Cloudflare Skill

Complete guide for managing Cloudflare services - DNS, Tunnels, Zero Trust, and more.

Quick Reference

Cloudflare Services

Service	Purpose
DNS	Domain name resolution with proxy
CDN	Content delivery and caching
Tunnels	Expose local services securely
Zero Trust	Identity-based access control
WAF	Web application firewall
Workers	Serverless edge computing
Pages	Static site hosting

CLI Installation

# cloudflared (Tunnels)
# macOS
brew install cloudflared

# Linux
curl -L https://github.com/cloudflare/cloudflared/releases/latest/download/cloudflared-linux-amd64 -o cloudflared
chmod +x cloudflared
sudo mv cloudflared /usr/local/bin/

# Windows
winget install Cloudflare.cloudflared

# Wrangler (Workers/Pages)
npm install -g wrangler

---

1. DNS Management

Add DNS Records

# Via API
curl -X POST "https://api.cloudflare.com/client/v4/zones/{zone_id}/dns_records" \
  -H "Authorization: Bearer {api_token}" \
  -H "Content-Type: application/json" \
  --data '{
    "type": "A",
    "name": "www",
    "content": "192.0.2.1",
    "ttl": 1,
    "proxied": true
  }'

Common Record Types

# A Record (IPv4)
Type: A
Name: www
Content: 192.0.2.1
Proxied: Yes

# AAAA Record (IPv6)
Type: AAAA
Name: www
Content: 2001:db8::1
Proxied: Yes

# CNAME Record
Type: CNAME
Name: blog
Content: www.example.com
Proxied: Yes

# MX Record (Email)
Type: MX
Name: @
Content: mail.example.com
Priority: 10
Proxied: No  # MX cannot be proxied

# TXT Record
Type: TXT
Name: @
Content: "v=spf1 include:_spf.google.com ~all"

Proxy Status

# Orange Cloud (Proxied)
- Traffic goes through Cloudflare
- DDoS protection enabled
- CDN caching enabled
- SSL/TLS termination at edge
- Real IP hidden

# Grey Cloud (DNS Only)
- Direct connection to origin
- No Cloudflare protection
- Required for: MX, non-HTTP services

---

2. Cloudflare Tunnels

Create Tunnel

# Login to Cloudflare
cloudflared tunnel login

# Create tunnel
cloudflared tunnel create my-tunnel

# List tunnels
cloudflared tunnel list

# Delete tunnel
cloudflared tunnel delete my-tunnel

Configure Tunnel

# ~/.cloudflared/config.yml
tunnel: <tunnel-id>
credentials-file: /root/.cloudflared/<tunnel-id>.json

ingress:
  # Web application
  - hostname: app.example.com
    service: http://localhost:8080

  # Home Assistant
  - hostname: ha.example.com
    service: http://localhost:8123
    originRequest:
      noTLSVerify: true

  # SSH access
  - hostname: ssh.example.com
    service: ssh://localhost:22

  # Catch-all (required)
  - service: http_status:404

Run Tunnel

# Run manually
cloudflared tunnel run my-tunnel

# Run with config
cloudflared tunnel --config ~/.cloudflared/config.yml run my-tunnel

# Install as service
sudo cloudflared service install
sudo systemctl start cloudflared
sudo systemctl enable cloudflared

Docker Tunnel

services:
  cloudflared:
    image: cloudflare/cloudflared:latest
    container_name: cloudflared
    restart: unless-stopped
    command: tunnel --no-autoupdate run --token ${TUNNEL_TOKEN}
    environment:
      - TUNNEL_TOKEN=your-tunnel-token

Quick Tunnel (Temporary)

# Expose local service instantly (no config needed)
cloudflared tunnel --url http://localhost:3000

# Output: https://random-name.trycloudflare.com

---

3. Zero Trust / Access

Create Access Application

# Via Dashboard: Zero Trust > Access > Applications

# API example
curl -X POST "https://api.cloudflare.com/client/v4/accounts/{account_id}/access/apps" \
  -H "Authorization: Bearer {api_token}" \
  -H "Content-Type: application/json" \
  --data '{
    "name": "Internal App",
    "domain": "app.example.com",
    "type": "self_hosted",
    "session_duration": "24h"
  }'

Access Policies

# Email-based access
Policy Name: Allowed Users
Decision: Allow
Include:
  - Emails ending in: @company.com

# Group-based access
Policy Name: Admin Group
Decision: Allow
Include:
  - Access Groups: Administrators
Require:
  - Country: United States

