Possible to stop ISPconfig access?

[mtleng]

I was hoping to be able to completely stop ISPConfig access in a manner similar to how the Webmin service can be stopped from the command line (/etc/init.d webmin stop). The goal is to have a quick command to completely disable access to the control panel until enabled again.

Can anybody think of an easy 1-liner command that would block ISPConfig from running?

PS. I noticed old posts referring to ispconfig_server under init.d but that doesn't appear to exist on my machine. I'm running an up-to-date Debian squeeze with NGINX+PHP-FPM.