for ip address

  public string IpAddress()
    {
        string strIpAddress;
        strIpAddress = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
        if (strIpAddress == null)
        {
            strIpAddress = Request.ServerVariables["REMOTE_ADDR"];
        }
        return strIpAddress;
    }

No idea about the MAC address but you can use Dns class of System.Net namespace to get the ip address and host name of the client (if allowed)

Sample code :-
IPHostEntry objEntry = Dns.GetHostEntry(Dns.GetHostName());
IPAddress[] arrAddress = objEntry .AddressList;
string host = objEntry .HostName.ToString();
string ip = arrAddress [2].ToString();

Don't forget to include the namespace.

Play with the object, i hope you'll find something for getting physical address as well