# One-time PIN
Policy Name: Contractors
Decision: Allow
Include:
  - Emails: contractor@external.com
Authentication Method: One-time PIN

Service Tokens

# Create service token for API/automation access
# Zero Trust > Access > Service Auth > Service Tokens

# Use in requests
curl -H "CF-Access-Client-Id: {client_id}" \
     -H "CF-Access-Client-Secret: {client_secret}" \
     https://app.example.com/api

WARP Client

# Install WARP for device tunnel
# Connects device to Zero Trust network

# Enroll device
# Zero Trust > Settings > WARP Client > Device enrollment

# Device posture checks
- Require disk encryption
- Require firewall enabled
- Require specific OS version

---

4. WAF (Web Application Firewall)

Managed Rulesets

# Enable in Dashboard: Security > WAF > Managed rules

Rulesets:
  - Cloudflare Managed Ruleset (OWASP)
  - Cloudflare OWASP Core Ruleset
  - Exposed Credentials Check

Custom Rules

# Block specific countries
(ip.geoip.country in {"CN" "RU" "KP"})
Action: Block

# Rate limiting
(http.request.uri.path contains "/api/")
Rate: 100 requests per minute
Action: Challenge

# Block bad bots
(cf.client.bot and not cf.verified_bot_category in {"Search Engine Crawler"})
Action: Block

# Protect admin area
(http.request.uri.path contains "/admin" and not ip.src in {192.168.1.0/24})
Action: Block

Firewall Rules

# Allow only specific IPs
(not ip.src in {192.168.1.100 10.0.0.0/8})
Action: Block

# Challenge suspicious requests
(cf.threat_score gt 30)
Action: Managed Challenge

# Skip WAF for trusted paths
(http.request.uri.path eq "/health")
Action: Skip (all remaining rules)

---

5. Page Rules & Cache

Page Rules

# Force HTTPS
URL: http://*example.com/*
Setting: Always Use HTTPS

# Cache everything
URL: *example.com/static/*
Settings:
  - Cache Level: Cache Everything
  - Edge Cache TTL: 1 month

# Bypass cache for API
URL: *example.com/api/*
Settings:
  - Cache Level: Bypass

# Redirect
URL: old.example.com/*
Setting: Forwarding URL (301)
Destination: https://new.example.com/$1

Cache Settings

# Browser Cache TTL
Respect Existing Headers / Override with: 4 hours

# Edge Cache TTL
2 hours (default) to 1 month

# Cache by device type
Mobile, Desktop, Tablet variations

# Purge cache
curl -X POST "https://api.cloudflare.com/client/v4/zones/{zone_id}/purge_cache" \
  -H "Authorization: Bearer {api_token}" \
  -H "Content-Type: application/json" \
  --data '{"purge_everything":true}'

---

6. Workers

Create Worker

# Initialize project
wrangler init my-worker
cd my-worker

# Login
wrangler login

# Deploy
wrangler deploy

Basic Worker

// src/index.js
export default {
  async fetch(request, env, ctx) {
    const url = new URL(request.url);

    // Simple response
    if (url.pathname === "/") {
      return new Response("Hello from Cloudflare Workers!");
    }

    // Proxy request
    if (url.pathname.startsWith("/api/")) {
      const apiUrl = "https://api.backend.com" + url.pathname;
      return fetch(apiUrl, request);
    }

    return new Response("Not Found", { status: 404 });
  },
};

Worker with KV Storage

// wrangler.toml
// [[kv_namespaces]]
// binding = "MY_KV"
// id = "xxx"

export default {
  async fetch(request, env) {
    // Read from KV
    const value = await env.MY_KV.get("key");

    // Write to KV
    await env.MY_KV.put("key", "value");

    return new Response(value);
  },
};

wrangler.toml

name = "my-worker"
main = "src/index.js"
compatibility_date = "2024-01-01"

[vars]
API_KEY = "secret"

[[kv_namespaces]]
binding = "MY_KV"
id = "your-kv-namespace-id"

[[r2_buckets]]
binding = "MY_BUCKET"
bucket_name = "my-bucket"

