Install and Run Cockpit on Linux CentOS 7

[psnebc@localhost ~]$ sudo yum -y install epel-release
    [sudo] Passwort für psnebc: 
    psnebc ist nicht in der sudoers-Datei. Dieser Vorfall wird gemeldet.
    [psnebc@localhost ~]$ su -
    Passwort: 
    Letzte Anmeldung: Freitag, den 20. April 2018, 14:53:04 CEST auf tty1
    [root@localhost ~]# yum -y install epel-release     
    Loaded plugins: fastestmirror
    Loading mirror speeds from cached hostfile
     * base: centos.schlundtech.de
     * epel: ftp.nluug.nl
     * extras: ftp.uni-bayreuth.de
     * remi-php71: remi.mirror.ate.info
     * remi-php72: remi.mirror.ate.info
     * remi-safe: remi.mirror.ate.info
     * updates: ftp.fau.de
    Package epel-release-7-11.noarch already installed and latest version
    Nothing to do
    [root@localhost ~]# yum -y update
    Loaded plugins: fastestmirror
    Loading mirror speeds from cached hostfile
     * base: centos.schlundtech.de
     * epel: ftp.nluug.nl
     * extras: ftp.uni-bayreuth.de
     * remi-php71: remi.mirror.ate.info
     * remi-php72: remi.mirror.ate.info
     * remi-safe: remi.mirror.ate.info
     * updates: ftp.fau.de
    No packages marked for update
    [root@localhost ~]# yum -y install cockpit
    Loaded plugins: fastestmirror
    Loading mirror speeds from cached hostfile
     * base: centos.schlundtech.de
     * epel: ftp.nluug.nl
     * extras: ftp.uni-bayreuth.de
     * remi-php71: remi.mirror.ate.info
     * remi-php72: remi.mirror.ate.info
     * remi-safe: remi.mirror.ate.info
     * updates: ftp.fau.de
    Package cockpit-160-1.el7.centos.x86_64 already installed and latest version
    Nothing to do
    [root@localhost ~]# systemctl start cockpit
    [root@localhost ~]# systemctl enable cockpit.socket
    [root@localhost ~]# sudo firewall-cmd --add-service=cockpit
    Warning: ALREADY_ENABLED: 'cockpit' already in 'public'
    success
    [root@localhost ~]# sudo firewall-cmd --add-service=cockpit --permanent
    Warning: ALREADY_ENABLED: cockpit
    success
    [root@localhost ~]# firewall-cmd --reload
    success