Network Security Policy Template

## Why Network Security Matters

Network security is the frontline defense protecting your organization's most critical assets—customer data, intellectual property, financial systems, and operational infrastructure. A single network breach can cost millions in recovery, regulatory fines, and reputational damage.

Consider the 2017 Equifax breach: Attackers exploited a single unpatched network vulnerability, compromising 147 million records and resulting in $1.4 billion in costs. Or the 2021 Colonial Pipeline attack where inadequate network segmentation allowed ransomware to spread from IT systems to operational technology, shutting down fuel delivery across the Eastern United States for six days.

These aren't isolated incidents. According to IBM's 2024 Cost of a Data Breach Report, the average cost of a breach is $4.88 million, with network vulnerabilities accounting for 15% of all breaches. Meanwhile, Verizon's 2024 Data Breach Investigations Report found that 60% of breaches involved network-level attacks.

Effective network security isn't just about firewalls—it's a comprehensive framework of technologies, policies, and practices that work together to:

**Prevent Unauthorized Access:**

- Control who can connect to your network

- Authenticate users and devices before granting access

- Segment network zones to limit lateral movement

- Enforce least-privilege access principles

**Detect Threats and Anomalies:**

- Monitor network traffic for suspicious patterns

- Identify malware command-and-control communications

- Detect data exfiltration attempts

- Alert security teams to potential compromises

**Respond to Security Incidents:**

- Isolate affected network segments

- Preserve evidence for forensic analysis

- Restore services while maintaining security

- Learn from incidents to prevent recurrence

**Maintain Compliance:**

- Meet regulatory requirements (PCI-DSS, HIPAA, GDPR)

- Pass security audits and assessments

- Demonstrate due diligence to stakeholders

- Protect against legal liability

## Core Network Security Components

### 1. Firewall Architecture and Rules

Firewalls are the foundation of network security, controlling traffic flow between network zones based on defined security rules.

**Firewall Types:**

**Stateful Inspection Firewalls:**

Track the state of network connections (new, established, related) and make decisions based on context, not just individual packets. Most enterprise firewalls (Palo Alto, Fortinet, Cisco ASA) use stateful inspection.

Example Rule Logic:

- Allow outbound HTTPS from internal network to internet (new connections)

- Automatically allow return traffic for established connections

- Block unsolicited inbound traffic (not related to existing connections)

**Next-Generation Firewalls (NGFW):**

Add application awareness, intrusion prevention, and advanced threat detection. Can identify applications regardless of port (detecting Dropbox on port 443 vs. legitimate HTTPS).

**Web Application Firewalls (WAF):**

Protect web applications from attacks like SQL injection, cross-site scripting, and application-layer DDoS. Deployed in front of web servers.

**Firewall Rule Best Practices:**

**1. Default Deny Posture:**

Block everything by default, then create explicit allow rules for required traffic. This "whitelist" approach ensures that only known-good traffic flows.

**2. Rule Ordering Matters:**

Firewalls process rules top-to-bottom, stopping at the first match. Place more specific rules before general rules.

Example Rule Order:

1. Block known malicious IPs (threat intelligence feeds)

2. Allow specific required services (database access from app servers)

3. Allow general services (HTTP/HTTPS outbound)

4. Log and deny everything else (catch-all rule)

**3. Document Every Rule:**

Include business justification, requestor, and review date. Undocumented rules accumulate over time, creating security gaps and compliance issues.

**4. Regular Rule Review:**

Audit firewall rules quarterly to remove obsolete entries. Many organizations find 20-40% of firewall rules are unused "zombie rules" that increase attack surface.

**5. Logging and Monitoring:**

Log denied traffic to identify attack patterns and troubleshoot connectivity issues. Log allowed traffic for forensics and compliance.

### 2. Virtual Private Networks (VPNs)

VPNs create encrypted tunnels over untrusted networks, protecting data confidentiality and integrity.

