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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:26:00 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 15:26:00 +0000
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Adding upstream version 5.6.0.upstream/5.6.0upstream
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+.. SPDX-License-Identifier: GPL-3.0-or-later
+
+.. _mod-daf:
+
+DNS Application Firewall
+========================
+
+This module is a high-level interface for other powerful filtering modules and DNS views. It provides an easy interface to apply and monitor DNS filtering rules and a persistent memory for them. It also provides a restful service interface and an HTTP interface.
+
+Example configuration
+---------------------
+
+Firewall rules are declarative and consist of filters and actions. Filters have ``field operator operand`` notation (e.g. ``qname = example.com``), and may be chained using AND/OR keywords. Actions may or may not have parameters after the action name.
+
+.. code-block:: lua
+
+ -- Let's write some daft rules!
+ modules = { 'daf' }
+
+ -- Block all queries with QNAME = example.com
+ daf.add('qname = example.com deny')
+
+ -- Filters can be combined using AND/OR...
+ -- Block all queries with QNAME match regex and coming from given subnet
+ daf.add('qname ~ %w+.example.com AND src = 192.0.2.0/24 deny')
+
+ -- We also can reroute addresses in response to alternate target
+ -- This reroutes 192.0.2.1 to localhost
+ daf.add('src = 127.0.0.0/8 reroute 192.0.2.1-127.0.0.1')
+
+ -- Subnets work too, this reroutes a whole subnet
+ -- e.g. 192.0.2.55 to 127.0.0.55
+ daf.add('src = 127.0.0.0/8 reroute 192.0.2.0/24-127.0.0.0')
+
+ -- This rewrites all A answers for 'example.com' from
+ -- whatever the original address was to 127.0.0.2
+ daf.add('src = 127.0.0.0/8 rewrite example.com A 127.0.0.2')
+
+ -- Mirror queries matching given name to DNS logger
+ daf.add('qname ~ %w+.example.com mirror 127.0.0.2')
+ daf.add('qname ~ example-%d.com mirror 127.0.0.3@5353')
+
+ -- Forward queries from subnet
+ daf.add('src = 127.0.0.1/8 forward 127.0.0.1@5353')
+ -- Forward to multiple targets
+ daf.add('src = 127.0.0.1/8 forward 127.0.0.1@5353,127.0.0.2@5353')
+
+ -- Truncate queries based on destination IPs
+ daf.add('dst = 192.0.2.51 truncate')
+
+ -- Disable a rule
+ daf.disable(2)
+ -- Enable a rule
+ daf.enable(2)
+ -- Delete a rule
+ daf.del(2)
+
+ -- Delete all rules and start from scratch
+ daf.clear()
+
+.. warning:: Only the first matching rule's action is executed. Defining
+ additional actions for the same matching rule, e.g. ``src = 127.0.0.1/8``,
+ will have no effect.
+
+If you're not sure what firewall rules are in effect, see ``daf.rules``:
+
+.. code-block:: text
+
+ -- Show active rules
+ > daf.rules
+ [1] => {
+ [rule] => {
+ [count] => 42
+ [id] => 1
+ [cb] => function: 0x1a3eda38
+ }
+ [info] => qname = example.com AND src = 127.0.0.1/8 deny
+ [policy] => function: 0x1a3eda38
+ }
+ [2] => {
+ [rule] => {
+ [suspended] => true
+ [count] => 123522
+ [id] => 2
+ [cb] => function: 0x1a3ede88
+ }
+ [info] => qname ~ %w+.facebook.com AND src = 127.0.0.1/8 deny...
+ [policy] => function: 0x1a3ede88
+ }
+
+Web interface
+-------------
+
+If you have :ref:`HTTP/2 <mod-http>` loaded, the firewall automatically loads as a snippet.
+You can create, track, suspend and remove firewall rules from the web interface.
+If you load both modules, you have to load `daf` after `http`.
+
+RESTful interface
+-----------------
+
+The module also exports a RESTful API for operations over rule chains.
+
+
+.. csv-table::
+ :header: "URL", "HTTP Verb", "Action"
+
+ "/daf", "GET", "Return JSON list of active rules."
+ "/daf", "POST", "Insert new rule, rule string is expected in body. Returns rule information in JSON."
+ "/daf/<id>", "GET", "Retrieve a rule matching given ID."
+ "/daf/<id>", "DELETE", "Delete a rule matching given ID."
+ "/daf/<id>/<prop>/<val>", "PATCH", "Modify given rule, for example /daf/3/active/false suspends rule 3."
+
+This interface is used by the web interface for all operations, but you can also use it directly
+for testing.
+
+.. code-block:: bash
+
+ # Get current rule set
+ $ curl -s -X GET http://localhost:8453/daf | jq .
+ {}
+
+ # Create new rule
+ $ curl -s -X POST -d "src = 127.0.0.1 pass" http://localhost:8453/daf | jq .
+ {
+ "count": 0,
+ "active": true,
+ "info": "src = 127.0.0.1 pass",
+ "id": 1
+ }
+
+ # Disable rule
+ $ curl -s -X PATCH http://localhost:8453/daf/1/active/false | jq .
+ true
+
+ # Retrieve a rule information
+ $ curl -s -X GET http://localhost:8453/daf/1 | jq .
+ {
+ "count": 4,
+ "active": true,
+ "info": "src = 127.0.0.1 pass",
+ "id": 1
+ }
+
+ # Delete a rule
+ $ curl -s -X DELETE http://localhost:8453/daf/1 | jq .
+ true