This document outlines security considerations and best practices for deploying and operating the Go Load Balancer.

The Go Load Balancer is designed with security in mind, providing several features to help secure your infrastructure:

• TLS termination
• IP-based access control
• Rate limiting
• Header validation and transformation
• Secure defaults

The load balancer supports TLS termination for secure client connections. Configure TLS in your configuration file:

server:
  address: ":443"
  tls_cert: "/path/to/cert.pem"
  tls_key: "/path/to/key.pem"

For optimal security, use the following TLS configuration:

tlsConfig := &tls.Config{
    MinVersion:               tls.VersionTLS12,
    CurvePreferences:         []tls.CurveID{tls.X25519, tls.CurveP256},
    PreferServerCipherSuites: true,
    CipherSuites: []uint16{
        tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
        tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
        tls.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
        tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
        tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
        tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
    },
}

Deploy the load balancer in a secure network architecture:

graph TD
    Internet[Internet] -->|HTTPS| FW[Firewall]
    FW -->|HTTPS| LB[Load Balancer]
    LB -->|HTTP| BE1[Backend 1]
    LB -->|HTTP| BE2[Backend 2]
    
    subgraph "Public Network"
        Internet
        FW
    end
    
    subgraph "DMZ"
        LB
    end
    
    subgraph "Private Network"
        BE1
        BE2
    end

Implement firewall rules to restrict access to the load balancer:

• Allow incoming connections only on necessary ports (e.g., 80, 443)
• Allow outgoing connections only to backend servers
• Block all other traffic

Example iptables rules:

# Allow incoming HTTP/HTTPS
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT

# Allow outgoing connections to backend servers
iptables -A OUTPUT -p tcp --dport 8080 -d 10.0.0.0/24 -j ACCEPT

# Allow established connections
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

# Drop all other traffic
iptables -A INPUT -j DROP
iptables -A OUTPUT -j DROP

The load balancer includes an IP-based access control system. Configure it in your routing rules:

routing_rules:
  - match:
      path: "/admin/*"
    target_pool: "admin-servers"
    policies:
      - acl: "allow:192.168.1.0/24,deny:0.0.0.0/0"

While the load balancer doesn't directly handle authentication, you can implement it using header-based routing and transformations:

routing_rules:
  - match:
      path: "/api/*"
      headers:
        Authorization: "Bearer .*"
    target_pool: "api-servers"
    policies:
      - transform: "add-header:X-Authenticated:true"
  
  - match:
      path: "/api/*"
    target_pool: "auth-servers"

Configure rate limiting to protect against DoS attacks:

routing_rules:
  - match:
      path: "/api/*"
    target_pool: "api-servers"
    policies:
      - rate_limit: "100/minute"

The rate limiter uses a token bucket algorithm and is keyed by client IP address.

Add security headers to responses:

routing_rules:
  - match:
      path: "/*"
    target_pool: "web-servers"
    policies:
      - transform: "add-header:Strict-Transport-Security:max-age=31536000; includeSubDomains,add-header:X-Content-Type-Options:nosniff,add-header:X-Frame-Options:DENY,add-header:Content-Security-Policy:default-src 'self'"

Validate and sanitize headers to prevent injection attacks:

func sanitizeHeaders(r *http.Request) {
    // Remove potentially dangerous headers
    r.Header.Del("X-Forwarded-Host")
    
    // Add safe headers
    r.Header.Set("X-Forwarded-For", getClientIP(r))
}

Run the load balancer as a non-root user:

FROM golang:1.24-alpine AS builder
# ... build steps ...

FROM alpine:3.16
RUN addgroup -S loadbalancer && adduser -S loadbalancer -G loadbalancer
USER loadbalancer
# ... rest of Dockerfile ...

Secure your container deployment:

FROM golang:1.24-alpine AS builder
# ... build steps ...

FROM alpine:3.16
# Add non-root user
RUN addgroup -S loadbalancer && adduser -S loadbalancer -G loadbalancer

# Install security updates
RUN apk update && apk upgrade

# Set permissions
COPY --from=builder --chown=loadbalancer:loadbalancer /go-lb /app/go-lb
COPY --from=builder --chown=loadbalancer:loadbalancer /configs /app/configs

# Set security options
USER loadbalancer
WORKDIR /app
EXPOSE 8080

# Use exec form for proper signal handling
ENTRYPOINT ["/app/go-lb"]
CMD ["--config", "/app/configs/config.yml"]

Run with security options:

docker run --security-opt=no-new-privileges --cap-drop=ALL --read-only go-loadbalancer:latest

When deploying to Kubernetes, use a security context:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: go-loadbalancer
spec:
  template:
    spec:
      securityContext:
        runAsUser: 1000
        runAsGroup: 1000
        fsGroup: 1000
        runAsNonRoot: true
      containers:
      - name: go-loadbalancer
        securityContext:
          allowPrivilegeEscalation: false
          capabilities:
            drop:
            - ALL
          readOnlyRootFilesystem: true

Enable security-related logging:

logging:
  level: "info"
  security_events: true

Log security events:

func logSecurityEvent(logger *logging.Logger, event string, r *http.Request) {
    logger.Info("Security event", 
        "event", event,
        "ip", getClientIP(r),
        "path", r.URL.Path,
        "method", r.Method,
        "user_agent", r.UserAgent(),
    )
}

Monitor for security events:

graph TD
    LB[Load Balancer] -->|Logs| LogCollector[Log Collector]
    LB -->|Metrics| Prometheus[Prometheus]
    
    LogCollector -->|Security Events| SIEM[Security Information and Event Management]
    Prometheus -->|Metrics| Grafana[Grafana]
    
    SIEM -->|Alerts| AlertManager[Alert Manager]
    Grafana -->|Dashboards| SecurityTeam[Security Team]
    AlertManager -->|Notifications| SecurityTeam

• Enable TLS with strong cipher suites
• Configure proper access control
• Implement rate limiting
• Add security headers
• Run as non-root user
• Use a read-only filesystem
• Drop unnecessary capabilities
• Enable security logging
• Set up security monitoring
• Regularly update dependencies
• Perform security scanning
• Implement network isolation
• Configure firewall rules

Regularly scan dependencies for vulnerabilities:

go list -m all | xargs go-vulncheck

Keep dependencies up to date:

go get -u all
go mod tidy

Scan the codebase for security issues:

gosec ./...

The following threat model outlines potential security threats and mitigations:

graph TD
    Client[Client] -->|HTTPS| LB[Load Balancer]
    
    subgraph "Security Controls"
        TLS[TLS Termination]
        ACL[Access Control]
        RL[Rate Limiting]
        HT[Header Transformation]
    end
    
    LB --> TLS
    TLS --> ACL
    ACL --> RL
    RL --> HT
    
    HT -->|HTTP| Backend[Backend Servers]

If you discover a security vulnerability, please follow these steps:

1. Do not disclose the vulnerability publicly
2. Email [email protected] with details of the vulnerability
3. Allow time for the vulnerability to be addressed before public disclosure

Security patches will be released as soon as possible after a vulnerability is discovered. Users should update to the latest version to receive security fixes.

• Ensure proper handling of personal data
• Implement data minimization
• Configure appropriate logging
• Consider data residency requirements

If handling payment card data:

• Implement strong access control
• Use TLS 1.2 or higher
• Enable comprehensive logging
• Segment networks
• Regularly test security systems