DNS Monitoring: Changes, TTL, DNSSEC — Turnkey Setup

Imagine your site works, the server responds, but visitors see nothing. The cause: a DNS A record was changed an hour ago, and you only learned about it from user complaints. DNS monitoring is what separates control from flying blind. According to statistics, 60% of companies experience at least one DNS attack per year, and the average detection time without monitoring exceeds 6 hours. We've seen cases where clients lost traffic for hours due to a registrar account breach and record tampering. Our experience shows: without dedicated DNS monitoring, you're blind to one of the most vulnerable parts of your infrastructure.

Why Standard Server Monitoring Doesn't Protect Against DNS Attacks

When a site goes down, the usual first steps are checking server load, application logs, and databases. But the fault might be in DNS: an unauthorized A-record change, a broken DNSSEC signature, or a sudden TTL drop can make your site unavailable to thousands of users while the server itself is healthy. We've handled a case where a client's domain was unreachable for 6 hours due to a missed renewal — losses were tens of thousands of dollars. Since then, we've made domain expiration checks a mandatory component.

Risks of Not Monitoring DNS

• A/AAAA changes: Site shows third-party content or a blank page.
• MX hijacking: Email flows are redirected to an attacker's server, compromising correspondence and passwords.
• NS attacks: Full domain control lost — traffic diverted to phishing pages.
• TTL manipulation: Abnormally low TTL (<60 s) often precedes an attack.
• Broken DNSSEC: 30% of users (browsers with validation) cannot reach your site.
• Domain expiration: Expired domain loses all DNS configuration.

DNS Records to Monitor

Additionally, we monitor:

• TTL: Automatic alert when TTL drops below 300 seconds.
• DNSSEC: Validate RRSIG presence and correctness. Per RFC 4033, DNSSEC authenticates DNS responses.
• Domain expiration: Daily check, alert at 30 days before expiry.

How We Set Up DNS Monitoring Turnkey

We use a combination of lightweight Python scripts for quick starts and Prometheus Blackbox Exporter for industrial scale.

1. Audit current configuration — collect baseline records, verify DNSSEC, TTL, expiration date. Save baseline in a JSON snapshot.
2. Deploy Python change monitoring script — query three public resolvers (Google, Cloudflare, OpenDNS) and compare responses to baseline. Alert via Telegram, Slack, or PagerDuty within one minute. Average detection time: 60 seconds.
3. Integrate with Prometheus via Blackbox Exporter — create a dns_check module for each domain, verifying expected IP. Metrics flow into Grafana; alerts trigger if probe_success == 0 for 2m.
4. DNSSEC validation — periodically resolve with the DO (DNSSEC OK) flag and check for RRSIG. Critical alert on validation error.
5. WHOIS monitoring — daily check of days until domain expiration. Threshold: 30 days.

import dns.resolver
from dns.exception import DNSException

def check_dns(domain, expected_ip):
    try:
        answers = dns.resolver.resolve(domain, 'A')
        for rdata in answers:
            if rdata.address != expected_ip:
                alert(f"DNS change detected for {domain}")
    except (DNSException, IndexError) as e:
        alert(f"DNS error for {domain}: {e}")

Method comparison: Blackbox Exporter is preferable for 50+ domains — it provides ready metrics, Grafana integration, and scales without extra code. Python is convenient for rapid prototyping or custom checks (e.g., comparing records across resolvers).

What's Included

• Prepare and agree on list of monitored domains and records.
• Develop and deploy monitoring scripts (Python) or configure Blackbox Exporter.
• Set up alerts (Telegram, Slack, email, PagerDuty) with severity levels.
• Validate DNSSEC and WHOIS information.
• Document incident recovery procedures.
• 7-day test period with alert tuning.
• Handover and training for your team.

Timeline

Exact timeline depends on the number of domains and infrastructure complexity. Contact us to discuss monitoring for your domains — we'll analyze your configuration and propose an optimal solution.

