Home Linux Setup A Private Server With ownCloud, Kopano And Let’s Encrypt On UCS

Setup A Private Server With ownCloud, Kopano And Let’s Encrypt On UCS

By sk
Published: Updated: 1.5K views

When reading all the horror news today about cyber-attacks and malware, have you ever wished to set up your own server to finally have the greatest possible control over your own data? If yes, you're on the right track! In our previous articles Introduction To Univention Corporate Server and Installation and Configuration of Univention Corporate Server, we talked about the server and IT management solution Univention Corporate Server and how you can install it for business use. This time we take a bit different approach and put together a software bundle around UCS that meets higher security requirements very well and is thus ideal for every "home admin" to build his own private server.

Setup A Private Server With ownCloud, Kopano And Let's Encrypt On Univention Corporate Server

In the following steps, we will show you how to set that up in a few steps and include groupware, mail, and file exchange software. i.e. ownCloud and Kopano apps. Proprietary mail and groupware solutions will therefore become redundant if you like. And with the installation of Let's Encrypt the connections to your UCS server will also be well protected.

First question: Where do I run the server?

Basically, private users confront the same questions as enterprises: „Shall I run the server on my own hardware, in my own “IT center” (or storeroom), or shall I run it on a rented system, hosted somewhere, e.g., a “dedicated server” with a cloud service provider. Before you decide, it is important to ask yourself how you actually intend to use the server.

To rent or not to rent

A rented system involves a small initial investment and is not usually associated with significant bandwidth restrictions. On top, it is easier to adjust it to your requirements. A rented system is practical when you need access from different locations, e.g., when the server is used by all members of your organization who might work somewhere else.

Running your own network

If you run a system on your own network, it first offers you full control over your own data and it also supports additional application scenarios such as a standard file server or the streaming of music and videos to local media players. However, depending on a private Internet connection often is a bottleneck when you want to access the system from outside; even the very latest VDSL connections come with a comparatively low upload capacity. Some Internet providers prevent any access from outside. I therefore recommend to run a few tests before you invest in new hardware.

The steps described below are generally applicable for both options.

What hardware would I need?

UCS has only minor requirements on hardware, so the choice is yours. In principle, older desktop hardware can be suitable, too. However, they are often related to disadvantages in terms of reliability and power consumption if the system runs non-stop. If you decide to invest in a very new system, there are manufacturers offering systems which are suitable to be operated 24/7 (often referred to as “SOHO NAS” (Small or Home Office Network Attached Storage) systems). The HP systems in the MicroServer range and the Low Energy Servers from Thomas-Krenn are here examples.

The purpose determines which size is right for you

The next thing you need to think about is the matter of the system’s size. The setup we present here runs on a system with a smaller CPU and 4 GB RAM without any problems. The number of simultaneous accesses is the critical part. If the number of users or applications increases, you will eventually be needing more capacity. Cloud offers can always be expanded easily. In case you purchase the system, it is thus worth it starting out with already 8 or 16 GB RAM and a CPU with 4 cores.

The hard disk space required for UCS is negligible – 10 GB is more than enough to keep the operating system working for a long time. The decisive factor here is what you intend to do with it, particularly, the amount of data that you save on the system. Please also consider redundancy via mirrored disks (RAID) when purchasing hardware.

IP and DNS Configuration

To access the system from the Internet, you require a public IP address and corresponding DNS entry. If you rent server resources, they supply you with at least an IP address and often also a public domain.

In home networks, the public IP is generally assigned to the private router. This needs to be configured so that it can pass requests on to the local UCS system. How this is done depends on the router itself and possibly on the Internet provider. You can find HowTos for that on the Web for the majority of routers and firewalls. If the private router does not have a public IP, it might be difficult or even impossible to run a publicly accessible server behind it. In case of doubt, please contact your Internet provider or seek further information on the Web.

The next requirement is a publicly resolvable DNS entry, which can be procured from providers of dynamic DNS.

The router takes care of all communication with the DNS provider. we use domain “my-ucs.dnsalias.org” as an example in this guide.

