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https://github.com/GrapheneOS/infrastructure.git
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8c929f02ac
Since our primary servers using SSH to mirror their TLS certificates to replicas are now allowlisted, we can use a stricter block size than we could with the PerSourceMaxStartups approach in sshd.
95 lines
2.8 KiB
Plaintext
95 lines
2.8 KiB
Plaintext
#!/usr/bin/nft -f
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flush ruleset
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table inet filter {
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define ip-allowlist-ssh = {
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127.0.0.1,
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51.222.156.101, # 0.grapheneos.org
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167.114.114.114, # 0.releases.grapheneos.org
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}
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define ip6-allowlist-ssh = {
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::1,
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2607:5300:205:200::29c6, # 0.grapheneos.org
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2607:5300:201:3100::6210, # 0.releases.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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chain prerouting-raw {
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type filter hook prerouting priority raw
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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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iif lo notrack accept
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# drop packets to address not configured on incoming interface (strong host model)
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fib daddr . iif type != { local, broadcast, multicast } counter drop
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tcp dport { 80, 443 } notrack accept
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tcp dport 22 tcp flags syn notrack accept
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meta l4proto { icmp, ipv6-icmp } notrack accept
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}
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chain output-raw {
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type filter hook output priority raw
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oif lo notrack accept
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tcp sport { 80, 443 } notrack accept
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meta l4proto { icmp, ipv6-icmp } notrack accept
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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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iif lo tcp dport 22 tcp flags syn ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } reject with tcp reset
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iif lo tcp dport 22 tcp flags syn ip6 saddr != $ip6-allowlist-ssh add @ip6-connlimit-ssh { ip6 saddr and ffff:ffff:ffff:ffff:ffff:: ct count over 1 } reject with tcp reset
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iif lo accept
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tcp dport { 80, 443 } accept
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meta l4proto { icmp, ipv6-icmp } accept
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ct state vmap { established : accept, related : accept, new : goto graceful-reject }
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tcp dport 22 ip saddr @ip-connlimit-ssh reject with tcp reset
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tcp dport 22 ip6 saddr and ffff:ffff:ffff:ffff:ffff:: @ip6-connlimit-ssh reject with tcp reset
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tcp dport 22 synproxy mss 1460 wscale 7 timestamp sack-perm
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}
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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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chain output {
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type filter hook output priority filter
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oif lo goto output-internal
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skuid != { root, systemd-network, unbound, chrony, http } counter goto graceful-reject
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}
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chain output-internal {
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skuid unbound meta l4proto { tcp, udp } th sport 53 th dport >= 1024 accept
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skuid chrony meta l4proto { tcp, udp } th sport >= 1024 th dport 53 accept
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skuid != root counter goto graceful-reject
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accept
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}
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chain graceful-reject {
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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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}
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}
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