What you’ll Need :

1). A Linux server running with CentOS 7
2). SSH Root Access
3). Running domain which you want the point on Direct Admin for hostname for eg. server1.domain.com
4). Valid Client ID & Licence ID form Directadmin. 
5).  Install the following prerequisite packages: wget gcc gcc-c++ flex bison make bind bind-libs bind-utils openssl openssl-devel perl quota libaio libcom_err-devel libcurl-devel gd zlib-devel zip unzip libcap-devel cronie bzip2 cyrus-sasl-devel perl-ExtUtils-Embed autoconf automake libtool which patch mailx bzip2-devel lsof psmisc net-tools systemd-devel libdb-devel perl-DBI xfsprogs rsyslog logrotate crontabs -y

Let’s Start Step by Step DirectAdmin Installation on CentOS 7

Step 1). To install DirectAdmin firstly we need to disable the firewall. Login as a root to run the follow ing command :
setenforce 0
sed -i ‘s/enforcing/disabled/g’ /etc/selinux/config
Step 2). wget http://www.directadmin.com/setup.sh
Step 3). Change the downloaded setup file permission: chmod 755 setup.sh
Step 4). Run the command [root@centos ~]# ./setup.sh 

Step 5). The Installation wizard will be started to install DirectAdmin on your server. It will ask you if you want to install the prerequisite packages, answer yes

Would you like to install these required pre-install packages? (y/n): Y

Please enter your Client ID: Enter Client ID

Please enter your License ID: Enter your Licence ID

Enter your hostname (FQDN): server.domain.com

It must be a Fully Qualified Domain Name

Do *not* use a domain you plan on using for the hostname:
(don’t use domain.com. Use server.domain.com instead.)

Is this correct? (y,n) : Y

Is ens160 your network adaptor with the license IP (198.XXX.XXX.XXX)? (y,n) : y

Is this correct? (must match license) (y,n) : y

Would you like to search for the fastest download mirror? (y/n): y

Once the installation completed you will see the following output :

http://198.XXX.XXX.XXX:2222 (Use your own Server IP, not this one) and enter your Admin username and password when prompted.