For the services described here, it is necessary to make port 80 (HTTP) and 443 (HTTPS) as well as 587 (SMTP Submission for incoming mails) externally available. After the setup, HTTP can be reduced to the encrypted port 443. For remote administration, especially for systems that are not in the home network, access to port 22 for SSH makes sense. Further ports may result from further applications, e.g., if IMAPS / SMTPS should be used for mail clients in addition to ActiveSync. While in home setup these ports are actively enabled in the local router, the configuration of a system operated by a provider should be designed to block all other ports.

In the majority of home networks, DCHP is used to assign IP addresses automatically. However, since the server address needs to be set in the configuration of the router for the release of the ports to external, the server must always get the same address. To achieve this, you can save the UCS system or MAC address in the router’s DHCP configuration. Alternatively, you can determine a fixed IP address during the UCS installation. In this case, however, it must be ensured that the router does not assign it to any other device. When using a fixed IP, please always ensure that the specifications for the default gateway and name server are correct. In the majority of cases, both is
the router’s IP.

How to setup Univention Corporate Server

For the installation, the UCS ISO image is downloaded from the official download link and burned onto a DVD or transferred to a USB stick. The system should then be booted from this medium (BIOS setting). The installation
begins and alongside a range of different steps such as the configuration of the language, the mounted hard disks are partitioned. In many cases, you can simply adopt the partitioning suggestion. If you want to increase the failure security with a software RAID or expanded partitioning, set it up manually. For details, please refer to the Debian documentation since UCS uses it's installation process here.

After the basic installation begins the actual UCS configuration.

The following information is practical for the planned setup.

  • Domain settings: As you are installing the first (and possibly only) system in a UCS environment, select “Create a new domain”. You are then prompted to enter a working e-mail address to which the subsequently required key will be sent.
  • PC settings: You will be asked for a F QDN for the UCS system. The first part of this is the name that will be given to the future system and its DNS domain. The basic configuration of many services in a UCS system are dependent on this setting. It is very difficult to change later on. In our example, we use the one of the FQDN "server.my-ucs.dnsalias.org". So the server feels responsible for the domain my-ucs.dnsalias.org. We are able to choose this procedure, as we assume in this example that all services of this domain are provided by UCS.
  • Software configuration: You can select the first services for installation here. For an internal network, install the "Active Directory-compatible Domain Controller" so as to be able to set up file shares in your network. For more details, refer previous guide Installation and configuration of UCS and the UCS official manual.

How to Access UCS

After the installation, you can access the system via an Internet browser at http://<IP> or http://<domain>. By clicking on the “system and domain settings” link, you get to the Univention Management Console (UMC) where you can log in as the “Administrator” using the password you specified during the installation process. The remainder of the setup is performed there.

Unlock the App Center

First thing you need to do after the installation and before you can install and set up the required services is to unlock the App Center. This is done via the "key", which is sent to the given address during the installation process. Upload the key directly from the welcome dialog that appears after the installation or go later to the UMC, click on the top right „Burger“ menu icon and select the point "License" and then "Import new license".

Configuration of the file sync & sharing solution ownCloud

The first app to be installed here is ownCloud, which is a common storage location for files from PCs and mobile devices. Open the "App Center" module in the UMC and search for "ownCloud". The installation of ownCloud can be triggered directly. Simply follow the instructions in the web interface.

After completing the installation, ownCloud can be reached via https://<ip>/ownCloud. This link can also be found on the overview page of the UCS server. When you go there, however, a warning message about the SSL certificate will appear first which we are going to eliminate later by installing Let's Encrypt.

Setting up Kopano mail & groupware

For the now following installation of a mail and groupware we are using Kopano. For our purposes you can use it for free. To setup Kopano mail and groupware, install "Kopano Core", "Kopano WebApp" and "Z-Push for Kopano" components from the App Center. During the installation of Kopano, a mail domain will also be created in UCS. Using the UMC module "Mail" from the category "Domain", you can ensure that the mail domain is configured correctly. In our example it is called "my-ucs.dnsalias.org".

After the installation, you can set up user accounts. The "primary mail address" is the mail address that the user will use in Kopano. It thus should use the public domain, for example name@my-ucs.dnsalias.org.

