Using Mattermost and GitLab Omnibus on one server without Domain

Hi all,

i installed a GitLab instance on a Redhat 7 using yum.
I do not have a Domain, so i set the IP adress als external_url:

external_url ‘

GitLab works fine, wenn i access the IP-Address i get my projects listed.

As for mattermost, all i did was to set the mattermost_external_url in gitlab.rb in the same way
to the same IP:

mattermost_external_url ‘

and then i ran

sudo gitlab-ctl reconfigure

As far as i understand the docs, this should be suffucient for mattermost to be available.
According to htop mattermost is running.
I expected mattermost to be available at ‘’,
however i get an ERR_CONNECTION_TIMED_OUT.

Do i have to do anything to access mattermost? (i have not used it ever before)
Is it even possible to run Gitlab and Mattermost on the same machine without using a domain?

Any help is appreciated.

Can some please point me into a direction?

What system did you install mattermost on? If also on RHEL, did you make sure that the firewall was disabled, or that you created a firewall rule to unblock port 8065?

You can verify this with:

telnet x.x.x.x 8065

if it connects, then a firewall is not blocking it. If no connection, then it would mean that it’s not unblocked. Assuming RHEL7 or higher:

firewall-cmd --add-port 8065/tcp --permanent
firewall-cmd --reload

on the server where mattermost is installed.

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At first the firewall-cmd commands gave me an Error:

FirewallD is not running

However after invoking


the commands

firewall-cmd --add-port 8065/tcp --permanent
firewall-cmd --reload

reported a success.

However the telnet invokation still gives me

telnet: connect to address : Connection refused

I assume there is some other firewall running (i did not configure this server),
so i will write again, when i managed to unblock the port somehow.

If the servers are in the same subnet, then it could be another firewall running on this machine, if not nftables, maybe iptables. If a different subnet, then it could be a firewall between the two networks, so in that case it wouldn’t necessarily be something running on the server itself. But whoever set up the server should be able to help sort out the access where necessary so that the port is unblocked.

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I can access mattermost via when connected to the server,
so I guess this port access is really the issue.
I will have someone with deeper firewall knowledge look into it.

Thanks a lot!

Get them to check that port 8065 is not only just bound to localhost ( but also to the IP of the machine itself. Maybe they need to fix the configuration of Mattermost so that the port is accessible via the IP of the server.