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Attempt to block/redirect DNS queries to adguard.

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This commit is contained in:
Nolan Darilek 2025-07-21 21:47:51 -04:00
parent 573295a717
commit c838f1e6e5
1 changed files with 56 additions and 0 deletions
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56
hosts/router/default.nix
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@ -209,6 +209,58 @@
-j DSCP --set-dscp-class cs1 \
-m comment --comment "Bulk HTTPS downloads (>50MB)"
##############################################################################
# DNS INTERCEPTION - Force all DNS through AdGuard Home
##############################################################################
# Redirect standard DNS queries (port 53) to AdGuard
# Skip packets from the router itself to prevent loops
iptables -t nat -A PREROUTING -i lan -p udp --dport 53 ! -s 192.168.0.1 \
-j DNAT --to-destination 192.168.0.1:53 \
-m comment --comment "Redirect UDP DNS to AdGuard"
iptables -t nat -A PREROUTING -i lan -p tcp --dport 53 ! -s 192.168.0.1 \
-j DNAT --to-destination 192.168.0.1:53 \
-m comment --comment "Redirect TCP DNS to AdGuard"
# Block any DNS queries that try to bypass AdGuard
iptables -A FORWARD -i lan -p udp --dport 53 ! -d 192.168.0.1 \
-j REJECT --reject-with icmp-port-unreachable \
-m comment --comment "Block external UDP DNS"
iptables -A FORWARD -i lan -p tcp --dport 53 ! -d 192.168.0.1 \
-j REJECT --reject-with tcp-reset \
-m comment --comment "Block external TCP DNS"
# Block DNS over TLS (DoT) on port 853
iptables -A FORWARD -i lan -p tcp --dport 853 \
-j REJECT --reject-with tcp-reset \
-m comment --comment "Block DNS over TLS"
# Block DNS over QUIC (DoQ) on UDP port 853
iptables -A FORWARD -i lan -p udp --dport 853 \
-j REJECT --reject-with icmp-port-unreachable \
-m comment --comment "Block DNS over QUIC"
# Block known DNS over HTTPS (DoH) providers
# Google DNS
iptables -A FORWARD -i lan -d 8.8.8.8 -p tcp --dport 443 -j REJECT \
-m comment --comment "Block Google DoH"
iptables -A FORWARD -i lan -d 8.8.4.4 -p tcp --dport 443 -j REJECT \
-m comment --comment "Block Google DoH"
# Cloudflare DNS
iptables -A FORWARD -i lan -d 1.1.1.1 -p tcp --dport 443 -j REJECT \
-m comment --comment "Block Cloudflare DoH"
iptables -A FORWARD -i lan -d 1.0.0.1 -p tcp --dport 443 -j REJECT \
-m comment --comment "Block Cloudflare DoH"
# Quad9 DNS
iptables -A FORWARD -i lan -d 9.9.9.9 -p tcp --dport 443 -j REJECT \
-m comment --comment "Block Quad9 DoH"
iptables -A FORWARD -i lan -d 149.112.112.112 -p tcp --dport 443 -j REJECT \
-m comment --comment "Block Quad9 DoH"
# Optional: Log DNS bypass attempts for monitoring
# iptables -A FORWARD -i lan -p udp --dport 53 -j LOG --log-prefix "DNS-BYPASS: " --log-level warning
# iptables -A FORWARD -i lan -p tcp --dport 853 -j LOG --log-prefix "DoT-ATTEMPT: " --log-level warning
'';
# Clean up QoS rules when firewall stops
@ -218,6 +270,10 @@
# Clear mangle table rules
iptables -t mangle -F FORWARD 2>/dev/null || true
# Clear NAT rules for DNS interception
iptables -t nat -D PREROUTING -i lan -p udp --dport 53 ! -s 192.168.0.1 -j DNAT --to-destination 192.168.0.1:53 2>/dev/null || true
iptables -t nat -D PREROUTING -i lan -p tcp --dport 53 ! -s 192.168.0.1 -j DNAT --to-destination 192.168.0.1:53 2>/dev/null || true
'';
};
useNetworkd = true;