NixOS-Config/system/server/firewall.nix

{outputs, ...}: {
  # Allow forwarding
  boot.kernel.sysctl."net.ipv4.ip_forward" = 1;

  # Configure firewall
  networking = let
    mailPorts = "{ 25, 143, 465, 587, 993, 4190 }";
  in {
    firewall = {
      allowPing = false;
  
      # Add extra input rules using nftables
      extraInputRules = ''
        ip saddr { ${outputs.ips.localSpan}.0/24, ${outputs.ips.wgSpan}.0/24 } tcp dport 2049 accept comment "Accept NFS"
        ip saddr { ${outputs.ips.pc}, ${outputs.secrets.lunaIP}, ${outputs.secrets.cornIP}, ${outputs.secrets.vertIP} } tcp dport { 1935, 1945 } accept comment "Accept RTMP"
        ip saddr ${outputs.ips.wgSpan}.3 tcp dport ${mailPorts} accept comment "Accept mail"
      '';
    };
  
    # Enable nftables and forwarding
    nftables = {
      tables = {
        forwarding = {
          family = "ip";
          content = ''
            chain PREROUTING {
              type nat hook prerouting priority dstnat; policy accept;
              tcp dport 2211 dnat to ${outputs.ips.pc}:22 comment "SSH to PC"
              tcp dport 2233 dnat to ${outputs.ips.wgSpan}.3:22 comment "SSH to Oracle VM"
              
              udp dport { 27005, 27015, 7777 } dnat to ${outputs.ips.pc} comment "PC Hosted Games"
              
              tcp dport { 58010, 57989, 57984 } dnat to ${outputs.ips.pc} comment "PC Sunshine TCP"
              udp dport { 57998, 57999, 58000 } dnat to ${outputs.ips.pc} comment "PC Sunshine UDP"
              
              tcp dport { 38010, 37989, 37984 } dnat to ${outputs.ips.vm} comment "VM Sunshine TCP"
              udp dport { 37998, 37999, 38000 } dnat to ${outputs.ips.vm} comment "VM Sunshine UDP"
              
              udp dport { 7790, 7791, 7792 } dnat to ${outputs.ips.hx} comment "Deus Ex"
              
              ip saddr ${outputs.secrets.cornIP} tcp dport { 9943, 9944 } dnat to ${outputs.ips.vm} comment "VM ALVR TCP"
              ip saddr ${outputs.secrets.cornIP} udp dport { 9943, 9944 } dnat to ${outputs.ips.vm} comment "VM ALVR UDP"
            }
            chain POSTROUTING {
              type nat hook postrouting priority 100; policy accept;
              oifname "${outputs.ips.netInt}" masquerade
	      iifname "${outputs.ips.netInt}" oifname "${outputs.ips.wgInt}" masquerade comment "Traffic from public to WireGuard"
	      tcp dport ${mailPorts} oifname != "${outputs.ips.wgInt}" drop comment "Send mail"
            }
          '';
        };
      };
    };
  };
}