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
Re:Re: how to block the duplicated requests?
Understood. Really appreciate for your nice time. Thanks, At 2015-05-20 21:00:33, Christopher Schultz ch...@christopherschultz.net wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA256 On 5/20/15 4:22 AM, javalishixml wrote: More detail information as below: presudo-code step: This isn't pseudo-code. This is a re-statement of your problem. 1. a register page named http://mywebsite.com/register1.jsp; is set up, and this page contains a CAPTCHA image You didn't mention that CAPTCHA was already being used. Someone mentioned using it as a solution to your problem. What CAPTCHA are you using? Perhaps using a more effective one would help more than anything else. 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. No chance these are AOL users? Google for AOL ip address proxy. By the way, we get the IP from HttpServletRequest header. Where else would you get the remote IP address? 4. later, we setup a new register page. We change its url from http://mywebsite.com/register1.jsp; to http://mywebsite.com/register2.jsp; Are you trying to be evasive? Why have you moved your registration page? For the first several days, we find everything 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. So, back to my original question: How are you going to identify a duplicate request? Show some pseudo-code. 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. What about users behind proxies? Are you okay shutting them out? See the AOL anecdote above. 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? Are they preventing anyone else from using your site? Or are they just raising their numbers quickly enough that statistically, they always overwhelm your legitimate users and win the lottery? Is there a good way to resolve it at httpd level? Seriously, look-up mod_qos, mod_evasive, and mod_security and stop asking for solutions. We've already given you a whole bunch of ideas that consultants would have already bankrupted you for. Go do some work. - -chris -BEGIN PGP SIGNATURE- Version: GnuPG v2 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJVXIVxAAoJEBzwKT+lPKRY3AMQAIWrelhsrB9WnB8c+Wq7S2ia +L1dU+ZTI+VEeFBWy1ARUTtXM/viL7mE7QfofVVEjmMYAxrITrk9Nqn0DzmGBJAG JNcPkSHVAvhH9thOJDCfLvD69hV5sGCJdNC6RlYn235IEiai1IhH6ZQudrCXAPjl mMjZPX30W65MbA7fBMWG4NUJFi2BBz07zV8/teIwHQ/3w9fTs63o18alRwP5cGUk i1yu0lBf63xO5r7xnS5jN9fvklZe6FrCS+6RK2AAj2viF7mGi3kmaco1fdSQmTLY rdadMd0M9P6BgowMtBUAVNX4DnqJc2GIo8xlCySC/myvp8y3T9vwOvyRERoSW+8h a7oEPV6SKlFYKLHNg0XVgmkT3PHTjqojh2eOlKh8vO3W5YTw2R3xqXa4WUN0dHur cbD2RjSm7mA0Ewl+E2YsCbJAdfuPt3w77mIuv3FaV6ZPWdXLtSq0QARfGju0S11x bdEBaOzsQsm29qOC5MKMqG0tgHlY1Ya3BnGGxI+GTMat91d8kp92ufWeS5bmda3I BqOosM+GkgY9P1DATPXpR5A8Xi5Pp/lgkD4MYVNka2VH7FgKWckXlUhWoilDqFDX k4R9z/ZaRrDwqt6lwSAlRN4znwTw0OyP9FSLGr+VIKfKRUyweJss6pVUUGpxd3yQ ytK9Cbw2UpbOyFaiA1AE =CHtu -END PGP SIGNATURE- - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re:Re: how to block the duplicated requests?
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. 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: -BEGIN PGP SIGNED MESSAGE- Hash: SHA256 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 -BEGIN PGP SIGNATURE- Version: GnuPG v2 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJVWkTcAAoJEBzwKT+lPKRYnW0QAIeRbfJtsTKtUZHUig9sIRre y1mgJkPxBXjcRTfoZkZkTPhasYzINE1mb1mTPKfPbQveH+OmpawDREWJxg/6dFeg af734ZRpBOAs4MtlCyTXgBUWpWka5CcpeIRYeEwx5GKPFLJfTBbGpswV3HwLaoEC /NqMByVfwHnixBxSTGAM2GIOyrPf+Ii1Z0JpQyDEYcZUS3Dc3IFFeHPTvzQUb1SO NB84fwjDT6GG/YerrlRV3GHL3WYhAw1n+tQ9cCpSWDvz8/KLUyKXqVjX5s/FbuB+ S+krz2jzKqxG8bdeixW4s0i/9gyA/KcSSDgwmBnRwHsIUDvfF3pzk1Vq7rfGNpmQ L9V4brxL41H+ZMIDt2NjkVJb/UjgMnL5RpfQ1t+MdNvys/7UYav+vOv8jWqI3Mse AXNv46mQZAiMFzs/nsR7OIVLLxU70l+wbys4mK6u34uDip5gzxvVSaYKviqgKspx LT6MUHOpgmBhsiCUxjJ5odA4Q6mYhMfQxOB+6Ej8jRfKMT2uDTlwvU8gZ+/7TcUX JXngjQLQyjj+gAO+7jS7sWpaakV1ojy8/nFBVWH/3tWoo0YD89DJCRWxA8x8slfx oI9BGA0T7EwuX1CnqM90OLw7dymMQvwsTlkPAZnIvnWw3Xz29hIRazxQ7NR3AdCk vNXsseUzO18IJ4n+By1G =Q/ki -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
Re:Re: how to block the duplicated requests?
