doc: add and update information about TLS

doc/configuration.rst

@@ -839,7 +839,7 @@ of the used certificate:
 .. code-block:: console
 
   ... info: binding to QUIC interface ::1@853
-  ... info: QUIC, certificate public key 0xtdayWpnJh4Py8goi8cei/gXGD4kJQ+HEqcxS++DBw=
+  ... info: QUIC/TLS, certificate public key 0xtdayWpnJh4Py8goi8cei/gXGD4kJQ+HEqcxS++DBw=
 
 .. TIP::
 
@@ -874,10 +874,10 @@ Using :doc:`kdig<man_kdig>` we can verify that the server responds over QUIC:
   ;; version.server.     		CH	TXT
 
   ;; ANSWER SECTION:
-  version.server.     	0	CH	TXT	"Knot DNS 3.3.0"
+  version.server.     	0	CH	TXT	"Knot DNS 3.4.0"
 
   ;; Received 468 B
-  ;; Time 2023-08-15 15:04:36 CEST
+  ;; Time 2024-06-21 08:30:12 CEST
   ;; From ::1@853(QUIC) in 1.1 ms
 
 In this case, :rfc:`opportunistic authentication<9103#section-9.3.1>` was
@@ -1087,6 +1087,62 @@ This mode is recommended if possible.
   Knot DNS uses certificate public key pinning. This approach has much lower
   overhead and in most cases simplifies configuration and certificate management.
 
+.. _DNS_over_TLS:
+
+DNS over TLS
+============
+
+TLS is an encrypted internet transport protocol.
+Knot DNS supports DNS over TLS (DoT) (:rfc:`7858`), including zone transfers (XoT).
+By default, the TCP port `853` is used for DNS over TLS.
+
+There are the same requirements for TLS key and certificate as for :ref:`DNS_over_QUIC`.
+
+In order to listen for incoming requests over TLS, :ref:`interface<server_listen-tls>`
+must be configured.
+
+An example of configuration of listening for DNS over TLS on the loopback interface:
+
+.. code-block:: console
+
+  server:
+    listen-tls: ::1
+
+When the server is started, it logs some interface details and public key pin
+of the used certificate:
+
+.. code-block:: console
+
+  ... info: binding to TLS interface ::1@853
+  ... info: QUIC/TLS, certificate public key 0xtdayWpnJh4Py8goi8cei/gXGD4kJQ+HEqcxS++DBw=
+
+Using :doc:`kdig<man_kdig>` we can verify that the server responds over TLS:
+
+.. code-block:: console
+
+  $ kdig @::1 ch txt version.server +tls
+  ;; TLS session (TLS1.3)-(ECDHE-X25519)-(EdDSA-Ed25519)-(AES-256-GCM)
+  ;; ->>HEADER<<- opcode: QUERY; status: NOERROR; id: 0
+  ;; Flags: qr rd; QUERY: 1; ANSWER: 1; AUTHORITY: 0; ADDITIONAL: 1
+
+  ;; EDNS PSEUDOSECTION:
+  ;; Version: 0; flags: ; UDP size: 1232 B; ext-rcode: NOERROR
+  ;; PADDING: 370 B
+
+  ;; QUESTION SECTION:
+  ;; version.server.     		CH	TXT
+
+  ;; ANSWER SECTION:
+  version.server.     	0	CH	TXT	"Knot DNS 3.4.0"
+
+  ;; Received 468 B
+  ;; Time 2024-06-21 08:31:13 CEST
+  ;; From ::1@853(TLS) in 9.1 ms
+
+Zone transfer configuration and authentication profiles are almost identical
+to :ref:`DNS_over_QUIC`, with the only difference being the enabling of
+:ref:`remote_tls` for the corresponding remotes.
+
 .. _query-modules:
 
 Query modules

doc/doxygen/Doxy.page.h

@@ -27,7 +27,7 @@
  - \ref dname     — Domain name manipulation
  - \ref pkt       — DNS packet manipulation
  - \ref probe     — DNS traffic probe interface
- - \ref quic      — QUIC interface
+ - \ref quic      — QUIC and TLS interface
  - \ref rr        — DNS resource record manipulation
  - \ref rrtype    — DNS resource record types
  - \ref knot-tsig — TSIG operations

doc/introduction.rst

@@ -29,7 +29,7 @@ DNS features:
 * Primary and secondary server operation
 * Internet (IN) and Chaos (CH) classes
 * DNS extension (EDNS0, EDE, EXPIRE)
-* UDP, TCP, and QUIC protocols
+* UDP, TCP, TLS 1.3, and QUIC protocols
 * Zone catalog generation and interpretation
 * Minimal responses
 * Dynamic zone updates
@@ -73,7 +73,7 @@ Remarkable module extensions:
 Remarkable supported networking features:
 
 * TCP Fast Open (client and server)
-* Opportunistic, strict, and mutual authentication profiles over QUIC
+* Opportunistic, strict, and mutual authentication profiles over TLS 1.3 or QUIC
 * High-performance UDP, TCP, and QUIC through AF_XDP processing (on Linux 4.18+)
 * SO_REUSEPORT (on Linux) or SO_REUSEPORT_LB (on FreeBSD 12.0+) on UDP and by choice on TCP
 * Binding to non-local addresses (IP_FREEBIND on Linux, IP_BINDANY/IPV6_BINDANY on FreeBSD)

doc/operation.rst

@@ -1282,12 +1282,12 @@ if the backup was created for only a subset of zones.
    turns off some verification checks, it shouldn't be used in other cases.
 
 .. NOTE::
-   For QUIC, only the auto-generated key is restored. The ``zone-restore``
-   command doesn't restore a user-defined QUIC key and certificate so as to
+   For QUIC/TLS, only the auto-generated key is restored. The ``zone-restore``
+   command doesn't restore a user-defined QUIC/TLS key and certificate so as to
    avoid possible configuration management conflicts and they must be restored
    from the backup (its subdirectory ``quic``) manually. In all cases,
    restart of the Knot server after the restore is necessary for the restored
-   QUIC key/certificate to take effect.
+   QUIC/TLS key/certificate to take effect.
 
 Limitations
 -----------