mirror of
https://github.com/vyos/vyos-documentation.git
synced 2025-10-26 08:41:46 +01:00
124 lines
4.4 KiB
ReStructuredText
124 lines
4.4 KiB
ReStructuredText
mDNS Repeater
|
|
-------------
|
|
|
|
Starting with VyOS 1.2 a :abbr:`mDNS (Multicast DNS)` repeater functionality is
|
|
provided. Additional information can be obtained from
|
|
https://en.wikipedia.org/wiki/Multicast_DNS.
|
|
|
|
Multicast DNS uses the reserved address ``224.0.0.251``, which is
|
|
`"administratively scoped"` and does not leave the subnet. mDNS repeater
|
|
retransmits mDNS packets from one interface to other interfaces. This enables
|
|
support for devices using mDNS discovery (like network printers, Apple Airplay,
|
|
Chromecast, various IP based home-automation devices etc) across multiple VLANs.
|
|
|
|
Since the mDNS protocol sends the :abbr:`AA(Authoritative Answer)` records in
|
|
the packet itself, the repeater does not need to forge the source address.
|
|
Instead, the source address is of the interface that repeats the packet.
|
|
|
|
.. note:: You can not run this in a VRRP setup, if multiple mDNS repeaters
|
|
are launched in a subnet you will experience the mDNS packet storm death!
|
|
|
|
Configuration
|
|
=============
|
|
|
|
.. cfgcmd:: set service mdns repeater interface <interface>
|
|
|
|
To enable mDNS repeater you need to configure at least two interfaces so that
|
|
all incoming mDNS packets from one interface configured here can be
|
|
re-broadcasted to any other interface(s) configured under this section.
|
|
|
|
.. cfgcmd:: set service mdns repeater disable
|
|
|
|
mDNS repeater can be temporarily disabled without deleting the service using
|
|
|
|
.. cfgcmd:: set service mdns repeater ip-version <ipv4 | ipv6 | both>
|
|
|
|
mDNS repeater can be enabled either on IPv4 socket or on IPv6 socket or both
|
|
to re-broadcast. By default, mDNS repeater will listen on both IPv4 and IPv6.
|
|
|
|
.. cfgcmd:: set service mdns repeater allow-service <service>
|
|
|
|
mDNS repeater can be configured to re-broadcast only specific services. By
|
|
default, all services are re-broadcasted.
|
|
|
|
.. cfgcmd:: set service mdns repeater browse-domain <domain>
|
|
|
|
Allow listing additional custom domains to be browsed (in addition to the
|
|
default ``local``) so that they can be reflected.
|
|
|
|
.. cfgcmd:: set service mdns repeater cache-entries <entries>
|
|
|
|
Specify how many resource records are cached per interface. Bigger values
|
|
allow mDNS work correctly in large LANs but also increase memory consumption.
|
|
|
|
Defaults to: 4096
|
|
|
|
Firewall recommendations
|
|
========================
|
|
|
|
Unlike typical routed traffic, mDNS packets relayed between interfaces do not
|
|
traverse the FORWARD hook chain in the firewall. Instead, they are processed
|
|
through the following hooks:
|
|
|
|
- **INPUT**: For packets received by the local system
|
|
- **OUTPUT**: For packets sent from the local system
|
|
|
|
To control or allow mDNS packet forwarding via the relay, you must define
|
|
appropriate rules in the INPUT and OUTPUT directions. Rules in the FORWARD
|
|
direction will have no effect on mDNS relay traffic.
|
|
|
|
.. code-block:: none
|
|
|
|
set firewall ipv4 input filter rule 10 action 'accept'
|
|
set firewall ipv4 input filter rule 10 destination address '224.0.0.251'
|
|
set firewall ipv4 input filter rule 10 destination port '5353'
|
|
set firewall ipv4 input filter rule 10 protocol 'udp'
|
|
set firewall ipv4 output filter rule 10 action 'accept'
|
|
set firewall ipv4 output filter rule 10 destination address '224.0.0.251'
|
|
set firewall ipv4 output filter rule 10 destination port '5353'
|
|
set firewall ipv4 output filter rule 10 protocol 'udp'
|
|
|
|
Example
|
|
=======
|
|
|
|
To listen on both `eth0` and `eth1` mDNS packets and also repeat packets
|
|
received on `eth0` to `eth1` (and vice-versa) use the following commands:
|
|
|
|
.. code-block:: none
|
|
|
|
set service mdns repeater interface 'eth0'
|
|
set service mdns repeater interface 'eth1'
|
|
|
|
To allow only specific services, for example ``_airplay._tcp`` or ``_ipp._tcp``,
|
|
(instead of all services) to be re-broadcasted, use the following command:
|
|
|
|
.. code-block:: none
|
|
|
|
set service mdns repeater allow-service '_airplay._tcp'
|
|
set service mdns repeater allow-service '_ipp._tcp'
|
|
|
|
To allow listing additional custom domain, for example
|
|
``openthread.thread.home.arpa``, so that it can reflected in addition to the
|
|
default ``local``, use the following command:
|
|
|
|
.. code-block:: none
|
|
|
|
set service mdns repeater browse-domain 'openthread.thread.home.arpa'
|
|
|
|
.. _`Multicast DNS`: https://en.wikipedia.org/wiki/Multicast_DNS
|
|
|
|
Operation
|
|
=========
|
|
|
|
.. opcmd:: restart mdns repeater
|
|
|
|
Restart mDNS repeater service.
|
|
|
|
.. opcmd:: show log mdns repeater
|
|
|
|
Show logs for mDNS repeater service.
|
|
|
|
.. opcmd:: monitor log mdns repeater
|
|
|
|
Follow the logs for mDNS repeater service.
|