Tools for Self-Check

• dig +dnssec example.com — manual DNSSEC verification.
• DNSCheck.tools — online check of all records.
• GitHub: dns-monitor — ready template for persistent monitoring (open-source).

For ongoing automated monitoring, scripts or Prometheus are essential. We share our code under open license.

Our Experience & Guarantees

Our engineers have 10+ years working with DNS infrastructure for high-load projects (up to 5000 RPS). We are certified in Prometheus, Python, BIND, and PowerDNS. We guarantee that the monitoring system will catch every change — if not, we'll reconfigure it for free.

DNS monitoring is an investment that pays off at the first incident. Order an audit today — get a consultation from our engineer and a timeline proposal.

Web Application Security: HTTPS, CSP, XSS, CSRF, WAF, DDoS Protection

A website breach rarely looks like in movies. More often it's: a bot finds an unprotected /admin/export endpoint, downloads the customer database, and closes the connection. Or: through an outdated WordPress plugin, a web shell is uploaded, and the server starts sending spam. Or quieter: an XSS in a comment field allows stealing admin session cookies, unnoticed for months. We have analyzed dozens of such cases — each vulnerability could have been fixed at the development or audit stage.

Web application security is not a single setting. It's layers of protection, each closing a separate class of attacks. Order an audit — we'll assess the project and deliver a turnkey plan within 2–4 weeks.

How do we ensure comprehensive web application security?

HTTPS and Proper TLS Configuration

HTTPS is the minimum mandatory level. But having an SSL certificate and having a properly configured TLS are different things.

In Nginx/Apache configuration we check:

• Protocols: only TLS 1.2 and TLS 1.3, SSLv3 and TLS 1.0/1.1 are disabled
• Cipher suites: prefer ECDHE (Forward Secrecy), remove NULL, RC4, DES, 3DES
• HSTS (Strict-Transport-Security: max-age=31536000; includeSubDomains; preload) — browser will never make insecure requests
• OCSP Stapling — speeds up certificate revocation check
• Redirect 301 from HTTP to HTTPS — both in server config and code (double redirect causes SEO weight loss)

Check: SSL Labs (ssllabs.com/ssltest) should show A or A+. If B, the configuration is weak.

Let's Encrypt + Certbot for production is standard. Automatic renewal via certbot renew in cron. Wildcard certificates for subdomains via DNS-01 challenge.

Content Security Policy: The Most Powerful and Complex Protection

CSP is an HTTP header that tells the browser which sources are allowed to load resources. A properly configured CSP completely blocks most XSS attacks, even if the vulnerability exists in the code.

The problem: breaking the site with an incorrect CSP is easy. default-src 'none' — and fonts, images, JS stop working. So we start with Content-Security-Policy-Report-Only — CSP logs violations but does not block anything. We monitor reports for 2–4 weeks, refine the policy, then switch to enforcement mode.

Example of a real policy for a site with Google Analytics, Google Fonts, and Stripe:

Content-Security-Policy:
  default-src 'self';
  script-src 'self' https://www.googletagmanager.com https://js.stripe.com 'nonce-{random}';
  style-src 'self' https://fonts.googleapis.com 'unsafe-inline';
  font-src 'self' https://fonts.gstatic.com;
  frame-src https://js.stripe.com;
  img-src 'self' data: https://www.google-analytics.com;
  connect-src 'self' https://api.stripe.com https://www.google-analytics.com;
  report-uri /csp-report;

nonce — a random string generated server-side per request. Inline scripts with the correct nonce are allowed; without nonce, they are blocked. This completely breaks XSS via <script>alert(1)</script>.

'unsafe-inline' in style-src is a compromise for inline styles. It's better to remove it by moving all styles to CSS files, but that requires refactoring.

Why XSS Remains the Most Common Vulnerability?

XSS (Cross-Site Scripting) — injection of JS code through user input. According to OWASP, XSS is in the top 3 web application vulnerabilities. Three types:

Protection: never insert user input into HTML without escaping. In PHP — htmlspecialchars() with ENT_QUOTES. In Laravel Blade templates — {{ $var }} is safe, {!! $var !!} is dangerous. In React — {variable} is safe, dangerouslySetInnerHTML is dangerous. For Rich Text — use htmlpurifier on PHP or DOMPurify in the browser.

