help mirroring mariadb mysql database

enriluis

Hi,

I’m planning to set up a Mailcow backup server and need to replicate and keep the user database (including credentials) updated. Here’s what I’ve done so far:
Modified SQL_PORT=13306 in my configuration.
Verified that MySQL/MariaDB is running on 0.0.0.0:13306 inside Docker.
Confirmed I can connect locally from the host itself.

The Problem:
When trying to connect from another machine on the same network, I get a timeout error—even though the port appears open.

If it were a MySQL permissions issue, I’d expect an authentication prompt or access denied error, but it doesn’t even get that far.
nc -zv confirms the port is listening, but connections from remote machines time out.
What I’ve Checked:
Firewall rules (iptables/UFW) allow traffic on port 13306.
Docker’s port mapping (13306:3306) seems correct.
Local connections work ex (telnet 127.0.0.1 13306 succeeds), nc show the port
Question:
What else could be blocking remote access? Could this be a Docker networking issue, or is there something specific to Mailcow’s mariadb container or iptables configuration I might have missed?

Any help would be greatly appreciated!

DocFraggle

enriluis I’m planning to set up a Mailcow backup server

enriluis I need an active-active setup because some users will use one server or the other

Ok, that’s not what you said in your first post 😒
As the script’s name says, or creates a cold standby server which isn’t intended to be used actively

DocFraggle

You could also just use the cold standby script to create an 1:1 replica:

https://docs.mailcow.email/backup_restore/b_n_r-coldstandby/

Or did you use this script?

enriluis

DocFraggle Oh yes, I will try. I was looking into it, and I think it will be helpful. Thanks!

Can I use imapsync with this setup? I need an active-active setup because some users will use one server or the other, but at the same time, it can act as a backup server. The most important thing is to keep the mailboxes synchronized.

Currently, I’m using a manually installed and configured setup with Postfix, Dovecot, and MySQL etc etc. I keep both the mailbox account/password database replicated and the mailboxes synchronized.

I will try to configure Dovecot in Mailcow to make synchronization possible, but I haven’t reached that point yet. I’ll tackle that later, but I need to get past this stage first.

enriluis

DocFraggle sorry, sorry my english, I didn’t phrase my question correctly initially, but the main goal are keep two mailcow/dovecot instances synchronized with imapsync, to do that i need the user account synchronized too.
I’m going steep by steep,I already have two Mailcow instances deployed and configured.
The cold standby script could have been helpful for the initial setup (though I’m using different Mailcow directories based on hostnames, which isn’t a problem), My current challenge is synchronizing the MariaDB tables/databases - while I can handle this part, I first need to establish the connection

enriluis

the real question is. can i connect to to mariadb database form some host on local lan?
can some one point me to the right direction?
thanks!

DocFraggle

Show us the output of

netstat -tulpen

on your second (backup) host

enriluis

DocFraggle

from the host respond. but no from other machines on same network, i’m review itables rules and all seem to be ok