<![CDATA[Enable Matrix Federation on same Cludron server]]>I'd like to propose a change to the default synapse config file. Currently, the federation blacklist blocks any connections from another Matrix instance on the same server:

federation_ip_range_blacklist:
  - '127.0.0.0/8'
  - '10.0.0.0/8'
  - '172.16.0.0/12' # this is blocking the internal conections
  - '192.168.0.0/16'
  - '100.64.0.0/10'
  - '169.254.0.0/16'
  - '::1/128'
  - 'fe80::/64'
  - 'fc00::/7'

Synapse supports additional whitelisting which overrides the blacklist:

ip_range_whitelist:
  - '172.18.0.0/16' # Whitelist the Cloudron's docker network
]]>https://forum.cloudron.io/topic/13821/enable-matrix-federation-on-same-cludron-serverRSS for NodeThu, 14 May 2026 20:25:07 GMTWed, 21 May 2025 13:33:59 GMT60<![CDATA[Reply to Enable Matrix Federation on same Cludron server on Sat, 24 May 2025 07:37:35 GMT]]>https://git.cloudron.io/packages/synapse-app/-/merge_requests/23

]]>https://forum.cloudron.io/post/107624https://forum.cloudron.io/post/107624Sat, 24 May 2025 07:37:35 GMT<![CDATA[Reply to Enable Matrix Federation on same Cludron server on Sat, 24 May 2025 06:09:14 GMT]]>@andreasdueren 😳 Will sync the configs to upstream ones and add the whitelist ...

]]>https://forum.cloudron.io/post/107612https://forum.cloudron.io/post/107612Sat, 24 May 2025 06:09:14 GMT<![CDATA[Reply to Enable Matrix Federation on same Cludron server on Fri, 23 May 2025 17:14:43 GMT]]>I'm not sure, there might be a good argument made fore the existing blocklist. However it made me troubleshoot a federation issue much longer than I wish it would, hence my request here to have the whitelist included if the blacklist is because others might run into similar issues.

]]>https://forum.cloudron.io/post/107606https://forum.cloudron.io/post/107606Fri, 23 May 2025 17:14:43 GMT<![CDATA[Reply to Enable Matrix Federation on same Cludron server on Fri, 23 May 2025 15:28:26 GMT]]>Right, easy to overlook those in the ranges.

Given that we just pre-provision the package with a template of the sample config when we packaged the app, it is safe to adjust those values. In fact the current sample file at https://github.com/element-hq/synapse/blob/develop/docs/sample_config.yaml does not even mention any block/allow listing at all.

]]>https://forum.cloudron.io/post/107603https://forum.cloudron.io/post/107603Fri, 23 May 2025 15:28:26 GMT<![CDATA[Reply to Enable Matrix Federation on same Cludron server on Fri, 23 May 2025 13:55:28 GMT]]>Hi @girish

  1. The 172.16.0.0/12 Range:

    • This CIDR block represents IP addresses from 172.16.0.0 to 172.31.255.255.
    • The /12 means the first 12 bits are fixed for the network portion, leaving 20 bits for host addresses.

  2. Cloudron's Docker Network 172.18.0.0/16:

    • This CIDR block represents IP addresses from 172.18.0.0 to 172.18.255.255.

The range 172.18.0.0 to 172.18.255.255 (Cloudron's Docker network) is a sub-range within 172.16.0.0 to 172.31.255.255.
Since 16 <= 18 <= 31, any IP in 172.18.x.y falls into the 172.16.0.0/12 block.

You are likely looking at 172.18.x.x and 172.16.x.x and thinking they are distinct because the second octet is different. However, the /12 subnet mask on 172.16.0.0 makes it a much larger range that also encompasses 172.18.0.0/16.

]]>https://forum.cloudron.io/post/107600https://forum.cloudron.io/post/107600Fri, 23 May 2025 13:55:28 GMT<![CDATA[Reply to Enable Matrix Federation on same Cludron server on Fri, 23 May 2025 08:50:08 GMT]]>Cloudron's docker network is in 172.18.0.0/16 which afaict is not in the federation_ip_range_blacklist . What am I missing?

]]>https://forum.cloudron.io/post/107581https://forum.cloudron.io/post/107581Fri, 23 May 2025 08:50:08 GMT