Fine-tuning of E-Mails

The mail service is now capable of receiving mails sent to the publicly accessible mail domain, here: my-ucs.dnsalias.org. To make sure that the sending of mails works without any problems and that mails will not be directly blocked by spam filters of other mail servers, this name should also be used as “helo”. For this, set the UCR variable “mail/smtp/helo/name” to the publicly accessible FQDN – in this example: my-ucs.dnsalias.org. The setting of UCR (“Univention Configuration Registry”) variables can be performed in the UMC module of the same name or in the command line with the command:

ucr set mail/smtp/helo/name=“my-ucs.dnsalias.org“

If possible, we also recommend to use an SMTP relay host. In particular if the sender’s IP address differs from that of the public domain. For more details, refer this guide.

Incoming mails are routed according to the current status of the implementation for the public DNS entry of the server: If mails are to be sent to addresses of the domain "my-ucs.dnsalias.org", the IP of the assigned MX record of the domain or the IP address of the domain itself is used in the DNS and contacted as the destination. The latter is the case in our configuration: the mail domain corresponds to the public name of the server, so that our system is found by other mail servers and contacted for the delivery of mails.

By default, Port 25 is specified in the UCS firewall. However, port 587 is preferred for the direct exchange between mail servers. This can be approved by UCR in the firewall. This can be done by setting the variable “security/packetfilter/package/manual/tcp/587/all” to “ACCEPT” – as above for the “helo” string, this is also possible here via the UMC module or the command line. Following the changes, the “postfix” and “univention-firewall” services need to be restarted. This can be done either from the command line (“service postfix restart; service univention-firewall restart”) or by rebooting the server.

Overview page of the Univention Portal

The overview page in UCS, the "Univention Portal", provides a good introduction to all available services. You can access it now easily via "https://my-ucs.dnsalias.org". However, there is still the certificate warning in the browser, which we've already seen during the ownCloud installation. It can be solved easily with Let's Encrypt.

Last but not least: Installation of Let‘s Encrypt

By default, the UCS web server uses a self-signed certificate, which leads to warnings in the browser. Via the installation of a certificate with “Let’s Encrypt” you can solve that. The corresponding app can be found in the App Center.

After installation, open a configuration mask by clicking on "App Settings": enter here the domains
(my-ucs.dnsalias.org and server.my-ucs.dnsalias.org), separated by spaces, and check-mark the services that should use the certificate. In our example the certificate should be used in Apache and Postfix. With a click on "Apply changes" a certificate will be created and integrated into the services. As the web server Apache is also restarted, you need to reload the web interface once, too.

Creation of users

Users can now be added to the system. For every user account created in UCS, a corresponding account is created automatically in ownCloud and, if a primary mail address has been specified, in Kopano, too. The user can then log in to both services with the account password. Password changes are possible via the menu in the Univention Portal.
Synchronization of Mails, Contacts and Appointments Kopano and ownCloud can also be used by smartphones. To synchronize e-mails, contacts and appointments with Kopano, an "Exchange" account is set up on the smartphone, for details see the Kopano documentation page.

ownCloud offers its own Android iOS app that allows you to share files with your smartphone and automatically save captured pictures and videos to the server.

Which other services can we recommend?

This setup is a good basis to integrate more services from the many apps offered for UCS:

  • In order to continue receiving from previous, existing e-mail addresses, the Fetchmail integration can be used. The UCS server will automatically download mails from other providers and provide them in the Kopano mailbox.
  • Publicly accessible servers are often targeted for automated attacks. If access to SSH in the firewall is allowed, this access should be limited. Refer this link for more details.
  • If the number of users increases, it can be useful to allow them to reset their password themselves. For this, install the "Self Service" app from the App Center.
  • ownCloud can be extended by many plugins. Especially helpful when dealing with many documents is the "Collabora" plugin, which allows you to edit office files directly in the browser.


If you have followed this comprehensive guide (and all the reference links) carefully, you have by now: successfully setup a private server with ownCloud, Kopano and Let's Encrypt on Univention Corporate Server. As you can see, setting up a home server on UCS is not that difficult. It is also worth mentioning that the UCS official manuals are extremely well documented and offers a very accurate and effective solution to all possible problems.

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