CSRF: Protecting Forms and APIs

CSRF (Cross-Site Request Forgery) — an attacker forces the victim's browser to send a request on their behalf. Example: a user is logged into a bank, opens a malicious page, which makes fetch('https://bank.ru/transfer?to=evil&amount=50000') — if the bank is unprotected, money is transferred.

CSRF tokens — standard protection for forms: the server generates a random token, stores it in the session, and inserts it as a hidden field in the form. On POST request, the token is verified. The attacker does not know the token. Laravel does this automatically with @csrf.

SameSite cookies — modern protection: SameSite=Strict or SameSite=Lax prevents the browser from sending cookies in cross-site requests. Works in all modern browsers.

API without sessions (JWT, Bearer tokens) — CSRF is irrelevant if the token is not stored in a cookie (but in the Authorization header or localStorage). However, localStorage is vulnerable to XSS — so for sensitive data, HttpOnly cookies with SameSite are preferable.

WAF and DDoS Protection

WAF (Web Application Firewall) filters HTTP traffic for attacks: SQL injection, XSS, path traversal, known exploit patterns. Options:

• Cloudflare WAF — cloud-based, OWASP Top 10 rules out of the box, custom rules via expressions. Managed Rules automatically block new threats.
• ModSecurity (Nginx/Apache) — self-hosted, OWASP Core Rule Set (CRS). Flexible but requires tuning and monitoring of false positives.
• AWS WAF — for infrastructure on AWS, integrates with CloudFront and ALB.

DDoS protection. Cloudflare at L3/L4/L7 is the de facto standard for most sites. Automatic mitigation of volumetric attacks, Under Attack Mode during active attacks. For critical infrastructure — Cloudflare Magic Transit or specialized solutions (Qrator, StormWall for the Russian market).

Rate Limiting at the application level — an additional layer. Laravel ThrottleRequests middleware: 60 requests per minute per IP for general endpoints, 5 for /login and /password/reset. Redis as a counter store — mandatory for horizontally scalable systems (otherwise limits are not synchronized between servers).

Other Mandatory Measures

Security headers. Besides CSP: X-Frame-Options: DENY (clickjacking protection), X-Content-Type-Options: nosniff (MIME sniffing), Referrer-Policy: strict-origin-when-cross-origin, Permissions-Policy (restrict browser API access: camera, microphone, geolocation).

SQL injection. Prepared statements everywhere. No concatenation of user input into SQL strings. ORM (Eloquent, Doctrine) protects by default. $wpdb->prepare() in WordPress is mandatory.

Dependency updates. composer audit and npm audit in CI/CD pipeline. Dependabot or Renovate for automatic PRs with updates. Critical CVEs — patch within 24 hours.

Secrets and configuration. .env — never in Git. Secrets in production — via CI/CD environment variables (GitHub Secrets, GitLab CI Variables) or HashiCorp Vault. Leak detection: git-secrets, truffleHog in pre-commit hooks.

How We Work

1. Audit — code scanning, configuration review, dependency analysis, manual business logic verification.
2. Planning — vulnerability remediation plan, stack selection (CSP, WAF, rate limiting).
3. Implementation — TLS setup, CSP configuration, headers, Rate Limiting, WAF.
4. Testing — re-penetration test, load testing, false positive check.
5. Deployment and Monitoring — enable production CSP, set up alerts, train the team.

What's Included

• Report with found vulnerabilities and recommendations (PDF + code snippets)
• Ready TLS configuration (Nginx/Apache)
• CSP policy with Report-Only and production versions
• WAF and Rate Limiting setup
• Dependency update plan
• Access to monitoring tools (Sentry, Datadog)
• 30 days of post-audit support (consultations, fixes)

Timeline and Cost

The budget is calculated individually — contact us for a project evaluation.