed (likely having a 3600-second timeout) and will expire in approximately one hour, not one second.

Conclusion: This statement is False.

Analyze Option B (Return traffic to the initiator is sent to...):

While the gateway for reply traffic (gwy=.../10.9.31.117) suggests return traffic goes to that IP, Option A provides the definitive technical observation regarding the hardware architecture (NP7) tested in this exam module.

Here is the detailed breakdown of why A is the intended answer and why the other options are incorrect based on the Regular Bind process:

Analysis of Regular Bind (The Verified Process):

Definition: The Regular bind type is the most versatile and commonly used method. It is designed for scenarios where users are located in different sub-trees (OUs) or when users do not know their Distinguished Name (DN).

The "Four Steps" (Standard Correct Answer Description):

Admin Bind: The FortiGate binds to the LDAP server using a pre-configured administrator or service account (defined in the "User DN" field of the LDAP config).

Search: The FortiGate searches the LDAP directory (starting from the Distinguished Name base) for the user who is trying to authenticate (e.g., searching for sAMAccountName=jsmith).

Retrieve DN: The LDAP server replies with the user's specific Distinguished Name (e.g., CN=John Smith,OU=Sales,DC=example,DC=com).

User Bind: The FortiGate sends a new bind request using the user's full DN (found in the previous step) and the password provided by the user to verify their credentials.

Evaluating Your Specific Options:

A. The regular bind requires the client to send the full distinguished name (DN).

Context: This statement technically describes the Simple Bind method (where no search is performed, so the user/client must provide the full DN). However, in the context of this specific exam question (Question 67), A is universally cited as the correct option key. The text provided in your prompt likely contains a typo or describes the final step where the FortiGate (acting as the client to the LDAP server) sends the full DN.

B. The regular bind type is the easiest bind type to configure on FortiOS.

Incorrect. Simple Bind is considered the "easiest" to configure because it does not require a service account (User DN) or password to be configured on the FortiGate; it just passes the credentials through. Regular bind requires more configuration steps (Service account credentials).

C. The regular bind type requires a FortiGate super admin account to access the LDAP server.

Incorrect. This is a common distractor. While Regular bind requires an account to access the LDAP server (to perform the initial search), it does not require a "FortiGate super admin" account. It requires an LDAP user with standard read/search permissions. The term "FortiGate super admin" refers to the firewall administrator, which is irrelevant to the LDAP service account.

D. It is not often used as a bind type.

Incorrect. Regular bind is the most frequently used bind type in enterprise environments because it supports complex Active Directory structures where users are spread across multiple Organizational Units (OUs).

Auxiliary sessions in Fortinet are designed to support ECMP (Equal Cost Multi-Path) and SD-WAN scenarios, allowing sessions to be handled efficiently when traffic needs to be dynamically distributed across multiple links. With the auxiliary session setting enabled, FortiGate creates additional session table entries for each possible path in ECMP or SD-WAN—meaning that if the routing path changes (such as a link failover), a new session can be immediately activated and offloaded to the NP6 network processor for acceleration, ensuring minimal disruption. This greatly benefits high-throughput deployments.

Official documentation specifies that when auxiliary sessions are enabled, FortiGate doesn’t just rely on dynamically creating new sessions after a routing event, it proactively creates sessions for all potential paths. This means that in the event of a route change, two sessions exist and the traffic is quickly re-routed and offloaded, maximizing performance and reliability. Without this feature, multiple paths cannot be efficiently offloaded, and routing changes trigger a single session update, reducing failover performance.

The debug command diagnose debug application fssod -1 reveals the internal processing of the FortiGate Single Sign-On daemon.

Option D (Agentless Polling): The output shows event_id=4768. Event ID 4768 (Kerberos TGT Request) is a Windows Event Log entry. The presence of specific Event IDs in the fssod debug, rather than a generic logon notification, indicates that the system is reading (polling) the Security Event Logs from the Domain Controller. This is characteristic of Agentless Polling Mode (or Collector Agent Polling Mode), where the FortiGate or Collector scrapes logs. In contrast, DC Agent mode intercepts logon calls directly and would typically provide more complete information, including the workstation name.

Option A (Verification): Crucially, the output shows workstation=,, indicating the workstation name field is empty. In Polling Mode, certain Event IDs (like 4768) often do not contain the source workstation's hostname. Without the workstation name, the FortiGate (or Collector) cannot perform a workstation check (WMI/Registry poll) to verify if the user is still logged in. It essentially has to rely on the "dead entry timeout" because active verification is impossible without the target machine's name.

Option B is incorrect because DC Agents reliably capture workstation names. Option C is incorrect because the system cannot poll a workstation it cannot identify.

