From 3e23b80e9cb42b73dd46669f5b67fddcf6686802 Mon Sep 17 00:00:00 2001
From: Daniel Micay <daniel.micay@grapheneos.org>
Date: Mon, 1 Apr 2024 19:40:46 -0400
Subject: [PATCH] move mail server HTTP(S) connection limit to nftables

This has the same reasoning as 9fcac6b105274c308a3c59955b40985f4e60a905
other than these services being used for MTA-STS in addition to ACME and
redirects to the FAQ for the domains.
---
 nftables-mail.conf | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/nftables-mail.conf b/nftables-mail.conf
index 71ae92b..04acd8b 100644
--- a/nftables-mail.conf
+++ b/nftables-mail.conf
@@ -21,6 +21,16 @@ table inet filter {
         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
 
@@ -32,8 +42,8 @@ table inet filter {
         # drop packets to address not configured on incoming interface (strong host model)
         fib daddr . iif type != { local, broadcast, multicast } counter drop
 
-        tcp dport { 25, 80, 443, 465, 993 } notrack accept
-        tcp dport 22 tcp flags syn notrack accept
+        tcp dport { 25, 465, 993 } notrack accept
+        tcp dport { 22, 80, 443 } tcp flags syn notrack accept
         meta l4proto { icmp, ipv6-icmp } notrack accept
     }
 
@@ -41,7 +51,7 @@ table inet filter {
         type filter hook output priority raw
 
         oif lo notrack accept
-        tcp sport { 25, 80, 443, 465, 993 } notrack accept
+        tcp sport { 25, 465, 993 } notrack accept
         meta l4proto { icmp, ipv6-icmp } notrack accept
     }
 
@@ -50,18 +60,22 @@ table inet filter {
         policy drop
 
         iif lo goto input-loopback
-        tcp dport { 25, 80, 443, 465, 993 } accept
+        tcp dport { 25, 465, 993 } 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 22 synproxy mss 1460 wscale 7 timestamp sack-perm
+        tcp dport { 80, 443 } ip saddr @ip-connlimit-http counter reject with tcp reset
+        tcp dport { 80, 443 } ip6 saddr and ffff:ffff:ffff:ffff:: @ip6-connlimit-http counter reject with tcp reset
+        tcp dport { 22, 80, 443 } 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, 443 } tcp flags syn add @ip-connlimit-http { ip saddr ct count over 32 } counter reject with tcp reset
+        tcp dport { 80, 443 } tcp flags syn add @ip6-connlimit-http { ip6 saddr and ffff:ffff:ffff:ffff:: ct count over 32 } counter reject with tcp reset
         accept
     }