graphene-os-server-infrastr.../nftables-matrix.conf
Daniel Micay c1756f5809 add synproxy/connlimit for ACME/redirect use of HTTP
This makes it easier to maintain and deploy more aggressive DDoS
mitigation when our main HTTPS services are under attack.

Network servers use HTTP for connectivity checks which do not use
keepalive and should also be a good use case for
2024-04-04 12:46:38 -04:00

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#!/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-http {
type ipv4_addr
flags dynamic
}
set ip6-connlimit-http {
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)
fib daddr . iif type != { local, broadcast, multicast } counter drop
tcp dport 443 notrack accept
tcp dport { 22, 80 } tcp flags syn notrack accept
meta l4proto { icmp, ipv6-icmp } notrack accept
}
chain output-raw {
type filter hook output priority raw
oif lo notrack accept
tcp sport 443 notrack accept
meta l4proto { icmp, ipv6-icmp } notrack accept
}
chain input {
type filter hook input priority filter
policy drop
iif lo goto input-loopback
tcp dport 443 accept
meta l4proto { icmp, ipv6-icmp } accept
ct state vmap { established : accept, related : accept, new : goto graceful-reject }
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 ip saddr @ip-connlimit-http counter reject with tcp reset
tcp dport 80 ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-http counter reject with tcp reset
tcp dport { 22, 80 } synproxy mss 1460 wscale 7 timestamp sack-perm
}
chain input-loopback {
tcp dport 22 tcp flags syn ip saddr != $ip-allowlist-ssh add @ip-connlimit-ssh { ip saddr ct count over 1 } counter reject with tcp reset
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 } counter reject with tcp reset
tcp dport 80 tcp flags syn add @ip-connlimit-http { ip saddr ct count over 32 } counter reject with tcp reset
tcp dport 80 tcp flags syn add @ip6-connlimit-http { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
accept
}
chain forward {
type filter hook forward priority filter
policy drop
}
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
}
}