* **Use case 1**: From another MISP server (also called MISP instance), by synchronising two MISP servers.
* **Use case 2**: From a link, by using [Feeds](../managing-feeds).
The example below illustrate the synchronisation between two MISP servers (use case 1).
An organisation B (OrgB) wants to synchronise its MISP server, called ServerB, with the MISP server of an organisation A (Org A), called ServerA. The following steps can be taken to syncronise ServerB with ServerA:
* **Step 3**: [Set up a sync server](#adding-a-server) on MISP ServerB using the key (called Authkey) from the sync user (syncuser@OrgB.ServerA) created on MISP ServerA.
For additional information on the synchronisation process, refer to the [MISP GitHub issues](https://github.com/MISP/MISP/issues), for example, [issue 2595](https://github.com/MISP/MISP/issues/2595).
Click this, if you would like to allow a connection despite the other instance using a self-signed certificate (not recommended). (server certificate file still needed)
Rules are used to limit sharing when synchronising events and attributes, to e.g. events with a given tag, or disabling sharing for events containing a certain Tag.
- with connection issues do a package capture to find out more
- if you have a SSL connection issue to a remote server with a signed by a CA that is not included in OS, make sure the whole certificate path is included in the path.
The following section describes how distribution mechanisms of events and attributes work.
### Distribution settings
The below five distribution settings are available for events and attributes. Descriptions of those settings can be found [here](../using-the-system/#creating-an-event).
* Your organisation only
* This community only
* Connected communities
* All communities
* Sharing group
Events that are not published are only distributed/shared to the local organisations on the same MISP server/instance (within the limit of the distribution model).
Only events that are **published** will be shared with remote organisations on other MISP servers via push/pull mechanisms.
More details on publishing events [here](../using-the-system/#publish-an-event).
A community is composed of the local organisations on a MISP server and the remote organisations connected by the sync users. For more information on the concept of community, refer to an [article on MISP information sharing following ISO/IEC 27010](https://github.com/MISP/misp-compliance/blob/master/ISO_IEC_27010/misp-sharing-information-following-ISO-IEC-27010.md#suitable-data-model), explaining the concept of community.
Specifically, communities are not reversible. Taking the example of <ahref="#misp-server-sync">the above figure</a>, illustrating the synchronisation between two MISP servers, OrgB.ServerB is part of the MISP ServerA community but OrgB.ServerA is not part of MISP ServerB community.
The distribution level of an event is automatically decreased as it is synchronised with other MISP instances, when it was originally set to:
* Community only (to organisation only)
* Connected community (to community only)
It is not decreased when it was originally set to:
* Organisation only
* All communities
* Sharing group
[!] This rule does not apply if “Internal instance” has been checked when creating the server.
As an example, the figure below illustrates two events **e** and **e'** created by OrgA and respectively shared as "This community only" and "Connected communities" and how they propagate in an illustrative MISP set of intances synchronised with each others.
<aname="misp-server-sync"></a><imgsrc="https://github.com/MISP/misp-compliance/blob/master/ISO_IEC_27010/images/misp-compliance-iso-concepts.png"alt="Illustration of MISP organisations and community interactions"style="width: 100%;"/></br>