mod_matrix_gw: inet unreach on IPv6 only host #4458
Description
Environment
- ejabberd version: 25.08
- Erlang version:
Erlang (SMP,ASYNC_THREADS) (BEAM) emulator version 15.2.7.2 - OS: Alpine Linux
- Installed from: distro package
Logs from ejabberd.log
2025-09-20 14:54:18.109745+02:00 [debug] <0.555.0>@mod_matrix_gw_s2s:do_get_matrix_host_port/1:467 HTTPRes {error,{failed_connect,[{to_address,{"matrix.org",443}},
{inet,[inet],enetunreach}]}}
Bug description
(Note: I'm running ejabberd on an IPv6 only host)
When trying to interact with a matrix server (eg. matrix.org), it is always unreachable. Trying to message my XMPP user from matrix.org also doesn't work but I see incoming traffic from my webserver and ejabberd_http module directed to matrix federation APIs.
Incoming messages are rejected with:
2025-09-20 15:06:42.680057+02:00 [debug] <0.603.0>@mod_matrix_gw:preprocess_federation_request/2:461 auth failed
I assume because ejabberd can't fetch key material due to the connectivity issues, I'd be happy to attach a longer log for an exchange of trying to start a chat from the matrix side.
Manually testing connectivity to matrix.org with curl works:
curl -s https://matrix-federation.matrix.org/_matrix/federation/v1/version | jq
{
"server": {
"name": "Synapse",
"version": "1.138.0rc1 (b=matrix-org-hotfixes-priv,e9e42af8d9,dirty)"
}
}