This is a feature release and is also the first release of the mosquitto project from the Eclipse Foundation umbrella. The code is now dual licenced under the EPL. The EDL and BSD 3 clause license are essentially identical so if you were happy with the BSD license then you should be happy with the EDL.

Files distributed will remain in the same place but will in some cases also be available on the Eclipse download servers.

Important changes

Websockets support in the broker.
Bridge behaviour on the local broker has changed due to the introduction of the local_* options. This may affect you if you are using authentication and/or ACLs with bridges.
The default TLS behaviour has changed to accept all of TLS v1.2, v1.1 and v1.0, rather than only one version of the protocol. It is still possible to restrict a listener to a single version of TLS.
The Python client has been removed now that the Eclipse Paho Python client has had a release.
When a durable client reconnects, its queued messages are now checked against ACLs in case of a change in username/ACL state since it last connected.
New use_username_as_clientid option on the broker, for preventing hijacking of a client id.
The client library and clients now have experimental SOCKS5 support.
Wildcard TLS certificates are now supported for bridges and clients.
The clients have support for config files with default options.
Client and client libraries have support for MQTT v3.1.1.
Bridge support for MQTT v3.1.1.

Broker

Websockets support in the broker.
Add local_clientid, local_username, local_password for bridge connections to authenticate to the local broker.
Default TLS mode now accepts TLS v1.2, v1.1 and v1.0.
Support for ECDHE-ECDSA family ciphers.
Fix bug #1324411, which could have had unexpected consequences for delayed messages in rare circumstances.
Add support for session present in CONNACK messages for MQTT v3.1.1.
Remove strict protocol #ifdefs.
Change $SYS/broker/clients/active -> $SYS/broker/clients/connected
Change $SYS/broker/clients/inactive -> $SYS/broker/clients/disconnected
When a durable client reconnects, its queued messages are now checked against ACLs in case of a change in username/ACL state since it last connected.
libuuid is used to generate client ids, where it is available, when an MQTT v3.1.1 client connects with a zero length client id.
Anonymous clients are no longer accidently disconnected from the broker after a SIGHUP.
mosquitto_passwd now supports -b (batch mode) to allow the password to be provided at the command line.
Removed $SYS/broker/changeset. This was intended for use with debugging, but in practice is of no use.
Add support for use_username_as_clientid which can be used with authentication to restrict ownership of client ids and hence prevent one client disconnecting another by using the same client id.
When require_certificate was false, the broker was incorrectly asking for a certificate (but not checking it). This caused problems with some clients and has been fixed so the broker no longer asks.
When using syslog logging on non-Windows OSs, it is now possible to specify the logging facility to one of local0-7 instead of the default "daemon".
The bridge_attempt_unsubscribe option has been added, to allow the sending of UNSUBSCRIBE requests to be disabled for topics with "out" direction. Closes bug #456899.
Wildcard TLS certificates are now supported for bridges.
Support for "hour" client expiration lengths for the persistent_client_expiration option. Closes bug #425835.
Bridge support for MQTT v3.1.1.
Root privileges are now dropped after starting listeners and loading certificates/private keys, to allow private keys to have their permissions restricted to the root user only. Closes bug #452914.
Usernames and topics given in ACL files can now include a space. Closes bug #431780.
Fix hang if pattern acl contains a %u but an anonymous client connect. Closes bug #455402.
Fix man page installation with cmake. Closes bug #458843.
When using log_dest file the output file is now flushed periodically.

Clients

Both clients can now load default configuration options from a file.
Add -C option to mosquitto_sub to allow the client to quit after receiving a certain count of messages. Closes bug #453850.
Add --proxy SOCKS5 support for both clients.
Pub client supports setting its keepalive. Closes bug #454852.
Add support for config files with default options.
Add support for MQTT v3.1.1.

Client library

Add experimental SOCKS5 support.
mosquitto_loop_forever now quits after a fatal error, rather than blindly retrying.
SRV support is now not compiled in by default.
Wildcard TLS certificates are now supported.
mosquittopp now has a virtual destructor. Closes bug #452915.
Add support for MQTT v3.1.1.
Don't quit mosquitto_loop_forever() if broker not available on first connect. Closes bug #453293, but requires more work.

Dependencies

This release introduces two new dependencies, libwebsockets and libuuid. Both are optional. libuuid comes from the e2fsprogs project and allows the broker to generate random client ids for MQTT v.3.1.1. The libwebsockets dependency can use either libwebsockets 1.3 or 1.2.x, with 1.3 being the preferred choice.