--- name: configuring-pfsense-firewall-rules description: 'Configures pfSense firewall rules, NAT policies, IPsec/OpenVPN tunnels, and traffic shaping to enforce network segmentation and control traffic between zones such as DMZ, internal, guest, and IoT. Use when deploying a pfSense perimeter or internal firewall, setting up port-forwarding NAT, configuring site-to-site or remote-access VPNs, or applying QoS/bandwidth policies. ' domain: cybersecurity subdomain: network-security tags: - network-security - pfsense - firewall - nat - network-segmentation version: '1.0' author: mahipal license: Apache-2.0 nist_csf: - PR.IR-01 - DE.CM-01 - ID.AM-03 - PR.DS-02 mitre_attack: - T1071.001 - T1095 - T1572 - T1571 - T1041 --- # Configuring pfSense Firewall Rules ## When to Use - Deploying a perimeter or internal firewall to segment and protect network zones (DMZ, internal, guest, IoT) - Creating granular access control rules to restrict traffic between VLANs and network segments - Configuring NAT rules for port forwarding to internal services exposed to the internet - Setting up site-to-site or remote access VPN tunnels using IPsec or OpenVPN - Implementing traffic shaping and bandwidth management for quality-of-service requirements **Do not use** as a substitute for host-based firewalls on individual systems, for SSL/TLS deep packet inspection without dedicated hardware acceleration, or as the sole security control without complementary IDS/IPS. ## Prerequisites - pfSense 2.7+ installed on dedicated hardware or virtual machine with at least two network interfaces - Access to the pfSense WebConfigurator (default: https://192.168.1.1) - Network topology diagram showing all interfaces, VLANs, and desired traffic flow - DNS and DHCP configuration planned for each network zone - Understanding of TCP/IP, NAT, and stateful firewall concepts ## Workflow ### Step 1: Configure Network Interfaces and VLANs Access the pfSense WebConfigurator and define interfaces: ``` Navigate: Interfaces > Assignments WAN Interface (igb0): - Type: DHCP or Static IP from ISP - Block private networks: Enabled - Block bogon networks: Enabled LAN Interface (igb1): - IPv4: 10.10.1.1/24 - Description: CORPORATE_LAN Create VLANs: Navigate: Interfaces > VLANs > Add - VLAN 10 on igb1: DMZ (10.10.10.1/24) - VLAN 20 on igb1: SERVERS (10.10.20.1/24) - VLAN 30 on igb1: GUEST (10.10.30.1/24) - VLAN 40 on igb1: IOT (10.10.40.1/24) Assign VLANs: Navigate: Interfaces > Assignments > Add each VLAN Enable each interface and assign the gateway IP ``` ### Step 2: Configure DHCP and DNS for Each Zone ``` Navigate: Services > DHCP Server CORPORATE_LAN (10.10.1.0/24): Range: 10.10.1.100 - 10.10.1.200 DNS: 10.10.20.10 (internal DNS server) Gateway: 10.10.1.1 DMZ (10.10.10.0/24): Range: 10.10.10.100 - 10.10.10.200 DNS: 10.10.20.10 Gateway: 10.10.10.1 GUEST (10.10.30.0/24): Range: 10.10.30.100 - 10.10.30.200 DNS: 1.1.1.1, 8.8.8.8 (public DNS only) Gateway: 10.10.30.1 Navigate: Services > DNS Resolver Enable DNS Resolver on all interfaces except GUEST Enable DNSSEC Configure forwarding to upstream DNS servers ``` ### Step 3: Create Firewall Rule Aliases ``` Navigate: Firewall > Aliases RFC1918_Networks: Type: Network Values: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 WebPorts: Type: Port Values: 80, 443 ManagementPorts: Type: Port Values: 22, 3389, 5900 CriticalServers: Type: Host Values: 10.10.20.10, 10.10.20.11, 10.10.20.12 BlockedCountries: Type: URL Table URL: https://www.ipdeny.com/ipblocks/data/aggregated/cn-aggregated.zone Update: 24 hours ``` ### Step 4: Implement Firewall Rules by Zone ``` Navigate: Firewall > Rules === WAN Rules === # Block all inbound by default (implicit deny) # Allow established/related traffic (automatic in pfSense stateful mode) # Allow inbound to DMZ web server (via NAT) Action: Pass | Interface: WAN | Protocol: TCP Source: any | Destination: WAN Address | Port: 80, 443 Description: Allow HTTP/HTTPS to DMZ web server === LAN Rules === # Allow LAN to access internal servers Action: Pass | Interface: LAN | Protocol: TCP Source: LAN net | Destination: SERVERS net | Port: WebPorts, 3306, 5432 Description: Allow LAN to internal web and database servers # Allow LAN to internet Action: Pass | Interface: LAN | Protocol: any Source: LAN net | Destination: ! RFC1918_Networks