Hi What you explaining now and what you explained before are completely different story.
Simple and main cause for your issue is inefficiency and poor design. why don't you simply count number of users registering on particular ip and stop at threshold for certain amount of time. A simple request filter servlet would do the job. And maybe you might want to change the CAPTCHA, to a not_so_obvious_to_figure_out kind With regards Prabhu -----Original Message----- From: javalishixml [mailto:javalishi...@163.com] Sent: Wednesday, 20 May, 2015 4:22 PM To: Tomcat Users List Subject: Re:Re: how to block the duplicated requests? More detail information as below: presudo-code step: 1. a register page named "http://mywebsite.com/register1.jsp"; is set up, and this page contains a CAPTCHA image 2. the robot(crackers) could successfully register the thousands different users for this web site during only several minutes. 3. if it is a human beings, these thousands different users should have different IPs. But we find these thousands different users are from same IPs. By the way, we get the IP from HttpServletRequest header. 4. later, we setup a new register page. We change its url from "http://mywebsite.com/register1.jsp"; to "http://mywebsite.com/register2.jsp"; For the first several days, we find everthing is good. But after several days, we find the robot(crackers) find this new URL and could successfully register the thousands different users for this web site during only several minutes. It's just reproduced steps for our issue. Our requirements are that: 1. we have a URL for register page. we don't want the thousands different users with same IP could successfully registered during a very short time window. 2. We can have a policy to set an interval time window. Based on this interval time window, the same IP should NOT register users again and again. 3. This policy should manage a group of URLs. We can always add the different URLs for this policy. Because based on our maintaining activities, we may set up many different register page again and again. Is it a DDOS attack? Is there a good way to resolve it at httpd level? At 2015-05-19 21:16:29, "Christopher Schultz" <ch...@christopherschultz.net> wrote: >-----BEGIN PGP SIGNED MESSAGE----- >Hash: SHA256 > >To whom it may concern, > >On 5/19/15 8:09 AM, javalishixml wrote: >> Just understood you. Really appreciate for your feedback. >> >> >> How do we judge it's a robot? item1: we find the request IP is >> always the same one. item2: our page may contains several >> keep-alive connections. But the attack connection only focus on >> connection. > >Based upon the first request, how can you tell that the robot is going >to make later keep-alive requests? > >> Based on these 2 items, we think the client is a robot. > >Can you write some pseudo-code that shows the algorithm in its >simplest form? > >> I think maybe putting these 2 items together to consider it as a >> robot is a bit complex. Let's do it from the simple point. >> >> If we always find there is a same IP request our website the same >> url for many times, can I block this request at httpd level? > >This sounds like a job for mod_qos, mod_evasive, or mod_security. > >- -chris > >> At 2015-05-19 20:01:00, "David kerber" <dcker...@verizon.net> >> wrote: >>> On 5/19/2015 7:53 AM, javalishixml wrote: >>>> >>>> >>>> >>>>> I doubt you're going to be able to do this in httpd, unless >>>>> you have a very simple, straight forward way of identifying >>>>> the robots. >>>> Yes. I just want to have a way to block the duplicated requests >>>> at httpd level. After all, my website has to face the the big >>>> concurrency issue. >>> >>> I understand that's what you want. What we're telling you is >>> that you probably won't be able to do that. >>> >>> Let me ask the question again, that Chris asked before: how do >>> you tell that a given request is from a robot? >>> >>> The answer to that question will determine if you can block it >>> with httpd. >>> >>>> >>>> >>>> >>>> >>>> >>>> At 2015-05-19 19:35:26, "David kerber" <dcker...@verizon.net> >>>> wrote: >>>>> On 5/19/2015 1:03 AM, javalishixml wrote: >>>>>> Thanks a lot for your information. >>>>>> >>>>>> >>>>>> This solution is based on tomcat level. If I always handle >>>>>> this issue at java level, I'm afraid it has performance >>>>>> issue. Because this web site afford a very big concurrency >>>>>> access. >>>>>> >>>>>> >>>>>> Taking a consideration on its basic architect >>>>>> tomcat+apache, I think the best way to move this solution >>>>>> from tomcat to apache. So do you have some good solution at >>>>>> apache's configuration? I understand this is a mail list >>>>>> for tomcat.. but just want to get any information >>>>> >>>>> I doubt you're going to be able to do this in httpd, unless >>>>> you have a very simple, straight forward way of identifying >>>>> the robots. >>>>> >>>>> >>>>> >>>>>> >>>>>> >>>>>> Thanks, >>>>>> >>>>>> >>>>>> At 2015-05-19 04:00:28, "Christopher Schultz" >>>>>> <ch...