Effectively block adult websites on iPhone and Mac: a technical guide

Reclaiming control over your attention sometimes requires technical barriers. Blocking adult websites on your Mac and iPhone seems simple in theory: there are dozens of paid apps that promise total blocking. In practice, most can be bypassed in minutes (VPN, private browsing, DoH, DNS change, uninstall). This guide presents a multi-layered, free, hard-to-bypass stack, built only on native Apple tools and open-source projects. Plan one hour of setup for both devices.

Why a single tool isn't enough

Effective blocking relies on multiple independent lines of defense. Block only at the browser level? Just install Brave or Firefox. Filter your home Wi-Fi DNS? Just switch to 4G. Install a blocker app? Just uninstall it. The rule is simple: each layer must hold on its own even if another falls.

The model below combines five layers on Mac and three on iPhone. All use documented Apple features or maintained open-source projects.

Mac: the full stack

Layer 1 — /etc/hosts file with community blocklist

The /etc/hosts file is the first place macOS checks to resolve a domain name, before any DNS server. Adding entries pointing to 0.0.0.0 makes the domain unreachable at the system level, regardless of browser, application, or configured DNS server.

The open-source project StevenBlack/hosts on GitHub maintains a consolidated list of over 150,000 adult domains, updated daily. To apply it:

sudo cp /etc/hosts /etc/hosts.backup
curl -sL https://raw.githubusercontent.com/StevenBlack/hosts/master/alternates/porn/hosts \
  | sudo tee -a /etc/hosts > /dev/null
sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder

Test: curl pornhub.com should fail instantly. If the command returns an HTTP code, the DNS cache isn't flushed — rerun the flush commands.

Layer 2 — Immutable lock on /etc/hosts

Without further protection, any user with sudo access can edit the file. The system flag schg (system immutable) prevents any modification, even by root, unless you boot into Recovery mode and disable SIP (System Integrity Protection).

sudo chflags schg /etc/hosts

To verify: ls -lO /etc/hosts should display the schg flag. To edit the file later, you'll first need to remove the lock with sudo chflags noschg /etc/hosts.

Layer 3 — Cover IPv6

Little-known trap: /etc/hosts with 0.0.0.0 only blocks IPv4. If a site also responds over IPv6 (most large sites do via Cloudflare), it remains reachable. The fix is to add mirror entries with the IPv6 null address :::

sudo chflags noschg /etc/hosts
grep '^0\.0\.0\.0' /etc/hosts | awk '{print ":: " $2}' | sudo tee -a /etc/hosts > /dev/null
sudo chflags schg /etc/hosts

Layer 4 — Apple Screen Time and iCloud Private Relay

Apple natively includes an adult content filter in Screen Time. Although basic, it adds an extra layer on Safari and all WebKit apps. Configuration: System Settings → Screen Time → Content & Privacy → Content Restrictions → Web Content → Limit Adult Websites. Then lock Screen Time with a passcode different from your login one.

Critical and often forgotten: iCloud Private Relay, included with iCloud+, routes Safari traffic through two Apple proxies and encrypts DNS queries. This is exactly the kind of feature that bypasses /etc/hosts. To disable: System Settings → Apple Account → iCloud → Private Relay → off.

Layer 5 — Cold Turkey Blocker as application layer

Cold Turkey Blocker (free version) adds three protections /etc/hosts doesn't cover: URL keyword filtering, application blocking, and most importantly the Frozen Turkey mode that makes the app impossible to uninstall during an active block. Install:

brew install --cask cold-turkey-blocker

Configuration: create a block named "Adult", add the predefined Adult Sites category, schedule 24/7 blocking, then enable Frozen Turkey in settings. The browser extension must be installed on Chrome, Brave and Firefox to activate keyword filtering.

Layer 6 — Disable DNS over HTTPS in browsers

Modern browsers (Chrome, Firefox, Brave) can enable DNS over HTTPS (DoH) internally, which fully bypasses /etc/hosts and the system DNS. Check in each:

• Chrome: chrome://settings/security → Use secure DNS → off
• Brave: brave://settings/security → Use secure DNS → off
• Firefox: about:preferences#privacy → DNS over HTTPS → Off
• Safari: no action needed, uses system DNS

iPhone: the full stack

iOS doesn't give access to /etc/hosts. The strategy relies on a Configuration Profile that forces all DNS queries through a filtering resolver, plus Screen Time to lock changes.