**VPN Types:**

**Remote Access VPN:**

Individual users connect from home/travel to corporate network. Common solutions include Cisco AnyConnect, Palo Alto GlobalProtect, Fortinet FortiClient.

Requirements:

- Multi-factor authentication (MFA) required before connection

- Endpoint security validation (antivirus updated, OS patched)

- Full-tunnel or split-tunnel configuration (policy decision)

- Session timeout after 8-12 hours of inactivity

- Automatic disconnect when endpoint leaves trusted network

**Site-to-Site VPN:**

Connect entire networks (branch offices to headquarters, cloud to on-premises). Typically use IPsec protocol.

Use Cases:

- Branch office connectivity without dedicated circuits

- Secure cloud connectivity (AWS, Azure, Google Cloud)

- Partner network integration

- Disaster recovery site connectivity

**Full-Tunnel vs. Split-Tunnel:**

**Full-Tunnel VPN:**

All user traffic routes through corporate network, even internet browsing. Provides maximum control and visibility but increases bandwidth costs and can slow user experience.

When to Use:

- High-security environments (financial services, healthcare)

- Regulatory requirements mandate traffic inspection

- Small user base with adequate bandwidth

**Split-Tunnel VPN:**

Only corporate traffic goes through VPN; internet traffic routes directly from user's location. Reduces bandwidth costs but limits visibility.

When to Use:

- Large remote workforce (bandwidth constraint)

- Cloud-first environment (most apps are SaaS)

- Combined with cloud security services (Zscaler, Cloudflare Access)

**Modern Alternative: Zero Trust Network Access (ZTNA):**

Instead of traditional VPN, ZTNA solutions (Zscaler Private Access, Cloudflare Access, Palo Alto Prisma Access) provide application-level access without putting users "on the network."

Advantages:

- Reduced attack surface (no network access, only app access)

- Better user experience (direct cloud connectivity)

- Improved security (continuous verification, context-aware access)

### 3. Wireless (Wi-Fi) Security

Wireless networks extend your attack surface beyond physical boundaries, requiring special security considerations.

**Wireless Encryption Standards:**

**WPA3-Enterprise (Current Standard):**

- 192-bit encryption for high-security environments

- Protected Management Frames (prevents deauth attacks)

- Individual data encryption per client

- Required for new deployments in 2024+

**WPA2-Enterprise (Minimum Acceptable):**

- 802.1X authentication with RADIUS server

- Individual user credentials (not shared password)

- AES encryption

- Acceptable for existing deployments being migrated to WPA3

**NEVER Use WPA2-PSK (Pre-Shared Key) or WEP:**

Shared passwords can be captured and cracked. WEP is trivially broken in minutes.

**Wireless Network Segmentation:**

**Corporate SSID:**

- WPA3-Enterprise with 802.1X authentication

- Full network access after authentication

- Limited to company-owned devices

- Integrated with directory services (Active Directory, Azure AD)

**Guest SSID:**

- Separate VLAN with internet-only access

- No access to corporate resources

- Captive portal for acceptable use agreement

- Bandwidth limits and content filtering

- Automatic DHCP assignment from isolated subnet

**IoT/Device SSID:**

- For smart TVs, printers, building automation

- Certificate-based authentication or MAC filtering

- Restricted access to required services only

- Monitored for unusual traffic patterns

**Wireless Security Best Practices:**

1. **Hide SSID Broadcast?** No—it provides minimal security and breaks some clients. Focus on strong authentication instead.

2. **MAC Address Filtering?** No—MAC addresses are easily spoofed. Use 802.1X authentication.

3. **Wireless Intrusion Detection (WIDS):** Deploy wireless sensors to detect rogue access points, deauth attacks, and unauthorized clients.

4. **Regular Security Assessments:** Conduct annual wireless penetration tests to identify vulnerabilities.

5. **Physical Security:** Lock down access points to prevent tampering. Disable unused ports on APs.

### 4. Network Segmentation and VLANs

Network segmentation divides the network into smaller zones, limiting the blast radius of security incidents.

