You can set IP addresses allowed to Login to your admin portal in Settings→Security Settings → Admin Area Allowed IPs.

If you'd like to go further, and block unwanted IP addresses on web-server level, you can do so by updating nginx config files.

How to IP-limit admin-area access on nginx

1. SSH to your HostBill Enterprise server as root:

# ssh root@yourhostbilladdress

2. Edit file:

/etc/nginx/locations/hostbill.conf

# nano /etc/nginx/locations/hostbill.conf

• Before section  location ~ \.php$ {  add:

• 
  
  

  location ^~ /admin { allow 1.2.3.4; allow 192.168.0.0/24; deny all; }

  
  

•  Make sure to change /admin to other folder name, if you have changed your admin folder 
• Add each allowed IP / CIDR subnet in new "allow X.X.X.X" block
• Save changes

3. Reload webserver's config

systemctl reload nginx