Layer 1 — DoH Configuration Profile with Cloudflare 1.1.1.3

Cloudflare offers 1.1.1.3 for free, a DNS resolver that automatically blocks adult content and malware. Unlike a regular DNS change in Wi-Fi settings, a DoH Configuration Profile applies system-wide, on cellular as on Wi-Fi, and encrypts queries so no intermediary can tamper with them.

The minimal profile contains a com.apple.dnsSettings.managed payload pointing to https://family.cloudflare-dns.com/dns-query. You can download it directly from the official site one.one.one.one/family/, or generate a custom one with Apple Configurator 2 (free on the Mac App Store).

Install: send the .mobileconfig file to the iPhone via AirDrop or email, then Settings → Profile Downloaded → Install. Verify: Settings → General → VPN, DNS & Device Management.

Layer 2 — Screen Time with locking passcode

Without a Screen Time lock, the profile is removable in three taps. This is the step that turns a cosmetic block into a real barrier.

1. Settings → Screen Time → Use Screen Time Passcode (different from your unlock code, ideally not memorized by yourself)
2. Content & Privacy Restrictions → on
3. Content Restrictions → Web Content → Limit Adult Websites
4. Account Changes → Don't Allow (prevents profile removal)
5. VPN → Don't Allow Changes (prevents installing a bypass VPN)
6. Mobile Data → Don't Allow Changes
7. Passcode Changes → Don't Allow

Layer 3 — Manual blacklist in Screen Time

The Cloudflare filter covers 99% of sites but may let some new domains through. To add them manually: Settings → Screen Time → Content Restrictions → Web Content → Limit Adult Websites → Never Allow → Add Website.

Limits you should know

No blocking system is foolproof. The following bypasses remain possible, in order of increasing difficulty:

• Full-tunnel system VPN (WireGuard, Tailscale) on Mac: can route DNS traffic through the tunnel and bypass /etc/hosts. On iPhone, the Don't Allow VPN Changes option in Screen Time blocks installing new VPNs.
• Boot into Recovery + disable SIP on Mac: lets you remove the schg lock and edit hosts. Requires knowing the admin password and physical access.
• Full DFU restore on iPhone: wipes everything, profile included. Requires being ready to lose all data.
• Apple Configurator 2 supervision mode: for absolute lock, you can supervise your own iPhone via Apple Configurator 2 on Mac, making the DoH profile non-removable except via full wipe. Cost: a complete iPhone reset at setup.

Maintenance and automation

The StevenBlack blocklist is updated daily with new domains. A monthly refresh script is enough to stay current:

#!/bin/bash
sudo chflags noschg /etc/hosts
sudo sed -i '' '/# === PORN BLOCKER START ===/,/# === PORN BLOCKER END ===/d' /etc/hosts
TMP=$(mktemp)
curl -sL https://raw.githubusercontent.com/StevenBlack/hosts/master/alternates/porn/hosts -o "$TMP"
echo "# === PORN BLOCKER START ===" | sudo tee -a /etc/hosts > /dev/null
grep '^0\.0\.0\.0' "$TMP" | sudo tee -a /etc/hosts > /dev/null
grep '^0\.0\.0\.0' "$TMP" | awk '{print ":: " $2}' | sudo tee -a /etc/hosts > /dev/null
echo "# === PORN BLOCKER END ===" | sudo tee -a /etc/hosts > /dev/null
sudo chflags schg /etc/hosts
sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder

Schedule it as a monthly cron job, or simply run it manually at regular intervals.

Conclusion

Solid blocking relies on stacking independent layers, not on a single miracle tool. The stack presented holds against 99% of everyday bypass attempts, at zero cost and roughly an hour of setup. To go further, signing a macOS Configuration Profile with an Apple Developer account allows locking the system DNS too and disabling Recovery mode. But at that point, you're entering commercial-product territory — for personal use, the stack above is more than enough.