It is quite easy actually, i'm assuming you are using Windows OS ? In this case go to location of your hosts file, this usually is c:\windows\system32\drivers\etc\hosts. Now either open the hosts file with admin rights using notepad or any other text editor. You could also drag en drop the hosts file to your desktop and then open it with notepad or any other text editor.
Just add the following line:
localhost(lan ip) external host (wan ip)
examples:
192.168.1.4 myserver.serveftp.com
10.0.0.4 213.42.24.257
(you are now redirecting local traffic that is trying to connect to the wan ip/hostmask back to the localhost, eliminating the need for NAT loopback in your router)
Save the file and replace the hosts file with the edited one.
Do not forget to edfit the dZSbot config file, change
set bnc(LIST) "Site|ftptls://!checker: pass@localhost: port" into
set bnc(LIST) "Site|ftptls://!checker:
pass@your.wan.ip.or.hostmask: port"
Rehash the bot and your all set !