Find the number of active sessions created from a given client IP address

Question

Is there a way to determine the number of active sessions created from a given client IP address?

Answer 1

The standard Servlet API does not offer this capability. The best you can do is save Map<HttpSession, String> yourself (where String is the IP address) and check each ServletRequest if HttpSession#isNew() and add it to Map along with ServletRequest#getRemoteAddr() . Then you can get the number of IPs with an active session using Collections#frequency() on Map#values() . You only need to make sure that you remove HttpSession from Map during HttpSessionListener#sessionDestroyed() .

This can all be done in one Listener that implements ServletContextListener , HttpSessionListener and ServletRequestListener .

Here is an example run:

 public class SessionCounter implements ServletContextListener, HttpSessionListener, ServletRequestListener { private static final String ATTRIBUTE_NAME = "com.example.SessionCounter"; private Map<HttpSession, String> sessions = new ConcurrentHashMap<HttpSession, String>(); @Override public void contextInitialized(ServletContextEvent event) { event.getServletContext().setAttribute(ATTRIBUTE_NAME, this); } @Override public void requestInitialized(ServletRequestEvent event) { HttpServletRequest request = (HttpServletRequest) event.getServletRequest(); HttpSession session = request.getSession(); if (session.isNew()) { sessions.put(session, request.getRemoteAddr()); } } @Override public void sessionDestroyed(HttpSessionEvent event) { sessions.remove(event.getSession()); } @Override public void sessionCreated(HttpSessionEvent event) { // NOOP. Useless since we can't obtain IP here. } @Override public void requestDestroyed(ServletRequestEvent event) { // NOOP. No logic needed. } @Override public void contextDestroyed(ServletContextEvent event) { // NOOP. No logic needed. Maybe some future cleanup? } public static SessionCounter getInstance(ServletContext context) { return (SessionCounter) context.getAttribute(ATTRIBUTE_NAME); } public int getCount(String remoteAddr) { return Collections.frequency(sessions.values(), remoteAddr); } } 

Define it in web.xml as follows:

 <listener> <listener-class>com.example.SessionCounter</listener-class> </listener> 

You can use it in any servlet, for example:

 SessionCounter counter = SessionCounter.getInstance(getServletContext()); int count = counter.getCount("127.0.0.1"); 

Answer 2

I needed to get this information quickly without new deployments. This can be done by modifying the JSP and adding the following snippet. (Only sessions with activity will receive a value):

 <% // Set user agent and ip in session session.setAttribute("agent", request.getHeader("user-agent") + "@" + request.getRemoteAddr()); %> 

Then create a groovy script to request jmx:

 import javax.management.remote.* import javax.management.* import groovy.jmx.builder.* // Setup JMX connection. def connection = new JmxBuilder().client(port: 4934, host: '192.168.10.6') connection.connect() // Get the MBeanServer. def mbeans = connection.MBeanServerConnection def mbean = new GroovyMBean(mbeans, 'Catalina:type=Manager,host=localhost,context=/') println "Active sessions: " + mbean['activeSessions'] def sessions = mbean.listSessionIds().tokenize(' '); def ips = [:]; def agents = [:]; sessions.each { def agentString = mbean.getSessionAttribute(it, "agent"); if(agentString != null) { agent = agentString.tokenize('@'); } else { agent = ['unknown', 'unknown']; } if(agents[agent[0]] == null) { agents[agent[0]] = []; } agents[agent[0]] += [it]; if(ips[agent[1]] == null) { ips[agent[1]] = []; } ips[agent[1]] += it; }; println "Ips" ips = ips.sort { -it.value.size } ips.each { ip, list -> println "${ip}\t${list.value.size}"; //println list; //println ""; } println "" println "Agents" agents = agents.sort { -it.value.size } agents.each { agent, list -> println "${agent}\t${agents[agent].size}"; //println list; //println ""; } 

Result

 Active sessions: 729 Ips unknown 102 68.180.230.118 11 80.213.88.107 11 157.55.39.127 9 81.191.247.166 2 ... Agents Mozilla/5.0 (compatible; MJ12bot/v1.4.5; http://www.majestic12.co.uk/bot.php?+) 117 unknown 102 Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm) 55 Mozilla/5.0 (compatible; Yahoo! Slurp; http://help.yahoo.com/help/us/ysearch/slurp) 29 ... 

Answer 3

A very good example of Balus C. We solved this problem using the Observer Listener. Here is a good example / tutorial for the same.

http://www.big-oh.net/BigOhSoftwareWeb/content/tutorials/requestObserverListener.jsp

Just thought it would be useful for other visitors. :)

Edit: *** April 2017 **

It appears that the http://www.big-oh.net/ site that contains the source above is dead. Here is a source from web.archive.org. Also the added file was linking to a web page in github gist. Gist source and html preview