diff --git a/bundles/dhcpd/metadata.py b/bundles/dhcpd/metadata.py
index 896d27d..bc0b253 100644
--- a/bundles/dhcpd/metadata.py
+++ b/bundles/dhcpd/metadata.py
@@ -56,13 +56,13 @@ def get_listen_interfaces(metadata):
 )
 def iptables(metadata):
     rules = set()
-    for _, subnet in node.metadata.get('dhcpd/subnets', {}).items():
+    for subnet in node.metadata.get('dhcpd/subnets', {}).values():
         rules.add('iptables -A INPUT -i {} -p udp --dport 67:68 -j ACCEPT'.format(subnet['interface']))
 
     return {
         'iptables': {
             'bundle_rules': {
-                # iptables bundle relies on this being a list.
+                # can't use port_rules here. We're generating interface based rules here.
                 'dhcpd': sorted(list(rules)),
             },
         }
diff --git a/bundles/icinga2/metadata.py b/bundles/icinga2/metadata.py
index 6434909..265da64 100644
--- a/bundles/icinga2/metadata.py
+++ b/bundles/icinga2/metadata.py
@@ -1,6 +1,8 @@
 from json import loads
 from os.path import join
 
+from bundlewrap.metadata import atomic
+
 defaults = {
     'apt': {
         'repos': {
@@ -100,25 +102,13 @@ def add_users_from_json(metadata):
 
 
 @metadata_reactor.provides(
-    'iptables/bundle_rules/icinga2',
+    'iptables/port_rules/5665',
 )
 def iptables(metadata):
-    identifiers = metadata.get('icinga2/restrict-to', set())
-    rules = set()
-
-    if identifiers:
-        for identifier in sorted(identifiers):
-            resolved = repo.libs.tools.resolve_identifier(repo, identifier)
-
-            for address in resolved['ipv4']:
-                rules.add(f'iptables -A INPUT -p tcp -s {address} --dport 5665 -j ACCEPT')
-    else:
-        rules.add('iptables -A INPUT -p tcp --dport 5665 -j ACCEPT')
-
     return {
         'iptables': {
-            'bundle_rules': {
-                'icinga2': list(sorted(rules)),
+            'port_rules': {
+                '5665': atomic(metadata.get('icinga2/restrict-to', set())),
             },
         },
     }
diff --git a/bundles/iptables/metadata.py b/bundles/iptables/metadata.py
new file mode 100644
index 0000000..40c5539
--- /dev/null
+++ b/bundles/iptables/metadata.py
@@ -0,0 +1,51 @@
+@metadata_reactor.provides(
+    'iptables/bundle_rules/iptables',
+)
+def port_rules_to_iptables(metadata):
+    # Using this, bundles can simply set up port based rules. This
+    # reactor will then take care of converting those rules to actual
+    # iptables rules
+    ruleset = set()
+
+    # Plese note we do not set any defaults for ports. Bundles are
+    # expected to know themselves which default to use.
+    for portdef, targets in metadata.get('iptables/port_rules', {}).items():
+        if '/' in portdef:
+            port, proto = portdef.split('/', 2)
+
+            if proto not in {'udp'}:
+                raise Exception(f'iptables/port_rules: illegal identifier {portdef} in metadata for {node.name}')
+        else:
+            port = portdef
+            proto = 'tcp'
+
+        for target in targets:
+            if port == '*' and target == '*':
+                raise Exception('iptables/port_rules: setting both port and target to * is unsupported')
+
+            comment = f'-m comment --comment "iptables port_rules {target}"'
+
+            if port != '*':
+                port_str = f'--dport {port}'
+            else:
+                port_str = ''
+
+            if target == '*':
+                ruleset.add(f'iptables_both -A INPUT -p {proto} {port_str} {comment} -j ACCEPT')
+            else:
+                resolved = repo.libs.tools.resolve_identifier(repo, target)
+
+                for address in resolved['ipv4']:
+                    ruleset.add(f'iptables -A INPUT -p {proto} -s {address} {port_str} {comment} -j ACCEPT')
+
+                for address in resolved['ipv6']:
+                    ruleset.add(f'ip6tables -A INPUT -p {proto} -s {address} {port_str} {comment} -j ACCEPT')
+
+    return {
+        'iptables': {
+            'bundle_rules': {
+                # order does not matter here.
+                'iptables': list(sorted(ruleset)),
+            },
+        },
+    }
diff --git a/bundles/netdata/metadata.py b/bundles/netdata/metadata.py
index 2446657..d51d2ff 100644
--- a/bundles/netdata/metadata.py
+++ b/bundles/netdata/metadata.py
@@ -1,3 +1,5 @@
+from bundlewrap.metadata import atomic
+
 defaults = {
     'apt': {
         'packages': {
@@ -17,25 +19,13 @@ defaults = {
 
