From ee2fe873f3c2afdc9b6aa1e9cb62abe6f6cff4cc Mon Sep 17 00:00:00 2001
From: celso <celsochan@disroot.org>
Date: Fri, 13 Dec 2024 00:49:09 -0300
Subject: [PATCH] added openvpn port, forward rules and nat table on its own
 file

---
 defines.nft |  4 ++++
 filter.nft  |  9 ++++++++-
 nat.nft     | 12 ++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 nat.nft

diff --git a/defines.nft b/defines.nft
index 75853f2..17a6691 100644
--- a/defines.nft
+++ b/defines.nft
@@ -1,3 +1,6 @@
+# Networks
+define VPN_SUBNET = 10.8.0.0/24
+
 # TCP only services
 define SSH_PORT1 = 22
 define SSH_PORT2 = 8022
@@ -10,3 +13,4 @@ define DNS_PORT = 53
 # UDP only services
 define DHCP_IN_PORT = 67
 define DHCP_OUT_PORT = 68
+define OPENVPN_PORT = 1194
diff --git a/filter.nft b/filter.nft
index 4d8d8bd..03c934b 100644
--- a/filter.nft
+++ b/filter.nft
@@ -13,7 +13,7 @@ table ip filter {
 	set allowed_udp_ports_in {
 		type inet_service;
 		flags constant;
-		elements = { $DNS_PORT, $DHCP_IN_PORT }
+		elements = { $DNS_PORT, $DHCP_IN_PORT, $OPENVPN_PORT }
 	}
 
 	set allowed_udp_ports_out {
@@ -30,8 +30,13 @@ table ip filter {
 		tcp dport @allowed_tcp_ports accept;
 		udp dport @allowed_udp_ports_in accept;
 	}
+
 	chain forward {
 		type filter hook forward priority filter; policy drop;
+		comment "this routes vpn traffic";
+		ct state related,established accept;
+		iifname "tun0" oifname "eth0" accept;
+
 	}
 
 	chain out {
@@ -40,3 +45,5 @@ table ip filter {
 		oifname "lo" accept;
 	}
 }
+
+include "./nat.nft"
diff --git a/nat.nft b/nat.nft
new file mode 100644
index 0000000..d3b28b5
--- /dev/null
+++ b/nat.nft
@@ -0,0 +1,12 @@
+table nat {
+	chain prerouting {
+		type nat hook prerouting priority 0;
+		comment "this is necessary even if empty";
+	}
+
+	chain postrouting {
+		type nat hook postrouting priority 100;
+		comment "enable NAT for VPN";
+		iifname "tun0" oifname "eth0" ip saddr $VPN_SUBNET masquerade;
+	}
+}