Author: Michiel

In this post I’m going to walk you through installing OTRS 4 on CentOS 7. The procedure will be very similar for Red Hat Enterprise Linux (RHEL) version 7 as this is binary compatible.

Please note that there are some differences between CentOS 6 and CentOS 7: it now ships with systemd and with firewalld so the instructions to install OTRS are pretty different.

Setting up your production server or migrating from one is something you don’t want to do every day. This means you better take a distribution that will receive security upgrades for a long time. This is why I would recommend CentOS version 7 over version 6 at this point in time.

Preparation: deactivation of SELinux

OTRS does not ship with a profile for SELinux. This means that you’ll have problems if you don’t turn it off. If you’re an advanced system administrator, you’d be able to create a profile for OTRS. This is beyond the scope of this post.

You can check the status of SELinux with the sestatus command:

[root@localhost ~]# sestatus
SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   permissive
Mode from config file:          permissive
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Max kernel policy version:      28

Edit the file /etc/selinux/config and set SELINUX=permissive.  This will make sure after a reboot selinux will not be enabled.

Type setenforce Permissive to set the current SELinux status to ‘permissive’. I chose Permissive here, rather than disabled, because otherwise you might loose the security context on files and would you want to enable SELinux on some later point you’d need to re-label files which is difficult.

[root@localhost ~]# setenforce Permissive
[root@localhost ~]# sestatus
SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   permissive
Mode from config file:          permissive
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Max kernel policy version:      28

Preparation: installation of a database

Of course you can use OTRS with a database that is on some central location in your setup. You can use OTRS with PostgreSQL or MySQL, or even with Oracle if you need to. In this example, I’m going to assume that you’ll use a database installed on the OTRS machine itself, which is the most common setup and recommended for all except very big installations.

The most widely used database for OTRS is MySQL. In CentOS 7, MySQL Server is no longer available; the fork MariaDB is available and you can use that as a drop-in replacement.

If you want to install MySQL instead of MariaDB, this is no problem; the MySQL project has provided a yum repository that you can use.

Otherwise, if you’d want to install MariaDB, just use these commands:

yum install -y mariadb-server
echo -e "[server]\nmax_allowed_packet=20M\nquery_cache_size=32M" > /etc/my.cnf.d/otrs.cnf
systemctl enable mariadb.service
systemctl start mariadb.service

The echo command is used to create a small configuration file called /etc/my.cnf.d/otrs.cnf which contains specific settings in order to make OTRS happy. The contents of this file is:

[server]
max_allowed_packet=20M
query_cache_size=32M

Get and install OTRS

Now you can get and install the OTRS software itself. You can find RPM installation files on the web server of OTRS. For the current version the install command is:

yum -y install http://ftp.otrs.org/pub/otrs/RPMS/rhel/7/otrs-4.0.2-01.noarch.rpm

Please note this will install loads of dependencies so it might take a brief while.

Install additional dependencies

Now you can install additional dependencies from EPEL, the enterprise quality package repository maintained by the Fedora project. Note that this step is kind of important as it also will bring you mod_perl which is really needed to have proper performance of the web server!

yum -y install epel-release
yum install -y mod_perl "perl(Crypt::Eksblowfish::Bcrypt)" "perl(JSON::XS)" "perl(GD::Text)" "perl(Encode::HanExtra)" "perl(GD::Graph)" "perl(Mail::IMAPClient)" "perl(PDF::API2)" "perl(Text::CSV_XS)" "perl(YAML::XS)"

Configure firewall and start Apache

Now you can start the Apache web server.  You should also add a rule to the firewall to allow access to the web server. CentOS 7 ships with firewalld, a new generation firewall that allows you to make these changes pretty easily.

You might want to remove the ‘welcome page’ of CentOS as it is kind of annoying.

rm /etc/httpd/conf.d/welcome.conf
systemctl enable httpd.service
systemctl start httpd.service
firewall-cmd --permanent --zone=public --add-service=http
firewall-cmd --reload

At this point you can continue using the Web Installer as explained in the OTRS documentation. As database you should choose ‘MySQL’ , also if you’re using MariaDB, because they really are forks and in this regard compatible. The database administrative password is empty. Note that this is not a security risk per se as the database only listens on localhost, so you can only access it from the local machine.

Of course there are many more tasks you should perform before considering your OTRS installation ready, but this is a nice quick start into setting up OTRS on a very popular, long-supported server OS.