How to Use a URL Blocker to Protect Your Team and Kids

Build Your Own URL Blocker: Simple Steps for Network-Level Blocking

Overview

A network-level URL blocker stops requests to specific domains or URLs before they reach client devices—useful for parental controls, workplace filtering, or blocking ads/malware across your network. Common approaches: DNS filtering, gateway/proxy filtering, router firewall rules, and inline network appliances.

What you’ll need

• A network gateway device (router, dedicated PC, or Raspberry Pi).
• Control over DHCP/DNS or the ability to set a network DNS server.
• Basic networking knowledge (IP addresses, DNS, routing).
• Optional: proxy server software (e.g., Squid), firewall (iptables, pf), or DNS filtering software (Pi-hole, AdGuard Home).

Step-by-step (practical, prescriptive)

1. Choose your blocking method (default: DNS filtering)
   • DNS filtering is simple, device-agnostic, and low-overhead. Use Pi-hole or AdGuard Home on a Raspberry Pi or server.
2. Set up a DNS filter
   • Install Pi-hole or AdGuard Home on a device connected to your network.
   • Configure it as the network’s DNS server via your router’s DHCP settings so all clients use it automatically.
3. Populate blocklists
   • Import community-maintained blocklists (ads, trackers, malware).
   • Add custom domain/URL entries you want blocked. Note: DNS blocks by domain; blocking specific URL paths requires a proxy/firewall.
4. Enforce HTTPS-aware blocking (optional)
   • For domains served over HTTPS, DNS blocking still works for entire domains. To block specific HTTPS URLs or paths, deploy a transparent proxy with TLS interception (complex, privacy-sensitive) or use application-layer filtering on a gateway appliance.
5. Use a proxy for URL-path blocking
   • Install Squid or another proxy on your gateway and configure it as a transparent proxy.
   • Write ACLs to deny requests matching URL patterns (e.g., regex for paths).
   • Route HTTP/HTTPS traffic through the proxy; note HTTPS path blocking requires TLS interception or SNI-based filtering.
6. Harden and monitor
   • Prevent clients from bypassing the DNS filter by blocking external DNS (port 53) at the router/firewall so only your DNS is used.
   • Monitor logs for blocked requests and false positives; refine lists.
7. Maintain and update
   • Regularly update blocklists and software.
   • Review logs and whitelist false positives as needed.

Pros and cons

• Pros: Central control, device-agnostic (DNS), scalable, low cost (Pi).
• Cons: DNS-level blocks are domain-wide only; per-URL/path blocking needs proxies and may require TLS interception; more advanced setups can be complex and raise privacy/legal considerations.

Quick example: Pi-hole + router

• Install Pi-hole on Raspberry Pi.
• Set router DHCP to advertise Pi-hole IP as DNS server.
• Add domain blocks in Pi-hole admin UI.
• Block outbound DNS (port 53) to force use of Pi-hole.