move nftables configuration to a directory

nftables/nftables-attestation.conf

@@ -0,0 +1,139 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 80, 443 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 80, 443 } goto input-tcp-service
+        iif lo accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, http, attestation } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 th dport != 8080 accept
+        skuid { chrony, attestation } meta l4proto { tcp, udp } th sport >= 1024 th sport != 8080 th dport 53 accept
+
+        skuid attestation tcp sport 8080 tcp dport >= 1024 tcp dport != 8080 accept
+        skuid http tcp sport >= 1024 tcp sport != 8080 tcp dport 8080 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}

nftables/nftables-discuss.conf

@@ -0,0 +1,136 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 80, 443 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 80, 443 } goto input-tcp-service
+        iif lo accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, http, flarum, flarum-admin, geoipupdate } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 accept
+        skuid { chrony, http, flarum, flarum-admin, geoipupdate } meta l4proto { tcp, udp } th sport >= 1024 th dport 53 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}

nftables/nftables-mail.conf

@@ -0,0 +1,136 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 25, 80, 443, 465, 993 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 25, 80, 443, 465, 993 } goto input-tcp-service
+        iif lo accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 25, 80, 443, 465, 993 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 25, 80, 443, 465, 993 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 25, 80, 443, 465, 993 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 25, 80, 443, 465, 993 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 25, 80, 443, 465, 993 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 25, 80, 443, 465, 993 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 25, 80, 443, 465, 993 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 25, 80, 443, 465, 993 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, postfix, dovecot, dovenull, http } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 accept
+        skuid { chrony, postfix, opendkim, opendmarc, policyd-spf } meta l4proto { tcp, udp } th sport >= 1024 th dport 53 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}

nftables/nftables-matrix.conf

@@ -0,0 +1,146 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 80, 443 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 80, 443 } goto input-tcp-service
+        iif lo accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, http, synapse, matterbridge } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 th dport != 8008 accept
+        skuid { chrony, synapse, matterbridge } meta l4proto { tcp, udp } th sport >= 1024 th sport != 8008 th dport 53 accept
+
+        skuid postgres udp sport >= 1024 udp sport != 8008 udp dport >= 1024 udp dport != 8008 accept
+
+        skuid synapse tcp sport 8008 tcp dport >= 1024 tcp dport != 8008 accept
+        skuid http tcp sport >= 1024 tcp sport != 8008 tcp dport 8008 accept
+        skuid mjolnir tcp sport >= 1024 tcp sport != 8008 tcp dport 8008 accept
+
+        skuid http tcp sport 443 tcp dport >= 1024 tcp dport != 8008 accept
+        skuid matterbridge tcp sport >= 1024 tcp sport != 8008 tcp dport 443 accept
+        skuid synapse tcp sport >= 1024 tcp sport != 8008 tcp dport 443 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}

nftables/nftables-network.conf

@@ -0,0 +1,141 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+        51.222.159.116, # 0.grapheneos.network
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+        2607:5300:205:200::2584, # 0.grapheneos.network
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 80, 443, 7275 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        udp dport 123 notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 80, 443, 7275 } goto input-tcp-service
+        iif lo accept
+        udp dport 123 accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443, 7275 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443, 7275 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443, 7275 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443, 7275 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443, 7275 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443, 7275 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443, 7275 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443, 7275 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        udp sport 123 notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, http } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 accept
+        skuid { chrony, http } meta l4proto { tcp, udp } th sport >= 1024 th dport 53 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}

nftables/nftables-ns1.conf

@@ -0,0 +1,145 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        udp dport 53 notrack accept
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 53, 80, 443, 853 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 53, 80, 443, 853 } goto input-tcp-service
+        iif lo accept
+        udp dport 53 accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } add @ip-connlimit-main { ip saddr ct count over 16 } counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 16 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } add @ip-connlimit-main { ip saddr ct count over 16 } counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 16 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        udp sport 53 notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, http, powerdns, geoipupdate } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 accept
+        skuid { chrony, geoipupdate } meta l4proto { tcp, udp } th sport >= 1024 th dport 53 accept
+
+        skuid powerdns meta l4proto tcp th sport 54 th dport >= 1024 accept
+        skuid http meta l4proto tcp th sport >= 1024 th dport 54 accept
+
+        skuid powerdns meta l4proto tcp th sport 81 th dport >= 1024 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}