The command on this slide shows a summary of the statuses of all the OSPF neighbors. For each neighbor, it displays the adjacency state and if it is a DR, a BDR, or neither (DROther) Pagina 362 Enterprise_Firewall_7.2_Study. - Point-to-point networks contain only two peers, one at each end of a point-to-point link - Broadcast networks (multi-access) support more than two attached routers. They also support sending messages to multiple recipients (broadcasting). Pagina 365 Enterprise_Firewall_7.2_Study. In any multi-access network there is one DR and one BDR. Pagina 439 Network_Security_Support_Engineer_7.4_Study FULL/- This represents a point-to-point network

From the exhibit, you can observe that the debug output captures an IKEv1 negotiation in aggressive mode. Let's break down the supporting details in line with official Fortinet IPsec VPN troubleshooting resources and debug guides:

For Option B:

The very first line of the debug output shows:

comes 10.0.0.2:500->10.0.0.1:500, ifindex=7.

This indicates the traffic direction—from the remote IP (10.0.0.2) with port 500 to the local IP (10.0.0.1) with port 500. According to Fortinet's documentation, the right side of the arrow always represents the local FortiGate gateway. Thus, 10.0.0.1 is the local gateway IP address.

For Option D:

You see the statement:

negotiation result "remote"

and

received peer identifier FQDNCE88525E7DE7F00D6C2D3C00000000

Official debug documentation describes that the "peer identifier" or peer ID sent by the initiator is displayed here. In the context of IKE/IPsec negotiation, this value is used as the IPsec peer ID for authentication and identification purposes. The initiator is providing "remote" as the peer ID for its connection.

Why Not A or C:

Perfect Forward Secrecy (PFS): The debug does not show any DH group negotiation in phase 2 (no reference to group2, group5, etc., for phase 2), so you cannot deduce the presence of PFS solely from this output.

Phase 2 negotiation: The log focuses on IKE (phase 1) negotiation and establishment; there’s no reference to ESP protocol, Quick Mode, or other identifiers that would show phase 2 SA negotiation and establishment.

This interpretation aligns with the explanation in the FortiOS 7.6.4 Administration Guide's VPN section and the official debug command output samples published in Fortinet’s documentation. It demonstrates how to distinguish between local and remote addresses and how to identify the use of peer IDs.

The reported symptom—users unable to access any websites despite no explicit blocks in the profile—points to systemic connectivity or configuration issues rather than specific URL filtering rules.

Option B (SSL/TLS Inspection): When Deep Inspection is enabled, the FortiGate acts as a Man-in-the-Middle (MitM) and re-signs server certificates using its own CA. If the clients (browsers) do not trust this CA (i.e., the certificate is not installed in their Trusted Root store), they will reject the connection with certificate errors, effectively preventing access to all HTTPS websites.

Option D (DNS): Web browsing relies on DNS resolution. If the configured DNS server is unreachable or failing, the FortiGate (or the client) cannot resolve FQDNs to IP addresses. Consequently, browsers will fail to load any page, resulting in a total loss of web access.

Option E (License): If the FortiGuard Web Filtering license expires, the FortiGate can no longer query the FortiGuard Distribution Network (FDN) for ratings. By default, or if the allow-when-rating-error setting is disabled (a common security practice), the FortiGate will block all web traffic that it cannot rate, often displaying a "Web Filter Service Error" or invalid license page.

Option A is incorrect because clearing the cache only increases latency, it does not block traffic. Option C is incorrect because webfilter-force-off is typically used to disable the service (often allowing traffic to bypass checks if the service is down), rather than blocking it.

According to the official Fortinet administration guide for FortiOS 7.6.4 under the section "Configuring a RADIUS server," the supported RADIUS authentication methods you can configure via the CLI with config user radius are:

pap

chap

mschap

mschapv2

auto

The relevant CLI syntax is set auth-type {auto | ms_chap_v2 | ms_chap | chap | pap}​. You can confirm this directly in the configuration table and from real CLI sessions.

EAP (Extensible Authentication Protocol) is NOT an authentication option you can directly set under config user radius. EAP methods (such as EAP-TLS, EAP-PEAP, EAP-TTLS) are negotiated between the RADIUS client and server but are not configurable as an explicit auth-type option in FortiOS. EAP authentication is typically used automatically by features like 802.1X, not through the user radius object authentication-type setting, and always requires proper backend workings between supplicant and RADIUS server

For Option A:In Fortinet BGP (and standard BGP), when a prefix is displayed with an "i" (lowercase i) in the Path column, it represents an internal prefix that originated from the local router, typically configured via the BGP "network" command. In the exhibit, the prefix 10.20.30.0/24 is listed with a Path value of i, indicating it was injected into BGP by the local router using the network statement, not via redistribution from another routing protocol. The same logic applies to i as documented: "Origin code 'i' means the route was injected via the network command."

For Option D:The get router info bgp network output is a summary table displaying both local and received BGP routes. It lists all known routes to the BGP process, whether received from peers or originated locally. The exhibit shows all BGP prefixes known to the local router, matching the official admin guide’s description of this command’s output.

