pfSense Interview Questions

Checkout Vskills Interview questions with answers in pfSense to prepare for your next job role. The questions are submitted by professionals to help you to prepare for the Interview.

Q.1 What is pfSense?

pfSense is an open-source firewall and router software based on FreeBSD. It provides advanced network security features, including packet filtering, VPN support, and traffic shaping.

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Q.2 How do you configure a basic firewall rule in pfSense?

Go to "Firewall" > "Rules," select the interface, click "Add," specify the rule parameters (source, destination, port, action), and then apply the changes.

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Q.3 What is the difference between “pass” and “block” actions in firewall rules?

The “pass” action allows traffic that matches the rule, while the “block” action denies traffic that matches the rule.

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Q.4 How does pfSense handle NAT (Network Address Translation)?

pfSense handles NAT by translating private IP addresses to a public IP address for outgoing traffic and vice versa. Configuration can be done under "Firewall" > "NAT."

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Q.5 What is a "Floating Rule" in pfSense?

Floating rules in pfSense apply to multiple interfaces or traffic directions and are processed before interface-specific rules. They are used for more complex scenarios like multi-interface setups.

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Q.6 How do you configure VPN in pfSense?

Configure VPN by going to "VPN" and selecting the desired VPN type (e.g., OpenVPN, IPsec). Follow the setup wizard or configure manually by specifying server settings, authentication methods, and client configuration.

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Q.7 What is the purpose of the “Dashboard” in pfSense?

The Dashboard provides a high-level overview of system status, including network traffic, CPU usage, memory usage, and firewall logs, allowing for quick monitoring and management.

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Q.8 How do you set up load balancing in pfSense?

Set up load balancing by going to "Firewall" > "Rules," adding a rule with a load balancer pool, and configuring the pool under "Services" > "Load Balancer."

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Q.9 What is a "State Table," and why is it important?

The state table maintains a record of active connections and their states. It is crucial for tracking traffic flow and enforcing firewall rules based on connection states.

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Q.10 How do you perform a basic pfSense system backup and restore?

Perform a backup by going to "Diagnostics" > "Backup & Restore," selecting the backup options, and saving the configuration file. Restore by uploading the backup file in the same section.

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Q.11 What is “Traffic Shaping” in pfSense?

Traffic shaping in pfSense is used to manage bandwidth usage and prioritize network traffic. It helps in controlling bandwidth allocation and ensuring fair usage among users.

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Q.12 How do you configure DNS in pfSense?

Configure DNS by going to "System" > "General Setup," entering DNS server IP addresses, and specifying DNS servers under "DNS Resolver" or "DNS Forwarder."

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Q.13 What are “Aliases” in pfSense, and how are they used?

Aliases are shorthand names for IP addresses, networks, or ports, simplifying firewall rule creation. They are managed under "Firewall" > "Aliases."

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Q.14 How do you configure port forwarding in pfSense?

Configure port forwarding under "Firewall" > "NAT" > "Port Forward." Add a new rule specifying the external and internal ports, IP addresses, and associated NAT rules.

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Q.15 What is “pfBlockerNG,” and how is it used in pfSense?

pfBlockerNG is a package that enhances pfSense by blocking unwanted IP addresses and domains, providing protection against malware, ads, and trackers.

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Q.16 How do you manage firewall logs in pfSense?

View firewall logs under "Status" > "System Logs" > "Firewall." Configure log settings under "System" > "Advanced" > "Logging" to manage logging behavior.

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Q.17 What is “High Availability” in pfSense, and how is it configured?

High Availability in pfSense ensures uninterrupted service by setting up a pair of pfSense firewalls in a failover configuration. Configure using CARP (Common Address Redundancy Protocol) under "System" > "High Availability."

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Q.18 How do you configure a VLAN in pfSense?

Configure VLANs by going to "Interfaces" > "Assignments," adding a new VLAN, specifying VLAN tag and parent interface, and then assigning it to an interface.

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Q.19 What is “Captive Portal,” and how is it used in pfSense?

Captive Portal is used to control and authenticate access to a network, often used in public Wi-Fi hotspots. Configure under "Services" > "Captive Portal."

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Q.20 How do you troubleshoot network issues in pfSense?

Troubleshoot by using tools available in pfSense such as ping, traceroute, and packet capture (under "Diagnostics" > "Ping," "Traceroute," and "Packet Capture") to diagnose network connectivity and performance issues.

