There are lots of ways to counter this. The simplest is a combination of session + cookie. Most people wont know how to / have any desire to delete the cookie.
IPs are useful, but be careful: - Some of the big ISPs (eg freeserve in the uk) have 'hidden' proxy servers, so if popular you may get more than one vote per hour from the same ip legitimately. - NAT - more that one person on a private NATed network may vote in close proximity! If you are really concerned with it, then put a limit on number of requests from an ip like you suggest. The most secure method i would suggest is to store each vote in the database with the ip. Converting the IP to an int will speed things up a lot! You can then implement a limiter and take a proactive blocking approach, or add an alerter, and take a reactive approach to mass votes! Daniel. -----Original Message----- From: Adam Hardy [mailto:[EMAIL PROTECTED] Sent: 13 April 2004 11:23 To: Struts Users Mailing List Subject: [slightly OT] defensive strategy Sorry for posting this OT question but I've got an issue that people on this list are very likely to have tackled: I am developing a traditional online survey app, the kind of thing that alot of people must have done. I am wondering how to protect it from script-kiddies who might want to see if they can bombard it with fake votes. It's basically public and anyone can take part in the surveys it will run. I put a switch to check for a flag in the session so that people don't vote more than once from the websites where the surveys will be deployed. But I am worried that kids writing scripts will not be stopped by session flags. Is it worth writing an algorithm to store the IP addresses used for the last hour? Or can they spoof IP addresses? If it is useful noting the IP addresses, how best should I store them? In a hashtable in application scope? In the database? In a session EJB? Thanks! -- struts 1.2 + tomcat 5.0.19 + java 1.4.2 Linux 2.4.20 Debian --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