nftables/nftables-ns2.conf

@@ -0,0 +1,150 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+        198.98.53.141, # 0.ns2.grapheneos.org
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+        2605:6400:10:102e:95bc:89ef:2e7f:49bb, # 0.ns2.grapheneos.org
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        # reject SSH packets via anycast IP
+        tcp dport 22 ip daddr 198.251.90.93 reject with tcp reset
+
+        udp dport 53 notrack accept
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 53, 80, 443, 853 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 53, 80, 443, 853 } goto input-tcp-service
+        iif lo accept
+        udp dport 53 accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } add @ip-connlimit-main { ip saddr ct count over 16 } counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 16 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } add @ip-connlimit-main { ip saddr ct count over 16 } counter reject with tcp reset
+        tcp dport { 53, 80, 443, 853 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 16 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        udp sport 53 notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, http, powerdns, geoipupdate } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 accept
+        skuid { chrony, geoipupdate } meta l4proto { tcp, udp } th sport >= 1024 th dport 53 accept
+
+        skuid powerdns meta l4proto tcp th sport 54 th dport >= 1024 accept
+        skuid http meta l4proto tcp th sport >= 1024 th dport 54 accept
+
+        skuid powerdns meta l4proto tcp th sport 81 th dport >= 1024 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}

nftables/nftables-social.conf

@@ -0,0 +1,138 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 80, 443 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 80, 443 } goto input-tcp-service
+        iif lo accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, http, mastodon } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 accept
+        skuid { chrony, mastodon } meta l4proto { tcp, udp } th sport >= 1024 th dport 53 accept
+
+        skuid postgres udp sport >= 1024 udp dport >= 1024 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}

nftables/nftables-web.conf

@@ -0,0 +1,140 @@
+#!/usr/bin/nft -f
+
+flush ruleset
+
+table inet filter {
+    define ip-allowlist-ssh = {
+        127.0.0.1,
+        51.222.156.101, # 0.grapheneos.org
+        167.114.114.114, # 0.releases.grapheneos.org
+    }
+
+    define ip6-allowlist-ssh = {
+        ::1,
+        2607:5300:205:200::29c6, # 0.grapheneos.org
+        2607:5300:201:3100::6210, # 0.releases.grapheneos.org
+    }
+
+    set ip-connlimit-ssh {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-ssh {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    set ip-connlimit-main {
+        type ipv4_addr
+        flags dynamic
+    }
+
+    set ip6-connlimit-main {
+        type ipv6_addr
+        flags dynamic
+    }
+
+    chain prerouting-raw {
+        type filter hook prerouting priority raw
+
+        # drop packets without a reverse path (strict reverse path filtering)
+        fib saddr . iif oif missing counter drop
+
+        iif lo notrack accept
+
+        # drop packets to address not configured on incoming interface (strong host model)
+        #
+        # ordered after accepting loopback to permit using external IPs via loopback
+        fib daddr . iif type != { local, broadcast, multicast } counter drop
+
+        # handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
+        tcp dport { 22, 80, 443 } tcp flags syn limit rate over 1024/second burst 128 packets counter notrack accept
+
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain input {
+        type filter hook input priority filter
+        policy drop
+
+        tcp dport { 22, 80, 443 } goto input-tcp-service
+        iif lo accept
+        meta l4proto { icmp, ipv6-icmp } accept
+        ct state vmap { new : goto graceful-reject, established : accept, related : accept }
+    }
+
+    chain input-tcp-service {
+        iif lo goto input-tcp-service-loopback
+
+        # for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
+        ct state vmap { new : goto input-tcp-service-new, established : goto input-tcp-service-established, related : accept }
+
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        synproxy mss 1460 wscale 7 timestamp sack-perm
+    }
+
+    chain input-tcp-service-new {
+        tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
+        tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-main counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
+        accept
+    }
+
+    # add connections established without synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-established {
+        ct mark 0x1 accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    # add connections established with synproxy to connection limit sets with limits enforced
+    chain input-tcp-service-loopback {
+        tcp flags != syn accept
+        tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
+        tcp dport 22 ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip-connlimit-main { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } add @ip6-connlimit-main { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
+        ct mark set 0x1 accept
+    }
+
+    chain forward {
+        type filter hook forward priority filter
+        policy drop
+    }
+
+    chain output-raw {
+        type filter hook output priority raw
+
+        oif lo notrack accept
+        meta l4proto { icmp, ipv6-icmp } notrack accept
+    }
+
+    chain output {
+        type filter hook output priority filter
+
+        oif lo goto output-loopback
+        skuid != { root, systemd-network, unbound, chrony, http } counter goto graceful-reject
+    }
+
+    chain output-loopback {
+        skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 accept
+        skuid chrony meta l4proto { tcp, udp } th sport >= 1024 th dport 53 accept
+
+        skuid != root counter goto graceful-reject
+        accept
+    }
+
+    chain graceful-reject {
+        meta l4proto udp reject
+        meta l4proto tcp reject with tcp reset
+        reject
+    }
+}