**Why Segment?**

Without segmentation, an attacker who compromises a single workstation can move laterally to access servers, databases, and sensitive systems. Segmentation creates security boundaries that contain breaches.

**Common Segmentation Zones:**

**DMZ (Demilitarized Zone):**

Public-facing services (web servers, email gateways, VPN concentrators) sit between two firewalls. Compromise of DMZ systems doesn't grant access to internal network.

**User Network:**

Employee workstations, separated from servers. Further segmented by department or sensitivity (finance, HR, general users).

**Server Network:**

Application servers, file servers, domain controllers. Further segmented by function (web tier, app tier, database tier).

**Management Network:**

Infrastructure management interfaces (server iLO/IPMI, network switch/router management, VMware vCenter). Access strictly limited to IT administrators.

**Guest Network:**

Internet-only access with no path to corporate resources.

**IoT/OT Network:**

Building automation, manufacturing equipment, security cameras. Isolated from IT network with unidirectional data flows where possible.

**Microsegmentation:**

Modern approach using software-defined networking to create granular security policies between individual workloads (especially in cloud/virtualized environments).

**VLAN Best Practices:**

- VLAN 1 should never be used (default VLAN with security weaknesses)

- Each security zone gets dedicated VLAN(s)

- Inter-VLAN routing only through firewall (not Layer 3 switches)

- Document VLAN assignments and IP ranges

- Use private IP addresses (10.x.x.x, 172.16-31.x.x, 192.168.x.x)

### 5. Intrusion Detection and Prevention Systems (IDS/IPS)

IDS/IPS monitors network traffic for malicious activity and known attack patterns.

**IDS vs. IPS:**

**Intrusion Detection System (IDS):**

Passive monitoring—alerts security team when suspicious activity detected but doesn't block traffic. Deployed as network tap or SPAN port mirror.

Advantages: No risk of blocking legitimate traffic, comprehensive logging

Disadvantages: Attacks succeed before response, requires 24/7 monitoring

**Intrusion Prevention System (IPS):**

Active inline deployment—blocks malicious traffic automatically. Deployed in-line between network segments.

Advantages: Immediate threat blocking, automatic response

Disadvantages: False positives can block legitimate traffic, requires careful tuning

**Most Modern Deployments:** IPS mode with careful tuning and bypass mechanisms for high availability.

**Detection Methods:**

**Signature-Based Detection:**

Match traffic against known attack patterns (SQL injection strings, malware signatures, exploit code). Fast and accurate for known threats but misses zero-day attacks.

**Anomaly-Based Detection:**

Establish baseline of normal network behavior, alert on deviations. Can detect unknown threats but generates more false positives.

**Behavioral Analysis:**

Machine learning models identify suspicious patterns (data exfiltration, command-and-control traffic, lateral movement).

**IDS/IPS Deployment Locations:**

- **Perimeter:** Between internet router and internal network (catch inbound attacks)

- **Internal Segments:** Between critical network zones (detect lateral movement)

- **Data Center:** Protect servers and databases (detect server compromises)

- **Cloud:** Virtual IPS in cloud environments (AWS Network Firewall, Azure Firewall)

**Tuning and Maintenance:**

IPS effectiveness depends on ongoing tuning:

- Start in IDS (alert-only) mode, monitor for false positives

- Gradually enable blocking for high-confidence signatures

- Update signatures weekly or daily for active threats

- Review alerts weekly to identify new attack patterns

- Adjust thresholds to reduce false positives

- Document tuning decisions and suppressions

### 6. Network Access Control (NAC)

NAC validates devices before allowing network access, ensuring endpoints meet security requirements.

**NAC Functions:**

**Device Authentication:**

Verify device identity before granting network access (certificate-based, 802.1X, MAC authentication).

**Posture Assessment:**

Check endpoint security status:

- Antivirus installed and updated?

- Operating system patches current?

- Disk encryption enabled?

- Firewall active?

- Required software installed?