Description: Allow LAN to internet (block inter-VLAN via RFC1918 exclusion) # Block LAN to IoT (explicit deny before implicit allow) Action: Block | Interface: LAN | Protocol: any Source: LAN net | Destination: IOT net Description: Block direct LAN to IoT communication === DMZ Rules === # Allow DMZ web servers to query internal DNS Action: Pass | Interface: DMZ | Protocol: TCP/UDP Source: DMZ net | Destination: 10.10.20.10 | Port: 53 Description: Allow DMZ DNS queries to internal resolver # Allow DMZ to internet for updates only Action: Pass | Interface: DMZ | Protocol: TCP Source: DMZ net | Destination: any | Port: 80, 443 Description: Allow DMZ outbound HTTP/HTTPS for updates # Block all other DMZ traffic Action: Block | Interface: DMZ | Protocol: any Source: DMZ net | Destination: any Description: Default deny for DMZ === GUEST Rules === # Allow guest to internet only (DNS and web) Action: Pass | Interface: GUEST | Protocol: TCP/UDP Source: GUEST net | Destination: ! RFC1918_Networks | Port: 53, 80, 443 Description: Allow guest internet access only # Block all guest to internal Action: Block | Interface: GUEST | Protocol: any Source: GUEST net | Destination: RFC1918_Networks Description: Block guest access to all internal networks === IOT Rules === # Allow IoT to specific cloud endpoints Action: Pass | Interface: IOT | Protocol: TCP Source: IOT net | Destination: ! RFC1918_Networks | Port: 443, 8883 Description: Allow IoT HTTPS and MQTT to cloud # Block IoT inter-device communication Action: Block | Interface: IOT | Protocol: any Source: IOT net | Destination: IOT net Description: Prevent IoT lateral movement # Block IoT to all internal networks Action: Block | Interface: IOT | Protocol: any Source: IOT net | Destination: RFC1918_Networks Description: Block IoT access to internal ``` ### Step 5: Configure NAT Rules ``` Navigate: Firewall > NAT > Port Forward # Web server in DMZ Interface: WAN | Protocol: TCP Destination: WAN address | Port: 443 Redirect target IP: 10.10.10.50 | Port: 443 NAT Reflection: Enable Description: HTTPS to DMZ web server # SSH jump host (non-standard port) Interface: WAN | Protocol: TCP Destination: WAN address | Port: 2222 Redirect target IP: 10.10.20.11 | Port: 22 Description: SSH to internal jump host via port 2222 Navigate: Firewall > NAT > Outbound Mode: Hybrid Outbound NAT # Add rule for DMZ servers to use a dedicated public IP Interface: WAN | Source: 10.10.10.0/24 Translation Address: Description: DMZ outbound NAT via dedicated IP ``` ### Step 6: Enable Logging and Monitoring ``` Navigate: Status > System Logs > Settings Remote Logging: Enable Remote log servers: 10.10.20.15:514 (Syslog/SIEM) Log firewall default blocks: Enabled Navigate: Firewall > Rules Enable logging on critical rules: - All BLOCK rules - WAN inbound PASS rules - Inter-VLAN PASS rules Navigate: Diagnostics > pfTop Monitor real-time connection states and bandwidth usage Install pfBlockerNG package: Navigate: System > Package Manager > Available Packages Install pfBlockerNG-devel Configure IP blocklists (Spamhaus DROP, Emerging Threats) Configure DNSBL for malware domain blocking ``` ### Step 7: Backup and Test Configuration ```bash # Export configuration backup Navigate: Diagnostics > Backup & Restore Download XML configuration file # Test rules from each zone # From LAN: curl -I https://10.10.20.10 # Should succeed (LAN to SERVERS) curl -I https://10.10.40.5 # Should fail (LAN to IOT blocked) # From GUEST: curl -I https://www.google.com # Should succeed (internet) curl -I https://10.10.20.10 # Should fail (guest to internal blocked) # From DMZ: nslookup google.com 10.10.20.10 # Should succeed (DNS allowed) ssh 10.10.1.50 # Should fail (DMZ to LAN blocked) # Verify logging Navigate: Status > System Logs > Firewall Check that blocked and passed traffic is logging correctly # Schedule automated config backups Navigate: Diagnostics > AutoConfigBackup Enable automatic backups to Netgate cloud or local storage ``` ## Key Concepts | Term | Definition | |------|------------| | **Stateful Firewall** | Firewall that tracks the state of network connections and automatically allows return traffic for established sessions without explicit rules | | **Alias** | Named group of IP addresses, networks, or ports in pfSense that simplifies rule