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A Service record (SRV record) is a specification of data in the Domain Name System (DNS) defining the location | A Service record ('''SRV record''') is a specification of data in the Domain Name System ('''DNS''') defining the location (i.e. the hostname and port number) of servers for specified services. It is defined in [http://tools.ietf.org/html/rfc2782 RFC 2782]. | ||
XMPP | == Ports == | ||
=== Very important === | |||
* <span style="color:#FF0000">XMPP uses 5222 ('''C2S''') and 5269 ('''S2S''') ports in TCP only ([http://xmpp.org/rfcs/rfc6120.html RFC 6120]).</span> | |||
=== If used === | |||
* STUN uses 3478 port in TCP/UDP and STUNS (STUN over TLS) uses 5349 port in TCP only ([http://tools.ietf.org/html/rfc5389 RFC 5389]). | |||
* TURN uses 3478 port in TCP/UDP and TURNS (TURN over TLS) uses 5349 port in TCP only ([http://tools.ietf.org/html/rfc5766 RFC 5766], [http://tools.ietf.org/html/rfc5928 RFC 5928]). | |||
== Record format == | == Record format == | ||
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_service._proto.name TTL class SRV priority weight port target | _service._proto.name TTL class SRV priority weight port target | ||
* ''service'': the symbolic name of the desired service. | * '''service''': the symbolic name of the desired service. | ||
* ''proto'': the transport protocol of the desired service; this is usually either TCP or UDP. | * '''proto''': the transport protocol of the desired service; this is usually either TCP or UDP. | ||
* ''name'': the domain name for which this record is valid. | * '''name''': the domain name for which this record is valid. | ||
* ''TTL'': standard DNS time to live field. | * '''TTL''': standard DNS time to live field. | ||
* ''class'': standard DNS class field (this is always ''IN''). | * '''class''': standard DNS class field (this is always '''IN'''). | ||
* ''priority'': the priority of the target host, lower value means more preferred. | * '''priority''': the priority of the target host, lower value means more preferred. | ||
* ''weight'': A relative weight for records with the same priority. | * '''weight''': A relative weight for records with the same priority. | ||
* ''port'': the TCP or UDP port on which the service is to be found. | * '''port''': the TCP or UDP port on which the service is to be found. | ||
* ''target'': the canonical hostname of the machine providing the service. | * '''target''': the canonical hostname of the machine providing the service. | ||
== XMPP SRV records == | == XMPP SRV records == | ||
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_xmpp-server._tcp.example.net. 86400 IN SRV 15 0 5269 backup.example.net. | _xmpp-server._tcp.example.net. 86400 IN SRV 15 0 5269 backup.example.net. | ||
The XMPP domain is example.net and the principal server is server1.example.net which used 50% after server2.example.net 30%, server3.example.net 10%, server4.example.net 10% too, if | The XMPP domain is example.net and the principal server is server1.example.net which used 50% after server2.example.net 30%, server3.example.net 10%, server4.example.net 10% too, if server1 is down, server2, server3 and server4 will work, if servers 1/2/3/4 are down, backup will work. | ||
== Retrieving SRV records == | === Retrieving XMPP SRV records === | ||
$ dig SRV _xmpp-client._tcp.example.net | $ dig SRV _xmpp-client._tcp.example.net | ||
$ dig SRV _xmpp-server._tcp.example.net | $ dig SRV _xmpp-server._tcp.example.net | ||
== STUN SRV records == | |||
_stun._tcp.example.net. TTL IN SRV priority weight port target | |||
_stun._udp.example.net. TTL IN SRV priority weight port target | |||
_stuns._tcp.example.net. TTL IN SRV priority weight port target | |||
=== Example 1 === | |||
_stun._tcp.example.net. 86400 IN SRV 5 0 3478 example.net. | |||
_stun._udp.example.net. 86400 IN SRV 5 0 3478 example.net. | |||
_stuns._tcp.example.net. 86400 IN SRV 5 0 5349 example.net. | |||
The STUN domain is example.net and the server is example.net. | |||
=== Example 2 === | |||
_stun._tcp.example.net. 86400 IN SRV 5 0 3478 server.example.net. | |||
_stun._udp.example.net. 86400 IN SRV 5 0 3478 server.example.net. | |||
_stuns._tcp.example.net. 86400 IN SRV 5 0 5349 server.example.net. | |||
The STUN domain is example.net and the server is server.example.net. | |||
=== Example 3 === | |||
_stun._tcp.example.net. 86400 IN SRV 5 50 3478 server1.example.net. | |||
_stun._tcp.example.net. 86400 IN SRV 10 30 3478 server2.example.net. | |||