 
 @metadata_reactor.provides(
-    'iptables/bundle_rules/netdata',
+    'iptables/port_rules/19999',
 )
 def iptables(metadata):
-    identifiers = metadata.get('netdata/restrict-to', set())
-    rules = set()
-
-    if identifiers:
-        for identifier in sorted(identifiers):
-            resolved = repo.libs.tools.resolve_identifier(repo, identifier)
-
-            for address in resolved['ipv4']:
-                rules.add(f'iptables -A INPUT -p tcp -s {address} --dport 19999 -j ACCEPT')
-    else:
-        rules.add('iptables -A INPUT -p tcp --dport 19999 -j ACCEPT')
-
     return {
         'iptables': {
-            'bundle_rules': {
-                'netdata': list(sorted(rules)),
+            'port_rules': {
+                '19999': atomic(metadata.get('netdata/restrict-to', set('*'))),
             },
         },
     }
diff --git a/bundles/nginx/metadata.py b/bundles/nginx/metadata.py
index 0b7e73b..2402abc 100644
--- a/bundles/nginx/metadata.py
+++ b/bundles/nginx/metadata.py
@@ -1,3 +1,5 @@
+from bundlewrap.metadata import atomic
+
 defaults = {
     'apt': {
         'repos': {
@@ -150,31 +152,15 @@ def monitoring(metadata):
 
 
 @metadata_reactor.provides(
-    'iptables/bundle_rules/nginx',
+    'iptables/port_rules/80',
+    'iptables/port_rules/443',
 )
 def iptables(metadata):
-    identifiers = metadata.get('nginx/restrict-to', set())
-    rules = set()
-
-    if identifiers:
-        for identifier in sorted(identifiers):
-            resolved = repo.libs.tools.resolve_identifier(repo, identifier)
-
-            for address in resolved['ipv4']:
-                rules.add(f'iptables -A INPUT -p tcp -s {address} --dport 80 -j ACCEPT')
-                rules.add(f'iptables -A INPUT -p tcp -s {address} --dport 443 -j ACCEPT')
-
-            for address in resolved['ipv6']:
-                rules.add(f'ip6tables -A INPUT -p tcp -s {address} --dport 80 -j ACCEPT')
-                rules.add(f'ip6tables -A INPUT -p tcp -s {address} --dport 443 -j ACCEPT')
-    else:
-        rules.add('iptables_both -A INPUT -p tcp --dport 80 -j ACCEPT')
-        rules.add('iptables_both -A INPUT -p tcp --dport 443 -j ACCEPT')
-
     return {
         'iptables': {
-            'bundle_rules': {
-                'nginx': list(sorted(rules)),
+            'port_rules': {
+                '80': atomic(metadata.get('nginx/restrict-to', set('*'))),
+                '443': atomic(metadata.get('nginx/restrict-to', set('*'))),
             },
         },
     }
diff --git a/bundles/transmission/metadata.py b/bundles/transmission/metadata.py
index 10d44ea..dfe8d68 100644
--- a/bundles/transmission/metadata.py
+++ b/bundles/transmission/metadata.py
@@ -1,3 +1,5 @@
+from bundlewrap.metadata import atomic
+
 defaults = {
     'apt': {
         'packages': {
@@ -34,37 +36,15 @@ defaults = {
 
