This post explains how to get IP address from PL/SQL.
O/P : 22.214.171.124, 126.96.36.199, 188.8.131.52
Function :- owa_util.get_cgi_env
This function returns the value of the specified CGI environment variable. Although the WRB is not operated through CGI, many WRB cartridges, including the PL/SQL Gateway, can make use of CGI environment variables.