_stun._tcp.example.net. 86400 IN SRV 10 10 3478 server3.example.net. | |||
_stun._tcp.example.net. 86400 IN SRV 10 10 3478 server4.example.net. | |||
_stun._tcp.example.net. 86400 IN SRV 15 0 3478 backup.example.net. | |||
_stun._udp.example.net. 86400 IN SRV 5 50 3478 server1.example.net. | |||
_stun._udp.example.net. 86400 IN SRV 10 30 3478 server2.example.net. | |||
_stun._udp.example.net. 86400 IN SRV 10 10 3478 server3.example.net. | |||
_stun._udp.example.net. 86400 IN SRV 10 10 3478 server4.example.net. | |||
_stun._udp.example.net. 86400 IN SRV 15 0 3478 backup.example.net. | |||
_stuns._tcp.example.net. 86400 IN SRV 5 50 5349 server1.example.net. | |||
_stuns._tcp.example.net. 86400 IN SRV 10 30 5349 server2.example.net. | |||
_stuns._tcp.example.net. 86400 IN SRV 10 10 5349 server3.example.net. | |||
_stuns._tcp.example.net. 86400 IN SRV 10 10 5349 server4.example.net. | |||
_stuns._tcp.example.net. 86400 IN SRV 15 0 5349 backup.example.net. | |||
The XMPP domain is example.net and the principal server is server1.example.net which used 50% after server2.example.net 30%, server3.example.net 10%, server4.example.net 10% too, if server1 is down, server2, server3 and server4 will work, if servers 1/2/3/4 are down, backup will work. | |||
=== Retrieving STUN SRV records === | |||
$ dig SRV _stun._tcp.example.net | |||
$ dig SRV _stun._udp.example.net | |||
$ dig SRV _stuns._tcp.example.net | |||
== TURN SRV records == | |||
_turn._tcp.example.net. TTL IN SRV priority weight port target | |||
_turn._udp.example.net. TTL IN SRV priority weight port target | |||
_turns._tcp.example.net. TTL IN SRV priority weight port target | |||
=== Example 1 === | |||
_turn._tcp.example.net. 86400 IN SRV 5 0 3478 example.net. | |||
_turn._udp.example.net. 86400 IN SRV 5 0 3478 example.net. | |||
_turns._tcp.example.net. 86400 IN SRV 5 0 5349 example.net. | |||
The TURN domain is example.net and the server is example.net. | |||
=== Example 2 === | |||
_turn._tcp.example.net. 86400 IN SRV 5 0 3478 server.example.net. | |||
_turn._udp.example.net. 86400 IN SRV 5 0 3478 server.example.net. | |||
_turns._tcp.example.net. 86400 IN SRV 5 0 5349 server.example.net. | |||
The TURN domain is example.net and the server is server.example.net. | |||
=== Example 3 === | |||
_turn._tcp.example.net. 86400 IN SRV 5 50 3478 server1.example.net. | |||
_turn._tcp.example.net. 86400 IN SRV 10 30 3478 server2.example.net. | |||
_turn._tcp.example.net. 86400 IN SRV 10 10 3478 server3.example.net. | |||
_turn._tcp.example.net. 86400 IN SRV 10 10 3478 server4.example.net. | |||
_turn._tcp.example.net. 86400 IN SRV 15 0 3478 backup.example.net. | |||
_turn._udp.example.net. 86400 IN SRV 5 50 3478 server1.example.net. | |||
_turn._udp.example.net. 86400 IN SRV 10 30 3478 server2.example.net. | |||
_turn._udp.example.net. 86400 IN SRV 10 10 3478 server3.example.net. | |||
_turn._udp.example.net. 86400 IN SRV 10 10 3478 server4.example.net. | |||
_turn._udp.example.net. 86400 IN SRV 15 0 3478 backup.example.net. | |||
_turns._tcp.example.net. 86400 IN SRV 5 50 5349 server1.example.net. | |||
_turns._tcp.example.net. 86400 IN SRV 10 30 5349 server2.example.net. | |||
_turns._tcp.example.net. 86400 IN SRV 10 10 5349 server3.example.net. | |||
_turns._tcp.example.net. 86400 IN SRV 10 10 5349 server4.example.net. | |||
_turns._tcp.example.net. 86400 IN SRV 15 0 5349 backup.example.net. | |||
The XMPP domain is example.net and the principal server is server1.example.net which used 50% after server2.example.net 30%, server3.example.net 10%, server4.example.net 10% too, if server1 is down, server2, server3 and server4 will work, if servers 1/2/3/4 are down, backup will work. | |||
=== Retrieving TURN SRV records === | |||
$ dig SRV _turn._tcp.example.net | |||
$ dig SRV _turn._udp.example.net | |||
$ dig SRV _turns._tcp.example.net | |||
== External links == | |||
* [http://tools.ietf.org/html/rfc2782 RFC 2782: A DNS RR for specifying the location of services (DNS SRV)] | |||
* [http://xmpp.org/rfcs/rfc6120.html RFC 6120: Extensible Messaging and Presence Protocol (XMPP): Core] | |||
* [http://tools.ietf.org/html/rfc5389 RFC 5389: Session Traversal Utilities for NAT (STUN)] | |||
* [http://tools.ietf.org/html/rfc5766 RFC 5766: Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)] | |||
* [http://tools.ietf.org/html/rfc5928 RFC 5928: Traversal Using Relays around NAT (TURN) Resolution Mechanism] |
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