asi:
out.println("user-agent: "+request.getHeader("user-agent"));
o bien para sacar mas informacion algo asi:
Código PHP:
<%
java.util.Enumeration names = request.getHeaderNames();
while (names.hasMoreElements()) {
String name = (String)names.nextElement();
out.println(name+": "+request.getHeader(name)+"<br><br>");
}
%>