management and improves readability | | **NAT (Network Address Translation)** | Translation of IP addresses between internal and external networks, including port forwarding for inbound access to internal services | | **Floating Rules** | pfSense rules that apply across multiple interfaces simultaneously, processed before per-interface rules | | **pfBlockerNG** | pfSense package that integrates IP reputation blocklists and DNS-based blocklists for automated threat blocking | | **Rule Processing Order** | pfSense evaluates rules top-to-bottom within each interface tab; first match wins, and unmatched traffic is blocked by default | ## Tools & Systems - **pfSense 2.7+**: Open-source firewall and router platform based on FreeBSD with web-based management and extensive package ecosystem - **pfBlockerNG**: IP and DNS blocklist package for automated threat intelligence integration - **Snort/Suricata packages**: IDS/IPS integration available as pfSense packages for inline traffic inspection - **OpenVPN/IPsec**: Built-in VPN implementations for site-to-site and remote access connectivity - **Netgate AutoConfigBackup**: Cloud-based configuration backup service for pfSense disaster recovery ## Common Scenarios ### Scenario: Segmenting a Small Business Network with pfSense **Context**: A medical practice needs to segment its network to meet HIPAA requirements. They have a single internet connection, an electronic health records (EHR) server, staff workstations, a guest WiFi network, and medical IoT devices (vitals monitors, imaging equipment). Budget constraints require an open-source solution. **Approach**: 1. Deploy pfSense on a Netgate 4100 appliance with four physical interfaces (WAN, LAN, DMZ, MGMT) 2. Create VLANs for staff (VLAN 10), EHR servers (VLAN 20), guest WiFi (VLAN 30), and medical devices (VLAN 40) 3. Configure strict rules: staff VLAN can access EHR servers on HTTPS only; medical devices can communicate only with the EHR server on specific ports; guest WiFi gets internet-only access with no internal routing 4. Enable pfBlockerNG with healthcare-specific threat feeds and malware domain blocking 5. Configure outbound NAT to prevent internal IP addresses from leaking to the internet 6. Enable comprehensive logging and forward all firewall logs to a SIEM via syslog 7. Set up automated configuration backups and document the rule base for audit compliance **Pitfalls**: - Creating rules that are too permissive ("allow any any") instead of specific port-based rules - Forgetting the rule processing order -- placing a broad PASS rule above a specific BLOCK rule - Not enabling logging on critical rules, making incident investigation impossible - Allowing IoT devices unrestricted internet access, creating potential data exfiltration paths ## Output Format ``` ## pfSense Firewall Configuration Report **Device**: pfSense 2.7.2 on Netgate 4100 **Interfaces**: WAN (igb0), LAN (igb1), DMZ (igb2), MGMT (igb3) **VLANs**: 4 configured (Staff, Servers, Guest, IoT) **Total Rules**: 28 active rules across all interfaces ### Rule Summary by Interface | Interface | Pass Rules | Block Rules | Logging Enabled | |-----------|-----------|-------------|-----------------| | WAN | 2 | 1 (default) | Yes | | LAN | 4 | 2 | Yes (blocks) | | DMZ | 3 | 1 (default) | Yes | | GUEST | 1 | 2 | Yes | | IOT | 1 | 3 | Yes | ### Security Controls - pfBlockerNG: 12 IP blocklists + DNSBL enabled - Snort IDS: Running on WAN and LAN interfaces - VPN: OpenVPN remote access configured with MFA - Logging: All traffic forwarded to SIEM (10.10.20.15) ``` --- Source attribution: mukul975 Original project: https://github.com/mukul975/Anthropic-Cybersecurity-Skills/blob/54a798831d2266a3ca61ce68a7acb80b81160d57/skills/configuring-pfsense-firewall-rules/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. # Mega AI Hub resource metadata Creator / publisher: mukul975 Original project: https://github.com/mukul975/Anthropic-Cybersecurity-Skills/blob/54a798831d2266a3ca61ce68a7acb80b81160d57/skills/configuring-pfsense-firewall-rules/SKILL.md Attribution basis: Source repository record Fields of work: Operations Roles: IT Operations Specialties: Specialty not specified Tools: Pfsense Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: f7ede9358003034d19c888243b9d0d4644157a4930349e406d04050bce9e2042