FCSS_NST_SE-7.6 Exam Dumps - Fortinet NSE 6 - Network Security 7.6 Support Engineer

The administrator is running a packet sniffer with the filter ' udp port 500 or udp port 4500 or esp ' . The result is " no output, " even though the VPN is attempting to establish (failing).

A. The VPN is configured to use IKE over TCP:

Standard IPsec IKE negotiation uses UDP port 500 (IKE) and UDP port 4500 (NAT-T).

However, if IKEv2 over TCP (RFC 8229) or Fortinet ' s proprietary IKE over TCP is configured (often used to bypass firewalls that block UDP), the traffic will use TCP (often port 4500 or 443).

The sniffer filter explicitly looks for udp or esp (IP Protocol 50).

If the traffic is encapsulated in TCP, it matches tcp protocol, not udp or esp (raw ESP). Therefore, the sniffer sees zero packets matching the filter.

Why other options are incorrect:

B: esp is a valid argument for diagnose sniffer packet. It is equivalent to filtering for IP protocol 50.

C: If the ISP were blocking traffic, the sniffer (running on the local FortiGate) would still see the outbound packets generated by the FortiGate trying to initiate the connection. " No output " implies the local device isn ' t even generating packets matching that filter.

D: Mismatched IKE versions would still generate IKE negotiation packets (proposals/errors) that would be captured by the sniffer.

The correct answer is D. IKE_AUTH .

The study guide explicitly states:

“IKE_Auth exchange:

• Performs the mutual authentication of two IKE endpoints.

• Configures settings like IP/mask, DNS, and so on.

• Sets up the piggyback of a child SA. Negotiates IP flow and security settings for the IPsec SA.”

It also says:

“By default, a piggyback child (IPsec) SA is negotiated along with the IKEv2 SA during IKE_AUTH. If additional IPsec SAs are needed … they are negotiated during subsequent CREATE_CHILD_SA exchanges.”

Why the other options are wrong:

A. IKE_SA_INIT is incorrect because this exchange negotiates the security settings to protect the IKE traffic, not the first CHILD_SA.

B. INFORMATIONAL is incorrect because it is used to convey control messages between IKE endpoints.

C. CREATE_CHILD_SA is incorrect for the first CHILD_SA, because it is used to create new additional child SAs or rekey existing ones after the initial exchange.

To determine the type of policy route, we must interpret the specific flags and fields visible in the diagnose firewall proute list (or similar kernel table) output provided in the exhibit

Identify Key Indicators:

The most critical field in the output is vwl_service=1(test123).

It also lists vwl_mbr_seq=1 5.

Decode the Terminology:

vwl: This stands for Virtual WAN Link. In FortiOS, " Virtual WAN Link " is the legacy internal name for the SD-WAN feature. Even in newer firmware versions (7.x), the kernel and CLI debugs often still refer to SD-WAN objects as vwl.

vwl_service: This specifically refers to an SD-WAN Rule (also known as an SD-WAN Service). The name (test123) is the name given to that specific SD-WAN rule by the administrator.

Evaluate the Options:

A & D (Regular Policy Route): Standard policy routes (configured under config router policy) do not carry the vwl_service tag. They are typically identified by simple gateway or interface instructions without the SD-WAN service abstraction.

B (ISDB Route): While SD-WAN rules can use the Internet Service Database (ISDB) as a destination, the structure of the route entry shown here—specifically defined by a vwl_service ID—classifies it fundamentally as an SD-WAN rule, regardless of the destination object.

C (An SD-WAN rule): The presence of vwl_service and vwl_mbr_seq (SD-WAN member sequence) definitively identifies this entry as a rule generated by the SD-WAN subsystem.

Conclusion: The output shows a route controlled by the SD-WAN engine (vwl), confirming it is an SD-WAN rule.

The exhibit includes these key debug lines:

start_search_dn-base: ' DC=TAC,DC=ottawa,DC=fortinet,DC=com ' filter:sAMAccountName=jsmith

get_all_dn-Found DN 1:CN=John Smith,CN=Users,DC=TAC,DC=ottawa,DC=fortinet,DC=com

The study guide explains that in regular bind , LDAP authentication has four steps , and that during step 2 , FortiGate searches the LDAP tree to find the user’s DN:

“During the second step, FortiGate does a search query in the LDAP database to find the user’s location—in other words, the user’s DN. If the user is found, the server replies with the user’s DN.”

It also states for the real-time debug of step 2:

“An fnbamd_ldap_build_dn_search_req-base message indicates that FortiGate is performing step two: searching for the user in the LDAP tree. This message includes the base branch (distinguished name setting) and the name of the attribute used to locate the user... If the LDAP server finds the user, the output shows the user’s full DN.”

That directly proves:

D is correct because the debug is showing step 2: Search Request

A is correct because the base DN and found DN are under DC=TAC,DC=ottawa,DC=fortinet,DC=com, which corresponds to the LDAP domain/tree root TAC.ottawa.fortinet.com

Why the other options are wrong:

B is wrong because binding with the user’s credentials is step 3 , not the step shown here. The study guide says: “Step 3 – Bind user credentials” and shows that this happens later with fnbamd_ldap_build_userbind_req / __ldap_build_bind_req-Binding to ' CN=John Smith... '

C is wrong because collecting user group information is step 4 , not the step shown in the exhibit. The study guide says: “The last step is to get the user group information” and shows step 4 with Attr query / memberOf search