Moving domain between user accounts can be done with following command,

cd /usr/local/directadmin/scripts
./move_domain.sh domain olduser newuser

Here,
domain = the domain name you want to move
olduser = current user
newuser = new user of the domain

To enable browsing websites with IP address, you have to run following commands

cd /usr/local/directadmin/custombuild
./build set userdir_access yes
./build rewrite_confs

The website can be visited with IP address. For example, 194.245.58.124/~username
This will enable browsing default website of the username.

And to disable website with IP address:

cd /usr/local/directadmin/custombuild
./build set userdir_access no
./build rewrite_confs

https://www.transip.eu/knowledgebase/entry/653-directadmin-tutorial-series-securing-your/

• Change SSH port.
• Restrict access to DirectAdmin to specific IPs.
• Brute force protection in the form of Fail2Ban and a configuration adjustment in DirectAdmin.
• Anti-virus/malware protection with ClamAV.
• Optional: Restrict access on ‘Admin Level’ to specific IPs.

Change SSH port

1. Check your used ports

   netstat -tulpn | less

2. Choose a random port number between 0 and 65535 that is not shown in the overview (for example 56316) and press ‘q‘ to stop netstat.
3. Open the SSH configuration file

   nano /etc/ssh/sshd_config

4. Configuration file will open and search for #Port 22 and replace it with Port 5 (remove # and put your desired port number)
5. Save the file and close it CTRL+x > y
6. Add the chosen port to your firewall

   firewall-cmd --permanent --zone=public --add-port=56316/tcp

8. Your SSH port has been changed