Intrusion Prevention Systems (IPS) in firewalls follow amulti-step processto detect and mitigate threats. The steps occur in a logical sequence:

1️⃣Step 1: Identifies and Parses Application-Layer Protocols

The firewall firstidentifies the protocol being used(e.g., HTTP, FTP, DNS, SMTP).

Parsing the protocol helps the IPS engineunderstand how the data is structuredand what types of attacks might be embedded.

This step is crucial for detectingprotocol-based attackslike SQL injection or cross-site scripting (XSS).

2️⃣Step 2: Reassembles IP Fragments and TCP Flows

Attackers oftensplit malicious payloads across multiple packetsto evade detection.

The firewallreassembles fragmented packets and TCP flowsto reconstruct the full data stream.

This step is critical for detectingevasion techniques such as fragmented attacks or out-of-order packet attacks.

3️⃣Step 3: Performs Signature Matching

Once the full data stream is reassembled, the IPScompares it against known attack signatures.

Signature matching helps detect:

Malware patterns(e.g., botnets, Trojans).

Exploits targeting vulnerabilitiesin software and operating systems.

Firewalls usepredefined signature databasesthat are regularly updated.

4️⃣Step 4: Performs the Response Action Based on the IPS Profile

If an attack is detected, the firewall takes anaction based on the IPS policy:

Block the traffic(drop malicious packets).

Alert the administrator(generate logs and alerts).

Rate-limit traffic(slow down potential attack sources).

Theresponse mechanism is customizablebased on security requirements.

A screenshot of a computer error message AI-generated content may be incorrect.

POST → Sending Information to the Server

ThePOST methodin HTTP is used to send data to a web server.

Examples include:

Submitting login credentials.

Posting comments or messages on a forum.

Uploading files via web applications.

UnlikeGET, POSThides sensitive information in the request body, making it more secure for transmitting login credentials or personal data.

Internet Access Using a Proxy → Firewall Deployment for Proxy Access

Aproxy serverallows users toaccess the internet through a controlled gateway.

To enforce security policies, afirewall must be deployed between the intranet and the proxy server.

Proxies are used for:

Content filtering(blocking unwanted websites).

Access control(restricting web usage based on user roles).

Anonymization(hiding the user's original IP address).

File Upload/Download Size → Controlling Upload Limits

Firewalls and security devicescan restrict file upload/download sizesto:

Prevent excessive bandwidth usage.

Block potentially malicious file uploads.

Alert and Block Thresholds:

Alert threshold:Logs a warning if a file exceeds a specific size.

Block threshold:Prevents files larger than the configured limit from being uploaded or downloaded.

Comprehensive and Detailed Explanation:

Inbound bandwidth= Trafficenteringthe firewall.

Outbound bandwidth= Trafficleavingthe firewall.

Correct answers:B. Public → Private traffic is controlled by inbound bandwidth.D. Private → Public traffic is controlled by outbound bandwidth.

HCIP-Security References:

Huawei HCIP-Security Guide → Firewall Virtual System Bandwidth Control

Comprehensive and Detailed Explanation:

A Trojan horse is a type of malware that disguises itself as a legitimate applicationto trick users into installing it.

Transmission methods:

A. Exploiting vulnerabilities→ Attackers use system/software vulnerabilities to inject Trojans.

B. Bundled in software→ Trojans are included in cracked software or pirated applications.

C. Downloaded from third-party sites→ Users unknowingly install malware from untrusted sources.

D. Masquerading as useful software→ Fake tools trick users into installation.

Why are all options correct?

All listed methods are common ways Trojans spread.

HCIP-Security References:

Huawei HCIP-Security Guide → Malware & Trojan Horse Attacks

Comprehensive and Detailed Explanation:

Flood attacks (DoS/DDoS) overwhelm network resources, preventing normal users from accessing services.

Correct answers:

A. Exhaust available bandwidth→ Large amounts of traffic saturate the network.

B. Exhaust server-side resources→ High CPU/memory usage causes server crashes.

D. Exhaust network device resources→ Firewalls, routers, and switches become overloaded.

Why is C incorrect?

Controlling host rights is related to hacking, not flooding attacks.

HCIP-Security References:

Huawei HCIP-Security Guide → DoS/DDoS Attack Prevention

Comprehensive and Detailed Explanation:

Network Access Control (NAC) and AAA work together for secure network access.

Key functions:

A. AAA handles user-to-device authentication.

B. NAC handles device-to-server authentication.

C. NAC supports 802.1X, MAC authentication, and Portal authentication.

D. AAA enforces authentication, authorization, and accounting.

Why are all options correct?

Each option correctly describes a function of NAC or AAA.

HCIP-Security References:

Huawei HCIP-Security Guide → NAC & AAA Integration

What is IKE DPD (Dead Peer Detection)?

IKE DPD (Dead Peer Detection)is a mechanism used inIPsec VPNsto check if a remote VPN peer is still reachable.

It allows the firewall to detectlink failuresandautomatically tear down and re-establish IPsec tunnelswhen necessary.

Why is DPD required in this scenario?

The network uses an active/standby link setup:

IPsec Tunnel 1 (Active) → Uses Link 1 (GE0/0/1).

IPsec Tunnel 2 (Standby) → Uses Link 2 (GE0/0/2).

IfLink 1 fails, the firewall must detect the failure andtear down IPsec Tunnel 1before establishingIPsec Tunnel 2 over Link 2.

DPD detects unreachable peersand triggers a failover.

How does IKE DPD work?

DPD periodically sends probes (HELLO messages) to the remote VPN peer.

If no response is received within a timeout period, the firewall assumes the peer is down.

Thefirewall deletes the IPsec tunnel and switches to the backup link.

Why is the answer "dpd" (lowercase)?

The questionexplicitly asks for lowercase letters.

"dpd" (Dead Peer Detection) is the correct technical term in Huawei firewalls and networking standards.

HCIP-Security References:

Huawei HCIP-Security Guide→ IPsec VPN High Availability & DPD

Huawei USG Series Firewall Configuration Guide→ IKE Dead Peer Detection (DPD)

Comprehensive and Detailed Explanation:

Hot standby networkingensureshigh availabilityby keeping a backup firewall ready in case of failure.

Two main modes exist:

Active/Standby Mode→ One firewall is active, and the other remains standby. Configuration is synchronized fromactive → standby.

Load-Sharing Mode→ Both firewallsprocess traffic simultaneously, improving performance.

Why is A false?

InLoad-Sharing Mode, both firewalls are active, butconfiguration synchronization does not cause conflicts. Instead, the firewalls synchronize states properly.

Why is D false?

InLoad-Sharing Mode, configuration is always synchronizedfrom the active firewall to the standby firewall, not the other way around.

HCIP-Security References:

Huawei HCIP-Security Guide → Hot Standby Configuration

Huawei USG Firewalls High Availability Guide