T160: Rebase and fixes for NAT64

 - Update the base (rebase)
 - Move include/nat64-protocol.xml.i => include/nat64/protocol.xml.i
 - Delete unwanted `write_json`, use `write_file` instead
 - Remove unnecessary deleting of default values for tagNodes T2665
 - Add smoketest

Example:
```
set interfaces ethernet eth0 address '192.168.122.14/24'
set interfaces ethernet eth0 address '192.168.122.10/24'
set interfaces ethernet eth2 address '2001:db8::1/64'

set nat64 source rule 100 source prefix '64:ff9b::/96'
set nat64 source rule 100 translation pool 10 address '192.168.122.10'
set nat64 source rule 100 translation pool 10 port '1-65535'
```

5 files changed, 108 insertions, 37 deletions

diff --git a/interface-definitions/include/nat64-protocol.xml.i b/interface-definitions/include/nat64/protocol.xml.i
index 9432e6a87..a640873b5 100644
--- a/interface-definitions/include/nat64-protocol.xml.i
+++ b/interface-definitions/include/nat64/protocol.xml.i
@@ -1,4 +1,4 @@
-<!-- include start from nat64-protocol.xml.i -->
+<!-- include start from nat64/protocol.xml.i -->
 <node name="protocol">
   <properties>
     <help>Apply translation address to a specfic protocol</help>
diff --git a/interface-definitions/nat64.xml.in b/interface-definitions/nat64.xml.in
index 1522395e4..baf13e6cb 100644
--- a/interface-definitions/nat64.xml.in
+++ b/interface-definitions/nat64.xml.in
@@ -66,7 +66,7 @@
                       #include <include/generic-description.xml.i>
                       #include <include/generic-disable-node.xml.i>
                       #include <include/nat-translation-port.xml.i>
-                      #include <include/nat64-protocol.xml.i>
+                      #include <include/nat64/protocol.xml.i>
                       <leafNode name="address">
                         <properties>
                           <help>IPv4 address or prefix to translate to</help>
diff --git a/python/vyos/utils/file.py b/python/vyos/utils/file.py
index 2b1f23b34..9f27a7fb9 100644
--- a/python/vyos/utils/file.py
+++ b/python/vyos/utils/file.py
@@ -83,20 +83,6 @@ def read_json(fname, defaultonfailure=None):
             return defaultonfailure
         raise e
 
-def write_json(fname, data, indent=2, defaultonfailure=None):
-    """
-    encode data to json and write to a file
-    should defaultonfailure be not None, it is returned on failure to write
-    """
-    import json
-    try:
-        with open(fname, 'w') as f:
-            json.dump(data, f, indent=indent)
-    except Exception as e:
-        if defaultonfailure is not None:
-            return defaultonfailure
-        raise e
-
 def chown(path, user, group):
     """ change file/directory owner """
     from pwd import getpwnam
diff --git a/smoketest/scripts/cli/test_nat64.py b/smoketest/scripts/cli/test_nat64.py
new file mode 100755
index 000000000..b5723ac7e
--- /dev/null
+++ b/smoketest/scripts/cli/test_nat64.py
@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2023 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import json
+import os
+import unittest
+
+from base_vyostest_shim import VyOSUnitTestSHIM
+from vyos.configsession import ConfigSessionError
+from vyos.utils.process import cmd
+from vyos.utils.dict import dict_search
+
+base_path = ['nat64']
+src_path = base_path + ['source']
+
+jool_nat64_config = '/run/jool/instance-100.json'
+
+
+class TestNAT64(VyOSUnitTestSHIM.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        super(TestNAT64, cls).setUpClass()
+
+        # ensure we can also run this test on a live system - so lets clean
+        # out the current configuration :)
+        cls.cli_delete(cls, base_path)
+
+    def tearDown(self):
+        self.cli_delete(base_path)
+        self.cli_commit()
+        self.assertFalse(os.path.exists(jool_nat64_config))
+
+    def test_snat64(self):
+        rule = '100'
+        translation_rule = '10'
+        prefix_v6 = '64:ff9b::/96'
+        pool = '192.0.2.10'
+        pool_port = '1-65535'
+
+        self.cli_set(src_path + ['rule', rule, 'source', 'prefix', prefix_v6])
+        self.cli_set(
+            src_path
+            + ['rule', rule, 'translation', 'pool', translation_rule, 'address', pool]
+        )
+        self.cli_set(
+            src_path
+            + ['rule', rule, 'translation', 'pool', translation_rule, 'port', pool_port]
+        )
+        self.cli_commit()
+
+        # Load the JSON file
+        with open(f'/run/jool/instance-{rule}.json', 'r') as json_file:
+            config_data = json.load(json_file)
+
+        # Assertions based on the content of the JSON file
+        self.assertEqual(config_data['instance'], f'instance-{rule}')
+        self.assertEqual(config_data['framework'], 'netfilter')
+        self.assertEqual(config_data['global']['pool6'], prefix_v6)
+        self.assertTrue(config_data['global']['manually-enabled'])
+
+        # Check the pool4 entries
+        pool4_entries = config_data.get('pool4', [])
+        self.assertIsInstance(pool4_entries, list)
+        self.assertGreater(len(pool4_entries), 0)
+
+        for entry in pool4_entries:
+            self.assertIn('protocol', entry)
+            self.assertIn('prefix', entry)
+            self.assertIn('port range', entry)
+
+            protocol = entry['protocol']
+            prefix = entry['prefix']
+            port_range = entry['port range']
+
+            if protocol == 'ICMP':
+                self.assertEqual(prefix, pool)
+                self.assertEqual(port_range, pool_port)
+            elif protocol == 'UDP':
+                self.assertEqual(prefix, pool)
+                self.assertEqual(port_range, pool_port)
+            elif protocol == 'TCP':
+                self.assertEqual(prefix, pool)
+                self.assertEqual(port_range, pool_port)
+            else:
+                self.fail(f'Unexpected protocol: {protocol}')
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)
diff --git a/src/conf_mode/nat64.py b/src/conf_mode/nat64.py
index d4df479ac..a8b90fb11 100755
--- a/src/conf_mode/nat64.py
+++ b/src/conf_mode/nat64.py
@@ -21,6 +21,7 @@ import os
 import re
 