@christopherschultz.net> wrote: >> To whom it may concern, >> >> On 5/18/15 11:44 AM, javalishixml wrote: >>>>>>>>> I have a website. It is built by apache + tomcat. >>>>>>>>> >>>>>>>>> Now we make a lottery activity at this website. But >>>>>>>>> we find that some robots always raise the duplicated >>>>>>>>> requests to hit this lottery activity. It causes that >>>>>>>>> robots almost get all the awards. >>>>>>>>> >>>>>>>>> So we just want to block these kind of duplicated >>>>>>>>> requests at every interval unit. For example, we set >>>>>>>>> the interval unit is 3 seconds. The if the robot want >>>>>>>>> to hit the lottery activity in 3 seconds, the website >>>>>>>>> could block this action. >>>>>>>>> >>>>>>>>> So how to do it? I suppose if we do it at tomcat >>>>>>>>> level, is it a very low performance? Can I do it at >>>>>>>>> apache level? how to do it? If I could not do it >>>>>>>>> apache level, can I do it by setting sth at tomcat? >> >> If you have a way to identify a "duplicate" request (e.g. using a >> fingerprint of the request that you can check during that 3-second >> interval), then this is conceptually very easy. >> >> It may not be great for performance, but you'll have to weigh that >> against your own requirements. (For example, which is worse: poor >> performance, or a site where only robots ever win the lottery?) >> >> This will not be something you can configure in Apache httpd or >> Tomcat. This will have to be an application thing (unless you can >> describe the fingerprint technique to some httpd module such as >> mod_security or mod_qos and then allow it to discard duplicates). >> >> Back to the solution: >> >> 1. Take a fingerprint of the request 2. Lookup the fingerprint in a >> database of previous requests ( fingerprint -> latest timestamp ) >> 3. If the fingerprint appears in your database and the timestamp >> is less than 3 seconds ago, discard the request 4. Otherwise, store >> the current timestamp and fingerprint in the databas e >> >> For a database, I might recommend something like memcached or >> another in-memory-style database. An in-memory key-value store is >> really what you are looking for. Memcached has a nice feature where >> values can automatically time-out (e.g. they are invalid after 3 >> seconds), so you can make your application code a bit simpler >> because you'll never have a value in the database that is not >> valid. >> >> Hope that helps, -chris >>>>>>> >>>>>>> ----------------------------------------------------------------- >- ---- >>>>>>> >>>>>>> >To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >>>>>>> For additional commands, e-mail: >>>>>>> users-h...@tomcat.apache.org >>>>>>> >>>>>> >>>>> >>>>> >>>>> ------------------------------------------------------------------- >- -- >>>>> >>>>> >To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >>>>> For additional commands, e-mail: >>>>> users-h...@tomcat.apache.org >>>>> >>>> >>> >>> >>> --------------------------------------------------------------------- >>> >>> >To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >>> For additional commands, e-mail: users-h...@tomcat.apache.org >>> >-----BEGIN PGP SIGNATURE----- >Version: GnuPG v2 >Comment: GPGTools - http://gpgtools.org > >iQIcBAEBCAAGBQJVWzetAAoJEBzwKT+lPKRYh1sP+wQYPO7BY9Stg2XdvzK9GDA0 >/cqRMxIZ2Thq84GzHRKcg2pyC2iN3M+LMCxXCodKdp6+Cl0DfU6H0ijKucy4yHET >FrwhHT/7A1A7bQ4eT6IYhu1R7dtLhM0o5YRwYDDClKSfvsACTmuLOEmin40bmTeH >uuREu7EDz1fdNgOpjpDBNw1bC4ZkyYMlhQZ3Ox/jopnxKqRCXcjUx+kZH1UktJu9 >NBBs7rQgvSXFpNtB2DPFBS6pgy97jNSgKgWqoqX0WaQwQkfU1dLIyrH6I2v4/22s >ldCE7sZDQrRR6PUAyMQVVj36H5WHH+xlxr0zSrkdxvy5bFFqjNoCb8fRh3+J8sGC >yd0hesq3QW+uSwkwJOg4LsDkGFHCTYNiZZMLBRULGBabFbnHCXKIRjie3h0JGSfb >uL8diC2sNydKH7Re8WifQ8wqPvqIqkN+oakHed+oLg6BhToJvZJY2mTYuJRdb6gc >iRYRZ1+dH78PrgwLgovRDQHrnNVQRfUTpEyQOfygBi46o5Hh1t1fIADDMMtQ+yLX >C/Fg7JO5+vN2AoG3A1UOHUmoTGi7bAOlqp4RUwJXdN9pho++ullP8X8SfAfW52VZ >A5mZIb3FuI2GstOAcZPIzg63m1dr69d4CY3QCQdYUu5GnmlR9ws/LHwrI0Hbl4DH >FiXD3fsPSgRYvjCXPISV >=PWnL >-----END PGP SIGNATURE----- > >--------------------------------------------------------------------- >To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org >For additional commands, e-mail: users-h...@tomcat.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
