2022-06-29 10:53:07 -04:00
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#!/usr/bin/nft -f
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flush ruleset
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table inet filter {
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2024-04-18 10:40:29 -04:00
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define ip-anycast = 198.251.90.93
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2024-03-27 03:08:21 -04:00
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define ip-allowlist-ssh = {
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198.98.53.141, # 0.ns2.grapheneos.org
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}
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define ip6-allowlist-ssh = {
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2605:6400:10:102e:95bc:89ef:2e7f:49bb, # 0.ns2.grapheneos.org
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}
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set ip-connlimit-ssh {
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type ipv4_addr
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flags dynamic
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}
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set ip6-connlimit-ssh {
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type ipv6_addr
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flags dynamic
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}
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2024-03-31 22:07:58 -04:00
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set ip-connlimit-main {
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2024-03-28 10:34:59 -04:00
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type ipv4_addr
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flags dynamic
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}
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2024-03-31 22:07:58 -04:00
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set ip6-connlimit-main {
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2024-03-28 10:34:59 -04:00
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type ipv6_addr
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flags dynamic
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}
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2022-06-29 10:53:07 -04:00
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chain prerouting-raw {
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type filter hook prerouting priority raw
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2024-04-26 10:42:45 -04:00
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policy drop
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2022-06-29 10:53:07 -04:00
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2024-03-23 11:18:02 -04:00
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# drop packets without a reverse path (strict reverse path filtering)
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fib saddr . iif oif missing counter drop
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2022-07-21 17:31:16 -04:00
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iif lo notrack accept
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2024-03-24 13:27:55 -04:00
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# drop packets to address not configured on incoming interface (strong host model)
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2024-04-11 09:49:50 -04:00
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#
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# ordered after accepting loopback to permit using external IPs via loopback
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2024-03-24 13:27:55 -04:00
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fib daddr . iif type != { local, broadcast, multicast } counter drop
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2024-04-15 23:54:17 -04:00
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udp dport 53 notrack accept
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2024-04-19 13:25:42 -04:00
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tcp dport 22 ip daddr $ip-anycast drop
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2024-03-24 15:22:00 -04:00
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2024-04-11 09:56:30 -04:00
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# handle new TCP connections beyond rate limit via synproxy to avoid conntrack table exhaustion
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2024-04-26 16:30:49 -04:00
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tcp dport { 22, 53, 80, 443, 853 } tcp flags syn limit rate over 1024/second burst 1024 packets counter notrack accept
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2024-04-11 09:56:30 -04:00
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2024-04-26 10:42:45 -04:00
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meta l4proto { tcp, udp } accept
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2024-03-24 16:23:54 -04:00
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meta l4proto { icmp, ipv6-icmp } notrack accept
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2022-06-29 10:53:07 -04:00
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}
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chain input {
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type filter hook input priority filter
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policy drop
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2024-04-11 11:49:22 -04:00
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tcp dport { 22, 53, 80, 443, 853 } goto input-tcp-service
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2024-04-23 02:14:07 -04:00
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ct state vmap { invalid : drop, established : accept, related : accept, new : drop, untracked: accept }
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2024-04-11 11:49:22 -04:00
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}
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chain input-tcp-service {
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2024-04-11 11:59:19 -04:00
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iif lo goto input-tcp-service-loopback
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2024-04-11 10:19:39 -04:00
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# for synproxy, SYN is untracked and first ACK is invalid which are handled via fallthrough
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2024-04-23 03:29:52 -04:00
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ct state vmap { established : goto input-tcp-service-established, related : accept, new : goto input-tcp-service-new }
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2022-06-29 10:53:07 -04:00
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2024-03-28 23:28:34 -04:00
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tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
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tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
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2024-03-31 22:07:58 -04:00
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tcp dport { 53, 80, 443, 853 } ip saddr @ip-connlimit-main counter reject with tcp reset
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tcp dport { 53, 80, 443, 853 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
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2024-04-11 11:49:22 -04:00
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synproxy mss 1460 wscale 7 timestamp sack-perm
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2022-06-29 10:53:07 -04:00
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}
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2024-04-11 11:59:19 -04:00
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chain input-tcp-service-new {
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2024-04-10 09:29:56 -04:00
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tcp dport 22 ip saddr @ip-connlimit-ssh counter reject with tcp reset
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tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh counter reject with tcp reset
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tcp dport { 53, 80, 443, 853 } ip saddr @ip-connlimit-main counter reject with tcp reset
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tcp dport { 53, 80, 443, 853 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-main counter reject with tcp reset
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accept
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}
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2024-04-11 15:59:07 -04:00
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# add connections established without synproxy to connection limit sets with limits enforced
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2024-04-11 11:59:19 -04:00
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chain input-tcp-service-established {
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2024-04-10 09:29:56 -04:00
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ct mark 0x1 accept
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tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
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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
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tcp dport { 53, 80, 443, 853 } add @ip-connlimit-main { ip saddr ct count over 16 } counter reject with tcp reset
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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
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ct mark set 0x1 accept
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}
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2024-04-11 15:59:07 -04:00
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# add connections established with synproxy to connection limit sets with limits enforced
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2024-04-11 11:59:19 -04:00
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chain input-tcp-service-loopback {
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2024-04-05 13:36:09 -04:00
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tcp flags != syn accept
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tcp dport 22 ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
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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
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tcp dport { 53, 80, 443, 853 } add @ip-connlimit-main { ip saddr ct count over 16 } counter reject with tcp reset
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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
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2024-04-10 09:29:56 -04:00
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ct mark set 0x1 accept
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2024-03-28 13:23:13 -04:00
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}
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2022-06-29 10:53:07 -04:00
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chain forward {
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type filter hook forward priority filter
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policy drop
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}
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2024-04-05 19:14:05 -04:00
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chain output-raw {
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type filter hook output priority raw
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2024-04-17 15:03:13 -04:00
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oif lo goto output-raw-loopback
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skuid != { root, systemd-network, unbound, chrony, http, powerdns, geoipupdate } counter goto graceful-reject
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2024-04-05 19:14:05 -04:00
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udp sport 53 notrack accept
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meta l4proto { icmp, ipv6-icmp } notrack accept
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}
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2024-04-17 15:03:13 -04:00
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chain output-raw-loopback {
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skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 notrack accept
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skuid { chrony, geoipupdate } meta l4proto { tcp, udp } th sport >= 1024 th dport 53 notrack accept
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2024-01-19 13:44:47 -05:00
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2024-04-17 15:03:13 -04:00
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skuid powerdns meta l4proto tcp th sport 54 th dport >= 1024 notrack accept
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skuid http meta l4proto tcp th sport >= 1024 th dport 54 notrack accept
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2022-07-25 20:03:09 -04:00
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2024-04-17 15:03:13 -04:00
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skuid powerdns meta l4proto tcp th sport 81 th dport >= 1024 notrack accept
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2023-02-14 01:19:19 -05:00
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2024-03-27 12:31:09 -04:00
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skuid != root counter goto graceful-reject
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2024-04-17 15:03:13 -04:00
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notrack accept
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2022-07-25 20:03:09 -04:00
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}
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2024-03-27 12:31:09 -04:00
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chain graceful-reject {
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2022-06-29 20:18:51 -04:00
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meta l4proto udp reject
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meta l4proto tcp reject with tcp reset
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reject
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2022-06-29 10:53:07 -04:00
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}
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}
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