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To celebrate the new mosquitto logo, stickers are now available:


If you would like to obtain some stickers for yourself you have two options.

The first is to get in touch and I’ll send you some for a small contribution. This contribution is to cover the cost of the stickers plus postage: (cost of postage)+N*£0.45, where N is the number of sheets of 6 stickers that you want. Cost of postage for a letter can be calculated using the Royal Mail price finder, but should be £1.05 for destinations outside of the UK. Please also consider Paypal fees using a fees calculator to calculate the final sum. So for a single sheet of stickers posted internationally, the cost would be £1.76 including paypal fees. Two sheets would be £2.23.

The second option is to buy a full sticker book through This can be done very easily by navigating to This allows you to easily order a sticker book of 90 stickers with either the colour or blue monochrome stickers, or a mix of both.

There is a third option – get in touch to say why you deserve some stickers and maybe we’ll send you some. We’re looking for things that make us say “wow!” If you will be sending your sticker to space, getting mosquitto on television or using MQTT in your Formula 1 technology, these are all things that would exciting to see with a mosquitto sticker in place. If you want to give out stickers at a local IoT related event or similar that’s great, but we’d ask that you make a small donation. It’s only a small cost for you, but there are many people in your situation and it becomes a noticeable cost for the project.

Please do post links of your kit sporting any stickers you use!

The first round of the logo contest has closed and we now need to shortlist 6 designers. A selection of 20 logos have been chosen out of the 100 entrants and you are invited to vote on them and make comments. If you like a particular logo but not the colour, or like an idea behind the logo but not another element then please say so.

The links for voting (please do look at them all) are:

Logo contest

We have initiated a paid contest to create a new logo for the Mosquitto project.

If you have graphics design skills or know someone who has,  please head over to the link below to see the design brief and submit your idea.


Repository moved to github

The mosquitto repository is now hosted on github: This is now the canonical location for mosquitto development work.

Bug reports should also be made on github and the existing bug reports will be migrated over shortly.

The documentation still needs updating with the new location and processes, so please do be patient with regards that.

Contributions can now be made through a github pull request. If you want to contribute a bug fix, please base your work off the “fixes” branch, if you are developing a new feature please use the “develop” branch.

Here’s to a new stage in the mosquitto project!

Version 1.4.8 released

This is a security bugfix release. Any users of the “mount_point” feature are strongly advised to upgrade because versions prior to 1.4.8 allow clients to inject messages outside of their mount_point through the use of a Will.


  • Wills published by clients connected to a listener with mount_point defined
    now correctly obey the mount point. This was a potential security risk
    because it allowed clients to publish messages outside of their restricted
    mount point. This is only affects brokers where the mount_point option is in
    use. Closes #487178.
  • Fix detection of broken connections on Windows. Closes #485143.
  • Close stdin etc. when daemonised. Closes #485589.
  • Fix incorrect detection of FreeBSD and OpenBSD. Closes #485131.

Client library

  • mosq->want_write should be cleared immediately before a call to SSL_write,
    to allow clients using mosquitto_want_write() to get accurate results.

Version 1.4.7 released

This is a bugfix release. The changes below include the changes for 1.4.6, which wasn’t announced.


  • Add support for libwebsockets 1.6.

Client library

  • Fix _mosquitto_socketpair() on Windows, reducing the chance of delays when
    publishing. Closes #483979.


  • Fix “mosquitto_pub -l” stripping the final character on a line. Closes

If you want to use TLS certificates you’ve generated using the Let’s Encrypt service, this is how you should configure your listener (replace “” with your own domain of course):

First you need a copy of the root certificate. This will either be the ISRG Root X1, or IdenTrust DST Root CA X3. You need to check which of these root CAs signed the intermediate certificate you are using:

openssl x509 -in /etc/letsencrypt/live/ -noout -issuer

If your intermediate was issued by the ISRG root then use:


Otherwise you should go to to get the DST root certificate. Open a text editor, and paste the contents from that link, surrounding the text with the BEGIN and END lines as below:


pasted content goes here


Then, each time after your script to automatically generate your certificates runs you should also run:

cat /etc/letsencrypt/live/ /etc/letsencrypt/<your root>.pem > /etc/letsencrypt/live/

Then use the following for your mosquitto.conf:

listener 8883
cafile /etc/letsencrypt/live/
certfile /etc/letsencrypt/live/
keyfile /etc/letsencrypt/live/

You need to be aware that current versions of mosquitto never update listener settings when running, so when you regenerate the server certificates you will need to completely restart the broker.

Version 1.4.5 released

This is a bugfix release:


  • Fix possible memory leak if bridge using SSL attempts to connect to a host that is not up.
  • Free unused topic tree elements (fix in 1.4.3 was incomplete). Closes


  • “mosquitto_pub -l” now no longer limited to 1024 byte lines. Closes #478917.

Version 1.4.4 released

This is a bugfix release.

  • Don’t leak sockets when outgoing bridge with multiple addresses cannot connect. Closes #477571.
  • Fix cross compiling of websockets. Closes #475807.
  • Fix memory free related crashes on openwrt and FreeBSD. Closes #475707.
  • Fix excessive calls to message retry check.

The current unreleased libwebsockets master branch defines the VERSION macro in its header files. I believe this to be a bug in libwebsockets.

This bug causes compilation of mosquitto with websockets support to fail.

Please use a released version of libwebsockets, either 1.2, 1.3 or 1.4. Mosquitto will compile with all of these versions.

I do not recommend using an unreleased version of libwebsockets, the project is not shy about making ABI/API incompatible changes between releases so it is impractical to provide support for.