 
 @metadata_reactor.provides(
-    'iptables/bundle_rules/transmission',
+    'iptables/port_rules',
 )
 def iptables(metadata):
-    identifiers = metadata.get('transmission/restrict-to', set())
-    rules = set()
-
-    rules.add('iptables_both -A INPUT -p udp --dport {} -j ACCEPT'.format(
-        metadata.get('transmission/config/peer-port'),
-    ))
-    rules.add('iptables_both -A INPUT -p tcp --dport {} -j ACCEPT'.format(
-        metadata.get('transmission/config/peer-port'),
-    ))
-
-    if identifiers:
-        for identifier in sorted(identifiers):
-            resolved = repo.libs.tools.resolve_identifier(repo, identifier)
-
-            for address in resolved['ipv4']:
-                rules.add('iptables -A INPUT -p tcp -s {} --dport {} -j ACCEPT'.format(
-                    address,
-                    metadata.get('transmission/config/rpc-port'),
-                ))
-    else:
-        rules.add('iptables -A INPUT -p tcp --dport {} -j ACCEPT'.format(
-            metadata.get('transmission/config/rpc-port'),
-        ))
-
     return {
         'iptables': {
-            'bundle_rules': {
-                'transmission': list(sorted(rules)),
+            'port_rules': {
+                str(metadata.get('transmission/config/peer-port')): set('*'),
+                str(metadata.get('transmission/config/peer-port')) + '/udp': set('*'),
+                str(metadata.get('transmission/config/rpc-port')): atomic(metadata.get('transmission/restrict-to', set('*'))),
             },
         },
     }
diff --git a/bundles/unbound/metadata.py b/bundles/unbound/metadata.py
index c417911..a950996 100644
--- a/bundles/unbound/metadata.py
+++ b/bundles/unbound/metadata.py
@@ -1,3 +1,5 @@
+from bundlewrap.metadata import atomic
+
 defaults = {
     'apt': {
         'packages': {
@@ -38,28 +40,14 @@ def cpu_cores_to_config_values(metadata):
 
 
 @metadata_reactor.provides(
-    'iptables/bundle_rules/unbound',
+    'iptables/port_rules',
 )
 def iptables(metadata):
-    identifiers = metadata.get('unbound/restrict-to', set())
-    rules = set()
-
-    if identifiers:
-        for identifier in sorted(identifiers):
-            resolved = repo.libs.tools.resolve_identifier(repo, identifier)
-
-            for address in resolved['ipv4']:
-                rules.add(f'iptables -A INPUT -p tcp -s {address} --dport 53 -j ACCEPT')
-                rules.add(f'iptables -A INPUT -p udp -s {address} --dport 53 -j ACCEPT')
-
-            for address in resolved['ipv6']:
-                rules.add(f'ip6tables -A INPUT -p tcp -s {address} --dport 53 -j ACCEPT')
-                rules.add(f'ip6tables -A INPUT -p udp -s {address} --dport 53 -j ACCEPT')
-
     return {
         'iptables': {
-            'bundle_rules': {
-                'unbound': list(sorted(rules)),
+            'port_rules': {
+                '53': atomic(metadata.get('unbound/restrict-to', set())),
+                '53/udp': atomic(metadata.get('unbound/restrict-to', set())),
             },
         },
     }
diff --git a/groups/os.py b/groups/os.py
index 729a741..cce9359 100644
--- a/groups/os.py
+++ b/groups/os.py
@@ -39,6 +39,16 @@ groups['linux'] = {
         'backup-client': {
             'server': 'franzi-home.kunbox.net:2022',
         },
+        'iptables': {
+            'port_rules': {
+                '*': {
+                    'ovh.icinga2',
+                },
+                '*/udp': {
+                    'ovh.icinga2',
+                },
+            },
+        },
     },
     'pip_command': 'pip3',
 }