HOW TO RETRIEVE A VISITOR'S IP ADDRESS

How can I retrieve the IP address of visitors to my web app using MATLAB ?

for example in .NET, we can use:

public string IpAddress()

{ string strIpAddress; strIpAddress = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];

if (strIpAddress == null)

{ strIpAddress = Request.ServerVariables["REMOTE_ADDR"]; }

return strIpAddress; }

thank you