Authentication template variables for ip address

With reference to below doc 

https://docs.sophos.com/nsg/sophos-firewall/20.0/help/en-us/webhelp/onlinehelp/AdministratorHelp/WebServer/AuthenticationTemplates/index.html

Is there any variable available to get client ip address?

Example "client_ip" ?

I wish to embed some javascript for which client ip is required for decision making for my internal application.

I doubt cross domain ajax whether works or not in sophos captive portal.