**Dynamic Access Control:**

Grant different network access based on device compliance:

- Compliant corporate devices → full network access

- Non-compliant devices → quarantine VLAN with remediation access

- Guest devices → internet-only access

- Unknown devices → denied

**Common NAC Solutions:**

- Cisco Identity Services Engine (ISE)

- Aruba ClearPass

- ForeScout CounterACT

- Microsoft Network Access Protection (NAP)

- PacketFence (open source)

**NAC Deployment Considerations:**

**Phased Rollout:**

1. Deploy in monitor mode (log compliance but allow all access)

2. Enable enforcement for new devices

3. Gradually enforce for existing devices by department

4. Full enforcement after 3-6 months

**Exceptions and Challenges:**

- IoT devices that can't install agents (cameras, printers, building automation)

- Legacy systems that don't support 802.1X

- BYOD devices with limited control

- Visitor/contractor access requirements

## Network Security Monitoring and Logging

**What to Log:**

**Firewall Logs:**

- Denied traffic (detect attack attempts)

- Allowed traffic to sensitive resources

- Rule changes (audit trail)

- VPN connections (user access tracking)

**IDS/IPS Alerts:**

- All security events (attacks detected/blocked)

- Signature updates and tuning changes

- System health and performance

**DNS Queries:**

- Detect malware command-and-control domains

- Identify data exfiltration via DNS tunneling

- Track suspicious domain lookups

**Network Flow Data (NetFlow/sFlow):**

- Source/destination IP and port pairs

- Traffic volume and duration

- Protocol information

- Detect unusual traffic patterns

**SIEM Integration:**

Forward network logs to Security Information and Event Management (SIEM) platform for:

- Correlation with endpoint and application logs

- Alert aggregation and prioritization

- Incident investigation and forensics

- Compliance reporting

- Long-term retention

Common SIEM Solutions: Splunk, IBM QRadar, Microsoft Sentinel, Elastic Security, LogRhythm

**Log Retention Requirements:**

- **Security Logs:** 1 year minimum, 7 years for regulated industries

- **Firewall Logs:** 90 days minimum for troubleshooting, 1 year for security

- **IDS/IPS Alerts:** 1 year minimum

- **NetFlow Data:** 30-90 days (volume considerations)

## Compliance and Regulatory Requirements

### NIST Cybersecurity Framework

**Identify:**

- Asset inventory (all network devices and connections)

- Data flow mapping (where sensitive data travels)

- Risk assessment (network vulnerabilities)

**Protect:**

- Access controls (firewall rules, NAC, VPN)

- Network segmentation (isolate sensitive systems)

- Encryption (VPN, wireless, data in transit)

**Detect:**

- IDS/IPS deployment

- Network traffic monitoring

- Anomaly detection

**Respond:**

- Incident response procedures

- Network isolation capabilities

- Forensic data collection

**Recover:**

- Network restoration procedures

- Backup connectivity options

- Lessons learned process

### PCI-DSS (Payment Card Industry)

**Key Network Security Requirements:**

- **Requirement 1:** Install and maintain firewall configuration

- Document firewall rules

- Review rules every 6 months

- Restrict inbound/outbound traffic to necessary minimum

- **Requirement 2:** Change vendor-supplied defaults

- Change default passwords on network devices

- Disable unnecessary services

- Remove default accounts

- **Requirement 4:** Encrypt transmission of cardholder data

- TLS 1.2 or higher for internet transmission

- Strong cryptography and security protocols

- **Requirement 11:** Regularly test security systems

- Quarterly vulnerability scans

- Annual penetration testing

- IDS/IPS testing

### HIPAA (Healthcare)

**Technical Safeguards (§164.312):**

- **Access Control:** Unique user identification, automatic logoff, encryption

- **Audit Controls:** Log network access to ePHI

- **Integrity:** Protect ePHI from improper alteration

- **Transmission Security:** Encrypt ePHI in transit, implement VPN

### ISO 27001

**Relevant Controls:**

- **A.13.1 Network Security Management:** Network controls, security of network services, segregation of networks

- **A.13.2 Information Transfer:** Policies and procedures, agreements, electronic messaging, confidentiality agreements

## Implementation Guide: Phased Approach

### Phase 1: Foundation (Months 1-2)

**Activities:**

1. **Network Discovery and Documentation**

- Map all network devices and connections

- Document current firewall rules

- Identify network segments and VLANs

- List all remote access methods (VPNs, RDP, etc.)

