man: document which IP ports resolved listens on, and what for

Fixes: #23045
This commit is contained in:
Lennart Poettering 2023-06-07 12:47:09 +02:00 committed by Zbigniew Jędrzejewski-Szmek
parent d1579f0b70
commit bef84b81a4

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@ -442,6 +442,27 @@ search foobar.com barbar.com
</variablelist>
</refsect1>
<refsect1>
<title>IP Ports</title>
<para>The <command>systemd-resolved</command> service listens on the following IP ports:</para>
<itemizedlist>
<listitem><para>Port 53 on IPv4 addresses 127.0.0.53 and 127.0.0.54 (both are on the local loopback
interface <literal>lo</literal>). This is the local DNS stub, as discussed above. Both UDP and TCP are
covered.</para></listitem>
<listitem><para>Port 5353 on all local addresses, both IPv4 and IPv6 (0.0.0.0 and ::0), for
MulticastDNS on UDP. Note that even though the socket is bound to all local interfaces via the selected
"wildcard" IP addresses, the incoming datagrams are filtered by the network interface they are coming
in on, and separate MulticastDNS link-local scopes are maintained for each, taking into consideration
whether MulticastDNS is enabled for the interface or not.</para></listitem>
<listitem><para>Port 5355 on all local addresses, both IPv4 and IP6 (0.0.0.0 and ::0), for LLMNR, on
both TCP and UDP. As with MulticastDNS filtering by incoming network interface is applied.</para></listitem>
</itemizedlist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>