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Q.21 What is the purpose of the “Gateways” feature in pfSense?

The "Gateways" feature is used to manage and configure routes for outgoing traffic. It allows setting up multiple gateways for failover or load balancing.

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Q.22 How do you configure IPv6 in pfSense?

Configure IPv6 under "System" > "General Setup" by entering IPv6 DNS servers and enabling IPv6 support. Assign IPv6 addresses to interfaces under "Interfaces" > [Interface Name].

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Q.23 What is the “Dynamic DNS” feature in pfSense?

Dynamic DNS allows pfSense to update DNS records automatically when the IP address of the router changes, ensuring remote access to network services via a consistent domain name.

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Q.24 How does pfSense handle VPN client connections?

pfSense manages VPN client connections through the VPN configuration menu, where you set up client-specific settings for various VPN types (e.g., OpenVPN, IPsec) and assign them to users.

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Q.25 What are “IPsec” and “OpenVPN” in pfSense, and how do they differ?

IPsec is a protocol suite for securing IP communications by authenticating and encrypting each IP packet, while OpenVPN is an open-source VPN software that uses SSL/TLS for encryption and is more flexible in configuration.

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Q.26 How do you configure QoS (Quality of Service) in pfSense?

Configure QoS under "Firewall" > "Traffic Shaper," where you can create rules and limits for different types of traffic to prioritize critical applications and manage bandwidth usage.

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Q.27 What is “Suricata,” and how does it integrate with pfSense?

Suricata is an open-source IDS/IPS engine that can be installed on pfSense to provide intrusion detection and prevention by analyzing network traffic for suspicious activity.

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Q.28 How do you create a VPN site-to-site connection with pfSense?

Set up a site-to-site VPN under "VPN" > "IPsec" or "OpenVPN," configure phase 1 and phase 2 settings, and exchange keys with the remote site to establish a secure connection between two networks.

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Q.29 What are “Routing Tables” in pfSense, and how do you manage them?

Routing tables in pfSense manage how network traffic is directed based on destination IP addresses. You can view and manage routing tables under "System" > "Routing."

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Q.30 How do you set up Multi-WAN in pfSense?

Configure Multi-WAN by adding multiple WAN interfaces under "Interfaces" > "Assignments," and then set up load balancing or failover rules under "System" > "Routing."

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Q.31 What is the “pfSense Package Manager,” and how is it used?

The Package Manager in pfSense allows you to install and manage additional software packages that extend pfSense functionality, such as firewall enhancements or monitoring tools.

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Q.32 How do you secure access to the pfSense web interface?

Secure access by changing the default admin password, enabling HTTPS, restricting access to specific IP addresses, and using strong authentication methods.

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Q.33 What are “Interface Groups” in pfSense, and when would you use them?

Interface Groups are used to manage multiple interfaces collectively for firewall rules or routing. They are useful when you want to apply rules or configurations to a group of interfaces rather than individually.

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Q.34 How do you manage system updates and upgrades in pfSense?

Manage updates under "System" > "Firmware." You can check for updates, upgrade the system, and review changelogs to ensure the system is up to date.

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Q.35 What is “Snort,” and how does it integrate with pfSense?

Snort is an open-source network intrusion detection and prevention system that can be installed on pfSense to monitor and analyze network traffic for suspicious activities and threats.

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Q.36 How do you handle network address changes in pfSense?

Handle address changes by updating interface configurations under "Interfaces," adjusting NAT and firewall rules as needed, and ensuring routing tables are updated.

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Q.37 What is “RADIUS,” and how can it be used with pfSense?

RADIUS (Remote Authentication Dial-In User Service) is used for centralized authentication and authorization. pfSense can integrate with RADIUS servers for user authentication in VPN or Captive Portal setups.

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Q.38 How do you set up DNS forwarding in pfSense?

Set up DNS forwarding under "Services" > "DNS Forwarder" or "DNS Resolver." Configure the DNS server addresses and enable forwarding to handle DNS queries from the network.

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Q.39 What is the “DHCP Relay” feature in pfSense?

DHCP Relay forwards DHCP requests from clients on one network segment to a DHCP server on another segment. Configure it under "Services" > "DHCP Relay."

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Q.40 How do you implement redundancy and failover in pfSense?

Implement redundancy using CARP (Common Address Redundancy Protocol) for high availability, and configure failover by setting up multiple WAN connections with failover rules under "System" > "Routing."

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Q.41 What are “States” in pfSense, and why are they important?