2. **Security Assessment**

- Conduct vulnerability scan of network infrastructure

- Review firewall rule effectiveness

- Test wireless security

- Identify security gaps

3. **Policy Documentation**

- Document network security standards

- Create firewall rule request process

- Establish VPN access procedures

- Define wireless security requirements

**Deliverables:**

- Network diagram with security zones

- Current-state security assessment

- Network security policy document

- Quick wins list (easily fixed vulnerabilities)

### Phase 2: Quick Wins (Month 2-3)

**Activities:**

1. **Firewall Optimization**

- Remove unused firewall rules (20-40% typically)

- Fix overly permissive rules (any/any rules)

- Enable logging for critical rules

- Document all rules

2. **Wireless Security Hardening**

- Upgrade to WPA3 where possible

- Implement 802.1X authentication

- Separate guest and corporate wireless

- Deploy wireless intrusion detection

3. **VPN Security**

- Enforce multi-factor authentication

- Implement endpoint compliance checks

- Review and tighten VPN access rules

- Enable session logging

**Deliverables:**

- Cleaned firewall ruleset

- WPA3/802.1X wireless deployment

- MFA-protected VPN access

- 30-50% risk reduction

### Phase 3: Network Segmentation (Months 3-5)

**Activities:**

1. **Design Segmentation Strategy**

- Identify security zones (user, server, DMZ, guest, management)

- Define inter-zone access requirements

- Create VLAN and IP addressing plan

- Design firewall topology

2. **Implement Segmentation**

- Create VLANs for each zone

- Deploy inter-zone firewalling

- Migrate systems to appropriate zones

- Configure access control lists

3. **Test and Validate**

- Verify zone isolation

- Test required traffic flows

- Validate firewall rules

- Conduct penetration test

**Deliverables:**

- Segmented network architecture

- Documented zone boundaries

- Tested access controls

- Reduced blast radius of potential breaches

### Phase 4: Advanced Security (Months 5-8)

**Activities:**

1. **IDS/IPS Deployment**

- Select and deploy IPS solution

- Configure signature updates

- Tune for environment (reduce false positives)

- Enable blocking for high-confidence threats

2. **Network Access Control**

- Deploy NAC solution

- Define compliance policies

- Configure remediation workflows

- Phased enforcement rollout

3. **Enhanced Monitoring**

- Deploy SIEM platform

- Configure log forwarding

- Create correlation rules

- Establish SOC procedures

**Deliverables:**

- Operational IPS with tuned policies

- NAC enforcing endpoint compliance

- SIEM aggregating network security logs

- 24/7 security monitoring capability

### Phase 5: Continuous Improvement (Ongoing)

**Activities:**

- **Quarterly:** Firewall rule review and cleanup

- **Quarterly:** Vulnerability scanning of network infrastructure

- **Semi-Annual:** Wireless security assessment

- **Annual:** Network penetration testing

- **Annual:** Policy review and update

- **Continuous:** Threat intelligence integration, signature updates, log review

## Common Network Security Mistakes to Avoid

**1. Over-Reliance on Perimeter Security**

Modern threats include insider attacks, compromised credentials, and supply chain compromises. Defense-in-depth with internal segmentation is essential.

**2. Flat Network Architecture**

If everything is on one network, a single compromised device grants access to everything. Segment by security zone and sensitivity.

**3. Neglecting Wireless Security**

Treating wireless as "just another port" ignores unique wireless risks. Implement enterprise authentication and separate SSIDs.

**4. Poor Firewall Rule Hygiene**

Undocumented, unused, and overly permissive rules accumulate over time. Regular audits and cleanup are essential.