---

7. Pages (Static Sites)

Deploy Static Site

# Connect to Git (Dashboard)
# Pages > Create a project > Connect to Git

# Direct upload
wrangler pages deploy ./dist

# Deploy with build
wrangler pages deploy ./dist --project-name my-site

Build Configuration

# Framework presets available:
- Next.js
- Nuxt
- SvelteKit
- Astro
- Hugo
- Jekyll
- Gatsby

# Custom build
Build command: npm run build
Build output directory: dist
Root directory: /

Environment Variables

# Via Dashboard or wrangler.toml
[env.production.vars]
API_URL = "https://api.example.com"

[env.preview.vars]
API_URL = "https://staging-api.example.com"

---

8. SSL/TLS

SSL Modes

Off: No encryption (not recommended)
Flexible: HTTPS to Cloudflare, HTTP to origin
Full: HTTPS end-to-end (self-signed OK)
Full (Strict): HTTPS end-to-end (valid cert required)

Origin Certificates

# Generate origin certificate
# SSL/TLS > Origin Server > Create Certificate

# Valid for up to 15 years
# Only trusted by Cloudflare (not browsers)
# Use for origin server to Cloudflare connection

Edge Certificates

# Automatic (free)
Universal SSL - covers *.example.com and example.com

# Advanced (paid)
- Custom hostnames
- Dedicated certificates
- Total TLS

---

9. API Usage

Authentication

# API Token (recommended)
curl -H "Authorization: Bearer {api_token}" \
  "https://api.cloudflare.com/client/v4/user/tokens/verify"

# API Key (legacy)
curl -H "X-Auth-Email: {email}" \
     -H "X-Auth-Key: {api_key}" \
  "https://api.cloudflare.com/client/v4/user"

Common API Calls

# List zones
curl -X GET "https://api.cloudflare.com/client/v4/zones" \
  -H "Authorization: Bearer {token}"

# Get zone details
curl -X GET "https://api.cloudflare.com/client/v4/zones/{zone_id}" \
  -H "Authorization: Bearer {token}"

# List DNS records
curl -X GET "https://api.cloudflare.com/client/v4/zones/{zone_id}/dns_records" \
  -H "Authorization: Bearer {token}"

# Update DNS record
curl -X PUT "https://api.cloudflare.com/client/v4/zones/{zone_id}/dns_records/{record_id}" \
  -H "Authorization: Bearer {token}" \
  -H "Content-Type: application/json" \
  --data '{"type":"A","name":"www","content":"192.0.2.2","ttl":1,"proxied":true}'

# Purge cache
curl -X POST "https://api.cloudflare.com/client/v4/zones/{zone_id}/purge_cache" \
  -H "Authorization: Bearer {token}" \
  -H "Content-Type: application/json" \
  --data '{"purge_everything":true}'

---

10. Troubleshooting

Common Issues

DNS not propagating:

# Check DNS propagation
dig +short example.com @1.1.1.1

# Verify Cloudflare nameservers
dig NS example.com

# Clear DNS cache
# Cloudflare Dashboard > DNS > clear cache

Tunnel not connecting:

# Check tunnel status
cloudflared tunnel info my-tunnel

# View logs
cloudflared tunnel --loglevel debug run my-tunnel

# Verify credentials
ls ~/.cloudflared/

# Re-authenticate
cloudflared tunnel login

SSL errors:

# Error 525: SSL handshake failed
- Ensure origin has valid SSL certificate
- Check SSL mode (try Full instead of Full Strict)

# Error 526: Invalid SSL certificate
- Origin certificate expired or invalid
- Use Cloudflare Origin Certificate

# Mixed content
- Ensure all resources use HTTPS
- Enable Automatic HTTPS Rewrites

5xx errors:

# Error 520: Web server returned unknown error
- Check origin server is running
- Verify origin responds on correct port

# Error 521: Web server is down
- Origin server not responding
- Check firewall allows Cloudflare IPs

# Error 522: Connection timed out
- Origin server overloaded
- Check origin firewall

# Error 524: A timeout occurred
- Origin took too long (>100s)
- Optimize origin response time

---

Best Practices

1. Use API tokens with minimal permissions (not global API key)
2. Enable 2FA on Cloudflare account
3. Use Full (Strict) SSL mode with valid origin certificates
4. Whitelist Cloudflare IPs at origin firewall
5. Enable Under Attack Mode during DDoS
6. Use Page Rules sparingly (3 free, use Transform Rules instead)
7. Monitor analytics for unusual traffic patterns
8. Keep tunnels updated with automatic updates or regular manual updates
9. Use Zero Trust for internal applications
10. Cache static assets aggressively at edge