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Zulip writes a `rabbitmq.config` configuration file which locks down RabbitMQ to listen only on localhost:5672, as well as the RabbitMQ distribution port, on localhost:25672. The "distribution port" is part of Erlang's clustering configuration; while it is documented that the protocol is fundamentally insecure ([1], [2]) and can result in remote arbitrary execution of code, by default the RabbitMQ configuration on Debian and Ubuntu leaves it publicly accessible, with weak credentials. The configuration file that Zulip writes, while effective, is only written _after_ the package has been installed and the service started, which leaves the port exposed until RabbitMQ or system restart. Ensure that rabbitmq's `/etc/rabbitmq/rabbitmq.config` is written before rabbitmq is installed or starts, and that changes to that file trigger a restart of the service, such that the ports are only ever bound to localhost. This does not mitigate existing installs, since it does not force a rabbitmq restart. [1] https://www.erlang.org/doc/apps/erts/erl_dist_protocol.html [2] https://www.erlang.org/doc/reference_manual/distributed.html#distributed-erlang-system
Zulip overview
Zulip is a powerful, open source group chat application that combines the immediacy of real-time chat with the productivity benefits of threaded conversations. Zulip is used by open source projects, Fortune 500 companies, large standards bodies, and others who need a real-time chat system that allows users to easily process hundreds or thousands of messages a day. With over 700 contributors merging over 500 commits a month, Zulip is also the largest and fastest growing open source group chat project.
Getting started
Click on the appropriate link below. If nothing seems to apply, join us on the Zulip community server and tell us what's up!
You might be interested in:
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Contributing code. Check out our guide for new contributors to get started. Zulip prides itself on maintaining a clean and well-tested codebase, and a stock of hundreds of beginner-friendly issues.
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Contributing non-code. Report an issue, translate Zulip into your language, write for the Zulip blog, or give us feedback. We would love to hear from you, even if you're just trying the product out.
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Supporting Zulip. Advocate for your organization to use Zulip, become a sponsor, write a review in the mobile app stores, or upvote Zulip on product comparison sites.
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Checking Zulip out. The best way to see Zulip in action is to drop by the Zulip community server. We also recommend reading Zulip for open source, Zulip for companies, or Zulip for working groups and part time communities.
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Running a Zulip server. Use a preconfigured DigitalOcean droplet, install Zulip directly, or use Zulip's experimental Docker image. Commercial support is available; see https://zulip.com/plans for details.
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Using Zulip without setting up a server. https://zulip.com offers free and commercial hosting, including providing our paid plan for free to fellow open source projects.
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Participating in outreach programs like Google Summer of Code.
You may also be interested in reading our blog or following us on Twitter. Zulip is distributed under the Apache 2.0 license.