 from ipaddress import IPv6Network
+from json import dumps as json_write
 
 from vyos import ConfigError
 from vyos import airbag
@@ -28,7 +29,7 @@ from vyos.config import Config
 from vyos.configdict import dict_merge
 from vyos.configdict import is_node_changed
 from vyos.utils.dict import dict_search
-from vyos.utils.file import write_json
+from vyos.utils.file import write_file
 from vyos.utils.kernel import check_kmod
 from vyos.utils.process import cmd
 from vyos.utils.process import run
@@ -40,27 +41,12 @@ JOOL_CONFIG_DIR = "/run/jool"
 
 
 def get_config(config: Config | None = None) -> None:
-    """ """
     if config is None:
         config = Config()
 
     base = ["nat64"]
     nat64 = config.get_config_dict(base, key_mangling=("-", "_"), get_first_key=True)
 
-    # T2665: we must add the tagNode defaults individually until this is
-    # moved to the base class
-    for direction in ["source"]:
-        if direction in nat64:
-            default_values = defaults(base + [direction, "rule"])
-            if "rule" in nat64[direction]:
-                for rule in nat64[direction]["rule"]:
-                    nat64[direction]["rule"][rule] = dict_merge(
-                        default_values, nat64[direction]["rule"][rule]
-                    )
-
-                    # Only support netfilter for now
-                    nat64[direction]["rule"][rule]["mode"] = "netfilter"
-
     base_src = base + ["source", "rule"]
 
     # Load in existing instances so we can destroy any unknown
@@ -95,7 +81,6 @@ def get_config(config: Config | None = None) -> None:
 
 
 def verify(nat64) -> None:
-    """ """
     if not nat64:
         # no need to verify the CLI as nat64 is going to be deactivated
         return
@@ -103,7 +88,7 @@ def verify(nat64) -> None:
     if dict_search("source.rule", nat64):
         # Ensure only 1 netfilter instance per namespace
         nf_rules = filter(
-            lambda i: "deleted" not in i and i["mode"] == "netfilter",
+            lambda i: "deleted" not in i and i.get('mode') == "netfilter",
             nat64["source"]["rule"].values(),
         )
         next(nf_rules, None)  # Discard the first element
@@ -138,7 +123,6 @@ def verify(nat64) -> None:
 
 
 def generate(nat64) -> None:
-    """ """
     os.makedirs(JOOL_CONFIG_DIR, exist_ok=True)
 
     if dict_search("source.rule", nat64):
@@ -183,11 +167,10 @@ def generate(nat64) -> None:
                 if pool4:
                     config["pool4"] = pool4
 
-            write_json(f"{JOOL_CONFIG_DIR}/{name}.json", config)
+            write_file(f'{JOOL_CONFIG_DIR}/{name}.json', json_write(config, indent=2))
 
 
 def apply(nat64) -> None:
-    """ """
     if not nat64:
         return