**5. Ignoring Encrypted Traffic**

80%+ of web traffic is HTTPS. Deploy SSL inspection (with privacy considerations) or use cloud security services.

**6. Insufficient Logging**

Can't investigate what you didn't log. Implement comprehensive logging with adequate retention.

**7. Lack of Network Visibility**

You can't protect what you can't see. Maintain accurate network documentation and use monitoring tools.

**8. Weak VPN Security**

Password-only VPN access is frequently compromised. Enforce MFA and endpoint compliance checks.

**9. Default Credentials**

Network devices shipped with default passwords are frequently compromised. Change all defaults immediately.

**10. No Incident Response Plan**

When a network breach occurs, time is critical. Pre-plan response procedures, isolation capabilities, and communication processes.

## Network Security Tools and Technologies

**Firewall Vendors:**

- **Enterprise:** Palo Alto Networks, Fortinet FortiGate, Cisco Firepower, Check Point

- **Cloud-Native:** AWS Network Firewall, Azure Firewall, Google Cloud Armor

- **Open Source:** pfSense, OPNsense (small deployments)

**IDS/IPS Solutions:**

- **Commercial:** Cisco Firepower, Palo Alto Threat Prevention, Fortinet FortiGate

- **Open Source:** Suricata, Snort (requires expertise to deploy/maintain)

**VPN Solutions:**

- **Traditional:** Cisco AnyConnect, Palo Alto GlobalProtect, Fortinet FortiClient

- **Zero Trust:** Zscaler Private Access, Cloudflare Access, Palo Alto Prisma Access

**Network Access Control:**

- Cisco Identity Services Engine (ISE)

- Aruba ClearPass

- ForeScout CounterACT

- PacketFence (open source)

**SIEM Platforms:**

- Splunk Enterprise Security

- IBM QRadar

- Microsoft Sentinel (cloud-native)

- Elastic Security

- LogRhythm

## Getting Started with the Template

The Network Security Policy Template provides a comprehensive framework ready for immediate deployment:

**What's Included:**

1. **Network Security Policy Document** (20+ pages)

- Scope and applicability

- Roles and responsibilities

- Security requirements for each network component

- Compliance mappings (NIST, ISO 27001, PCI-DSS, HIPAA)

2. **Firewall Rule Request Form**

- Business justification

- Source/destination requirements

- Approval workflow

- Review schedule

3. **VPN Access Request Form**

- User information and business need

- Access requirements

- MFA enrollment

- Acceptable use acknowledgment

4. **Wireless Security Standard**

- SSID configuration requirements

- Encryption standards

- Authentication methods

- Guest access procedures

5. **Network Segmentation Plan Template**

- Security zone definitions

- VLAN assignments

- Inter-zone access matrix

- Implementation roadmap

6. **Network Device Hardening Checklist**

- Configuration standards for routers, switches, firewalls

- Baseline security settings

- Audit procedures

7. **Network Security Monitoring Plan**

- What to log and where

- Alert thresholds

- Incident response triggers

- Reporting requirements

**How to Implement:**

1. **Download and Review** the template documents

2. **Customize** for your organization's environment and requirements

3. **Gain Executive Approval** for policy and implementation roadmap

4. **Conduct Current-State Assessment** using included checklists

5. **Prioritize** security gaps identified in assessment

6. **Implement** using phased approach (foundation → quick wins → segmentation → advanced)

7. **Document** all configurations and decisions

8. **Train** IT staff and users on new policies and procedures

9. **Monitor** compliance and effectiveness

10. **Review and Update** quarterly based on threat landscape changes

Whether you're establishing network security for the first time or enhancing an existing program, this template provides the structure, documentation, and best practices to protect your organization's network infrastructure.

Network security isn't a one-time project—it's an ongoing program of assessment, improvement, and adaptation to evolving threats. Start with the fundamentals, build incrementally, and maintain continuous improvement.

Your network is the backbone of your business operations. Protect it with a comprehensive, well-documented network security program.