Stop playing whack-a-mole with malicious or inappropriate domains; here is how I source master blocklists and implement automated egress filtering to keep your production environment clean.

Sourcing the Master Lists: Dealing with NSFW Traffic on Production Networks

I remember back in 2018, I was pulling an all-nighter on prod-nat-gateway-02 trying to figure out why our egress costs were spiking. I dug into the flow logs and found a “ghost in the machine”—a container in our dev cluster had been compromised and was essentially acting as a scraper for some high-traffic adult sites. I spent three hours hunting for a comprehensive list of domains to block just to get through the night. It’s an awkward conversation to have with a CTO at 3:00 AM, but it’s a reality of the job: if you don’t know where these links are, you can’t stop them from hitting your network.

The core problem isn’t usually a malicious employee; it’s “Shadow IT” or automated scripts that pull from unfiltered datasets. When you’re building a web crawler or a link preview service, if you don’t have a curated “denylist,” you’re eventually going to serve something that will get you a call from HR or, worse, a security auditor. We need these links not because we want to visit them, but because we need to build the “Great Wall” around our infrastructure.

The Fixes

1. The Quick Fix: The Community-Maintained Blocklist

If you need to stop the bleeding right now, you don’t build your own list. You use what the community has already perfected. For a quick-and-dirty fix on a single Linux jump box or a dev server, I usually pull from the StevenBlack or OISD repositories. These are the gold standard for Pi-hole users and DevOps engineers alike.

# A quick bash hack to update your hosts file with a master NSFW blocklist
curl -s https://raw.githubusercontent.com/StevenBlack/hosts/master/alternates/porn/hosts | sudo tee -a /etc/hosts > /dev/null
# Restart your networking service
sudo systemctl restart systemd-resolved

Pro Tip: This is a “hacky” solution. It works for a single VM, but do not try to manage 500 nodes this way. You will regret the configuration drift.

2. The Permanent Fix: DNS Sinkholing (The Cloud Architect Way)

At TechResolve, we don’t touch individual hosts. We handle this at the DNS level. By using a service like Cloudflare Gateway or AWS Route 53 Resolver DNS Firewall, you can toggle “Adult Content” categories with a single API call. This is how you protect the entire VPC without installing a single agent.

resource "aws_route53_resolver_firewall_rule_group" "nsfw_block" {
  name = "block-inappropriate-content"
}

resource "aws_route53_resolver_firewall_rule" "block_adult" {
  name                    = "BlockAdultDomains"
  action                  = "BLOCK"
  block_response          = "NXDOMAIN"
  firewall_domain_list_id = aws_route53_resolver_firewall_domain_list.managed_adult_list.id
  firewall_rule_group_id  = aws_route53_resolver_firewall_rule_group.nsfw_block.id
  priority                = 100
}

3. The ‘Nuclear’ Option: Strict Egress Whitelisting

If you’re running a high-security environment (like prod-db-01 which should never be talking to the outside world anyway), the “Nuclear Option” is to block *everything* by default. Instead of looking for links to block, you only allow links you trust. It’s a pain to maintain, but it’s the only way to be 100% sure.

Look, sourcing these links isn’t about the content—it’s about the metadata. As engineers, we treat these URLs like any other malicious indicator. Use the community lists, automate the deployment via Terraform, and for the love of all that is holy, check your egress logs on prod-edge-gateway before your security auditor does.

Darian Vance

Lead Cloud Architect & DevOps Strategist

With over 12 years in system architecture and automation, Darian specializes in simplifying complex cloud infrastructures. An advocate for open-source solutions, he founded TechResolve to provide engineers with actionable, battle-tested troubleshooting guides and robust software alternatives.

🤖 Frequently Asked Questions