Add new api option force_no_cert (#124)

* Add new option force_no_cert

Connect to a router without a certificate by using ADH ciphers.
This can be useful when setting up a device.

* Changelog

* Update plugins/doc_fragments/api.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update changelogs/fragments/124-api.yml

Co-authored-by: Felix Fontein <felix@fontein.de>

Co-authored-by: Felix Fontein <felix@fontein.de>

README.md

@@ -113,6 +113,7 @@ Example playbook:
       password: "{{ password }}"
       username: "{{ username }}"
       tls: true
+      force_no_cert: false
       validate_certs: true
       validate_cert_hostname: true
       ca_path: /path/to/ca-certificate.pem

changelogs/fragments/124-api.yml

@@ -0,0 +1,3 @@
+minor_changes:
+  - api* modules - Add new option ``force_no_cert`` to connect with ADH ciphers
+    (https://github.com/ansible-collections/community.routeros/pull/124).

docs/docsite/rst/api-guide.rst

@@ -107,6 +107,7 @@ Setting up encryption
 
 It is recommended to always use ``tls: true`` when connecting with the API, even if you are only connecting to the device through a trusted network. The following options control how TLS/SSL is used:
 
+:force_no_cert: Setting to ``true`` connects to the device without a certificate. **This is discouraged to use in production and is susceptible to Man-in-the-Middle attacks**, but might be useful when setting the device up. The default value is ``false``.
 :validate_certs: Setting to ``false`` disables any certificate validation. **This is discouraged to use in production**, but is needed when setting the device up. The default value is ``true``.
 :validate_cert_hostname: Setting to ``false`` (default) disables hostname verification during certificate validation. This is needed if the hostnames specified in the certificate do not match the hostname used for connecting (usually the device's IP). It is recommended to set up the certificate correctly and set this to ``true``; the default ``false`` is chosen for backwards compatibility to an older version of the module.
 :ca_path: If you are not using a commerically trusted CA certificate to sign your device's certificate, or have not included your CA certificate in Python's truststore, you need to point this option to the CA certificate.

plugins/doc_fragments/api.py

@@ -46,6 +46,17 @@ options:
       - RouterOS api port. If I(tls) is set, port will apply to TLS/SSL connection.
       - Defaults are C(8728) for the HTTP API, and C(8729) for the HTTPS API.
     type: int
+  force_no_cert:
+    description:
+      - Set to C(true) to connect without a certificate when I(tls=true).
+      - See also I(validate_certs).
+      - B(Note:) this forces the use of anonymous Diffie-Hellman (ADH) ciphers. The protocol is susceptible
+        to Man-in-the-Middle attacks, because the keys used in the exchange are not authenticated.
+        Instead of simply connecting without a certificate to "make things work" have a look at
+        I(validate_certs) and I(ca_path).
+    type: bool
+    default: false
+    version_added: 2.4.0
   validate_certs:
     description:
       - Set to C(false) to skip validation of TLS certificates.

plugins/module_utils/api.py

@@ -41,6 +41,7 @@ def api_argument_spec():
         hostname=dict(type='str', required=True),
         port=dict(type='int'),
         tls=dict(type='bool', default=False, aliases=['ssl']),
+        force_no_cert=dict(type='bool', default=False),
         validate_certs=dict(type='bool', default=True),
         validate_cert_hostname=dict(type='bool', default=False),
         ca_path=dict(type='path'),
@@ -49,7 +50,7 @@ def api_argument_spec():
     )
 
 
-def _ros_api_connect(module, username, password, host, port, use_tls, validate_certs, validate_cert_hostname, ca_path, encoding, timeout):
+def _ros_api_connect(module, username, password, host, port, use_tls, force_no_cert, validate_certs, validate_cert_hostname, ca_path, encoding, timeout):
     '''Connect to RouterOS API.'''
     if not port:
         if use_tls:
@@ -68,7 +69,10 @@ def _ros_api_connect(module, username, password, host, port, use_tls, validate_c
         if use_tls:
             ctx = ssl.create_default_context(cafile=ca_path)
             wrap_context = ctx.wrap_socket
-            if not validate_certs:
+            if force_no_cert:
+                ctx.check_hostname = False
+                ctx.set_ciphers("ADH:@SECLEVEL=0")
+            elif not validate_certs:
                 ctx.check_hostname = False
                 ctx.verify_mode = ssl.CERT_NONE
             elif not validate_cert_hostname:
@@ -101,6 +105,7 @@ def create_api(module):
         module.params['hostname'],
         module.params['port'],
         module.params['tls'],
+        module.params['force_no_cert'],
         module.params['validate_certs'],
         module.params['validate_cert_hostname'],
         module.params['ca_path'],