Transport public net to different location ans source route backtraffic via gre

hosts/carbon/configuration.nix

@@ -32,9 +32,16 @@
     { address = "10.152.0.1"; prefixLength = 32; } # Anycast
   ];
   # Network
+  ## Uplink
   networking.interfaces.enp1s0.useDHCP = true;
-  networking.interfaces.enp2s0.ipv6.addresses = [ { address = "fd00:152:152:4::1"; prefixLength = 64; } ];
-  networking.interfaces.enp2s0.ipv4.addresses = [ { address = "10.152.4.1"; prefixLength = 24; } ];
+  ## Local Network
+  networking.interfaces.enp2s0.ipv6.addresses = [
+    { address = "fd00:152:152:4::1"; prefixLength = 64; }
+    { address = "2a01:4f8:1c0c:8221::1"; prefixLength = 64; } # public IPs for local network
+  ];
+  networking.interfaces.enp2s0.ipv4.addresses = [
+    { address = "10.152.4.1"; prefixLength = 24; }
+  ];
 
   networking.nat = {
     enableIPv6 = true;
@@ -72,19 +79,93 @@
 
   clerie.gre-tunnel = {
     enable = true;
+    ipv6= {
+      gre-gatekeeper6 = {
+        remote = "fd00:152:152:101::1";
+        local = (lib.head config.networking.interfaces.lo.ipv6.addresses).address;
+        address = "fd00:153:153:201::2/64";
+      };
+    };
     ipv4 = {
-      gre-gatekeeper = {
+      gre-gatekeeper4 = {
         remote = "10.152.101.1";
         local = (lib.head config.networking.interfaces.lo.ipv4.addresses).address;
-        address = "169.254.201.2/24";
+        address = "10.153.201.2/24";
       };
     };
   };
 
+  # Routing tables
+  # Table: 10000
+  # - primary routes
+  # Table: 11000
+  # - ospf routes
+  # Table: 20101
+  # - default route to gatekeeper
+  #
+  # We will never use main table anymore
+  petabyte.policyrouting = {
+    enable = true;
+    rules6 = [
+      # main routes first except default route
+      { rule = "lookup main suppress_prefixlength 0"; prio = 10000; }
+      # Prefixes defaulting to gatekeeper
+      { rule = "from 2a01:4f8:1c0c:8221::/64 lookup 20101"; prio = 20000; }
+      { rule = "from 2a01:4f8:1c0c:8221::/64 unreachable"; prio = 20001; }
+      # Everything else defaulting to main table after this
+    ];
+    rules4 = [
+      # main routes first except default route
+      { rule = "lookup main suppress_prefixlength 0"; prio = 10000; }
+      # Prefixes defaulting to gatekeeper
+      #{ rule = "from xxx lookup 20101"; prio = 20000; }
+      # Everything else defaulting to main table after this
+    ];
+  };
+
   services.bird2.enable = true;
   services.bird2.config = ''
   router id ${ (lib.head config.networking.interfaces.lo.ipv4.addresses).address };
 
+  ipv6 table gatekeeper6;
+  ipv4 table gatekeeper4;
+
+  protocol static static_gatekeeper_6 {
+          ipv6 {
+                  table gatekeeper6;
+          };
+          route ::/0 via fd00:153:153:201::1;
+  }
+  protocol static static_gatekeeper_4 {
+          ipv4 {
+                  table gatekeeper4;
+          };
+          route 0.0.0.0/0 via 10.153.201.1;
+  }
+
+  protocol kernel kernel_gatekeeper_6 {
+    ipv6 {
+      table gatekeeper6;
+      export filter {
+        krt_prefsrc=${ (lib.head config.networking.interfaces.lo.ipv6.addresses).address };
+        accept;
+      };
+      import none;
+    };
+    kernel table 20101;
+  }
+  protocol kernel kernel_gatekeeper_4 {
+    ipv4 {
+      table gatekeeper4;
+      export filter {
+        krt_prefsrc=${ (lib.head config.networking.interfaces.lo.ipv4.addresses).address };
+        accept;
+      };
+      import none;
+    };
+    kernel table 20101;
+  }
+
   ipv6 table ospf6;
   ipv4 table ospf4;
 

hosts/gatekeeper/configuration.nix

@@ -124,11 +124,18 @@
 
   clerie.gre-tunnel = {
     enable = true;
+    ipv6= {
+      gre-carbon6 = {
+        remote = "fd00:152:152:104::1";
+        local = (lib.head config.networking.interfaces.lo.ipv6.addresses).address;
+        address = "fd00:153:153:201::1/64";
+      };
+    };
     ipv4 = {
-      gre-carbon = {
+      gre-carbon4 = {
         remote = "10.152.104.1";
         local = (lib.head config.networking.interfaces.lo.ipv4.addresses).address;
-        address = "169.254.201.1/24";
+        address = "10.153.201.1/24";
       };
     };
   };

modules/gre-tunnel/default.nix

@@ -21,7 +21,7 @@ let
 
         script = ''
           ${tunnel.preSetup}
-          ip${optionalString isIPv6 " -6"} tunnel add ${name} mode gre remote ${tunnel.remote} local ${tunnel.local}
+          ip${optionalString isIPv6 " -6"} tunnel add ${name} mode ${optionalString isIPv6 "ip6"}gre remote ${tunnel.remote} local ${tunnel.local}
           ip link set ${name} up
           ip${optionalString isIPv6 " -6"} a add ${tunnel.address} dev ${name}
           ${tunnel.postSetup}