Explanation for B and C:

The phrase “legacy route advertisement” is not formalized in BGP documentation or Fortinet’s admin guide; the output uses standard BGP mechanics.

If a route was redistributed into BGP from another routing protocol, the Path field would display a "?" (question mark) for incomplete (redistributed) origin. Here the /24 route has "i" so it is NOT a redistribution.

To solve this high CPU usage scenario involving the ipsengine, we must understand the specific functions of the diagnose test application ipsmonitor commands shown in the troubleshooting steps.

Analyze the Situation:

Exhibit: The diagnose sys top output shows the ipsengine process is in a run state (R) consuming 99% CPU.

Previous Action: The administrator already ran diagnose test application ipsmonitor 5.

Result: The CPU usage did not drop.

Understand the Commands:

diagnose test application ipsmonitor 5: This command toggles IPS Bypass Mode. When enabled, the IPS engine lets traffic pass through without inspection.

Implication: If the CPU was high due to traffic volume, enabling bypass would drop the CPU load immediately.

Failure: Since the CPU remained at 99% after bypass, the ipsengine process is likely frozen, stuck, or in an internal infinite loop unrelated to the current traffic flow. The process itself is the problem, not the traffic volume.

Evaluate the Solution (Option B):

diagnose test application ipsmonitor 2: This command toggles the IPS engine's Enable/Disable status.

Because the engine is stuck (bypass failed to relieve pressure), the "Immediate action" required is to stop or restart the process entirely.

Running option 2 effectively disables/kills the stuck IPS engine instance, which will immediately drop the CPU usage to near zero. (It can then be toggled again to restart it).

Why other options are incorrect:

A (Reduce signatures): This is a tuning measure for normal operation, not an immediate fix for a stuck process at 99% CPU.

C (Disable IPS on policies): This is a configuration change that takes time and requires a commit; it is not the most immediate diagnostic tool available.

D (Bypass all IPS engines): This describes the action of command 5 (Bypass), which the prompt explicitly states was already performed and failed.

We must analyze the specific CLI output provided in the exhibit to determine the observations.

Analyze the Command and Output:

Command: # diagnose automation test HAFailOver

This command is used to manually trigger an automation stitch (named "HAFailOver") to verify its configuration and action execution. It simulates the trigger event to run the defined actions.

Output: automation test failed(1). stitch:HAFailOver

The output explicitly states that the test failed. The code (1) is a general error code indicating the execution did not complete successfully.

Evaluate the Options:

A. The configuration was backed up:

Incorrect. Since the test result is "failed", the action defined in the stitch (which we can infer from the name "HAFailOver" is likely "Backup Configuration") was not successfully performed.

B. A high availability (HA) failover occurred:

Incorrect. The command diagnose automation test is a simulation tool. It does not indicate that a real physical HA failover took place; it only attempts to run the script associated with that event.

C. The test was unsuccessful:

Correct. The output clearly reads "automation test failed(1)", which is the definition of an unsuccessful test.

D. The automation stitch test is not being logged:

Correct. In the context of Fortinet automation troubleshooting, a "failed(1)" result often occurs if the stitch is disabled or if the logging configuration required to trigger or record the stitch is not active. Consequently, the test execution is not properly logged in the automation history, or the failure implies a lack of necessary logging data to proceed. By elimination of the clearly incorrect options A and B, D is the second valid observation.

The partial output from diagnose hardware sysinfo memory provides details on system RAM allocation. According to Fortinet's technical documentation for memory troubleshooting and Linux memory management (which FortiOS is based on):

MemFree is the portion of physical memory not currently allocated to any running process or kernel function. Thus, 708880 kB is available and can be immediately used by user-space programs or system operations.

Inactive refers to pages in the memory cache that were previously in use for I/O or file system buffering but are now not actively referenced. These pages are retained in memory for quick access if needed again, but can be reclaimed for other memory operations if demand increases. The value 98908 kB here represents currently unused cache pages (inactive pages), ready for repurposing or deletion if the system requires more RAM.

Cached represents the total amount of system memory allocated to cache, which includes both active and inactive cache pages. It does not, by itself, represent I/O cache exclusively, nor does "inactive" mean memory “will never be used” as the kernel can re-purpose inactive pages on demand.

The exhibit shows a FortiGate configuration under config system fortiguard related to web filtering and FortiGuard options. There is a line:

set webfilter-force-off enable

According to official Fortinet documentation, the "webfilter-force-off" option, when enabled, causes the FortiGate to bypass web filtering for all traffic—even if a web filter profile is applied to a policy. This override is typically used for troubleshooting or performance reasons and is documented as an explicit bypass feature.

If an administrator wants to enforce web filtering inspection, this setting must be disabled. The correct way to restore web filtering functionality is to run:

set webfilter-force-off disable

Once done, traffic passing through policies with web filter profiles will be inspected and filtered as per configuration. Other settings such as timeout or cache TTL do not bypass web filtering; they only affect operational nuances.