States refer to the active connections tracked by pfSense's firewall. They are important for maintaining connection integrity and ensuring that traffic is allowed based on connection state.

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Q.42 How do you configure high-availability using CARP in pfSense?

Configure CARP by setting up a virtual IP under "Firewall" > "Virtual IPs," configuring CARP on both firewalls, and synchronizing configuration settings to ensure failover.

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Q.43 What is “Port Knocking,” and how can it be implemented in pfSense?

Port Knocking is a security technique that hides open ports behind a sequence of network requests. Implement it in pfSense using custom scripts or firewall rules to detect the correct sequence.

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Q.44 How does pfSense handle logging and monitoring?

pfSense handles logging and monitoring through the "Status" > "System Logs" section and can integrate with external log management tools for detailed analysis and alerting.

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Q.45 What is the role of “DNS Resolver” in pfSense, and how does it differ from “DNS Forwarder”?

The DNS Resolver provides direct DNS resolution, while the DNS Forwarder passes queries to upstream DNS servers. The Resolver is more flexible and supports DNSSEC and DNS over TLS.

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Q.46 How can you configure a captive portal for guest network access in pfSense?

Configure a Captive Portal under "Services" > "Captive Portal," set up authentication methods and portal pages, and apply it to the appropriate interface or network segment.

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Q.47 What is the function of the “Traffic Shaper Wizard” in pfSense?

The Traffic Shaper Wizard helps configure Quality of Service (QoS) by creating rules and queues to prioritize network traffic and manage bandwidth allocation automatically.

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Q.48 How do you configure pfSense to use external NTP servers?

Configure external NTP servers under "System" > "General Setup" by entering the NTP server addresses in the "NTP Servers" field.

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Q.49 What are “Firewall Aliases,” and how do they simplify rule management?

Aliases are placeholders for IP addresses, networks, or ports that simplify rule management by allowing the use of descriptive names instead of individual IP addresses or ports.

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Q.50 How do you secure a pfSense installation from potential threats?

Secure pfSense by keeping the system updated, using strong passwords, enabling HTTPS for the web interface, restricting access to management interfaces, and employing intrusion detection systems.

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Q.51 What is “Gateway Group” in pfSense, and how is it used for load balancing?

A Gateway Group is used to group multiple gateways for load balancing or failover. Configure it under "System" > "Routing" to distribute traffic across multiple WAN connections.

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Q.52 How can pfSense be integrated with Active Directory for user authentication?

Integrate with Active Directory under "System" > "User Manager" > "Authentication Servers," configure LDAP settings, and set up user and group mappings for authentication.

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Q.53 What is “Proxy ARP,” and how is it configured in pfSense?

Proxy ARP allows pfSense to respond to ARP requests on behalf of hosts on different subnets. Configure it under "Interfaces" by enabling Proxy ARP for the desired interface.

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Q.54 How do you manage pfSense firewall rules using the “Rule Scheduler”?

The Rule Scheduler allows scheduling firewall rules to be enabled or disabled at specific times. Configure it under "Firewall" > "Scheduler" to create and manage scheduled rules.

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Q.55 What are “Packet Capture” tools in pfSense used for, and how do you access them?

Packet Capture tools are used for analyzing network traffic and troubleshooting issues. Access them under "Diagnostics" > "Packet Capture" to capture and analyze packets.

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Q.56 How do you configure logging and alerts for VPN connections in pfSense?

Configure VPN logging under "Status" > "System Logs" > "VPN" to monitor VPN connections and set up alerts by configuring log settings and integrating with monitoring tools.

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Q.57 What is “State Table Overflow,” and how can you prevent it?

State Table Overflow occurs when the number of tracked connections exceeds the system's capacity. Prevent it by optimizing firewall rules, increasing state table size, or upgrading hardware.

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Q.58 How do you implement SSL/TLS for securing web access to pfSense?

Implement SSL/TLS by configuring HTTPS under "System" > "Advanced" > "Admin Access," uploading a valid SSL certificate, and enabling HTTPS access to the pfSense web interface.

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Q.59 What is the function of the “System Patches” feature in pfSense?

The System Patches feature allows applying security and bug fixes by installing patches from the pfSense repository to maintain system stability and security.

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Q.60 How do you set up a VPN client connection for remote access in pfSense?

Set up a VPN client by configuring the client settings under "VPN" > "OpenVPN" or "IPsec," entering server details, authentication methods, and exporting the client configuration.

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