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 on these 2 items, we think the client is a robot. 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 alway find there is a same IP request our website the same url for many times, can I block this request at httpd level? Thanks, 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: -BEGIN PGP SIGNED MESSAGE- Hash: SHA256 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 -BEGIN PGP SIGNATURE- Version: GnuPG v2 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJVWkTcAAoJEBzwKT+lPKRYnW0QAIeRbfJtsTKtUZHUig9sIRre y1mgJkPxBXjcRTfoZkZkTPhasYzINE1mb1mTPKfPbQveH+OmpawDREWJxg/6dFeg af734ZRpBOAs4MtlCyTXgBUWpWka5CcpeIRYeEwx5GKPFLJfTBbGpswV3HwLaoEC /NqMByVfwHnixBxSTGAM2GIOyrPf+Ii1Z0JpQyDEYcZUS3Dc3IFFeHPTvzQUb1SO NB84fwjDT6GG/YerrlRV3GHL3WYhAw1n+tQ9cCpSWDvz8/KLUyKXqVjX5s/FbuB+ S+krz2jzKqxG8bdeixW4s0i/9gyA/KcSSDgwmBnRwHsIUDvfF3pzk1Vq7rfGNpmQ L9V4brxL41H+ZMIDt2NjkVJb/UjgMnL5RpfQ1t+MdNvys/7UYav+vOv8jWqI3Mse AXNv46mQZAiMFzs/nsR7OIVLLxU70l+wbys4mK6u34uDip5gzxvVSaYKviqgKspx
Re:Re: how to block the duplicated requests?
Hi On Tuesday 19/05/2015 at 20:10, 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 on these 2 items, we think the client is a robot. 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 alway find there is a same IP request our website the same url for many times, can I block this request at httpd level? Thanks, 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: -BEGIN PGP SIGNED MESSAGE- Hash: SHA256 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 -BEGIN PGP SIGNATURE- Version: GnuPG v2 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJVWkTcAAoJEBzwKT+lPKRYnW0QAIeRbfJtsTKtUZHUig9sIRre y1mgJkPxBXjcRTfoZkZkTPhasYzINE1mb1mTPKfPbQveH+OmpawDREWJxg/6dFeg af734ZRpBOAs4MtlCyTXgBUWpWka5CcpeIRYeEwx5GKPFLJfTBbGpswV3HwLaoEC /NqMByVfwHnixBxSTGAM2GIOyrPf+Ii1Z0JpQyDEYcZUS3Dc3IFFeHPTvzQUb1SO NB84fwjDT6GG/YerrlRV3GHL3WYhAw1n+tQ9cCpSWDvz8/KLUyKXqVjX5s/FbuB+ S+krz2jzKqxG8bdeixW4s0i/9gyA/KcSSDgwmBnRwHsIUDvfF3pzk1Vq7rfGNpmQ L9V4brxL41H+ZMIDt2NjkVJb/UjgMnL5RpfQ1t+MdNvys/7UYav+vOv8jWqI3Mse AXNv46mQZAiMFzs/nsR7OIVLLxU70l+wbys4mK6u34uDip5gzxvVSaYKviqgKspx
Re:Re: how to block the duplicated requests?
We find some client are always automatically fresh our lottery activity At 2015-05-18 23:56:51, David kerber dcker...@verizon.net wrote: How would you tell that a request is from a robot? On 5/18/2015 11:44 AM, javalishixml wrote: Hi, 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? Thanks in advance, Java Coder - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re:Re: how to block the duplicated requests?
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 Thanks, At 2015-05-19 04:00:28, Christopher Schultz ch...@christopherschultz.net wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA256 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 -BEGIN PGP SIGNATURE- Version: GnuPG v2 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJVWkTcAAoJEBzwKT+lPKRYnW0QAIeRbfJtsTKtUZHUig9sIRre y1mgJkPxBXjcRTfoZkZkTPhasYzINE1mb1mTPKfPbQveH+OmpawDREWJxg/6dFeg af734ZRpBOAs4MtlCyTXgBUWpWka5CcpeIRYeEwx5GKPFLJfTBbGpswV3HwLaoEC /NqMByVfwHnixBxSTGAM2GIOyrPf+Ii1Z0JpQyDEYcZUS3Dc3IFFeHPTvzQUb1SO NB84fwjDT6GG/YerrlRV3GHL3WYhAw1n+tQ9cCpSWDvz8/KLUyKXqVjX5s/FbuB+ S+krz2jzKqxG8bdeixW4s0i/9gyA/KcSSDgwmBnRwHsIUDvfF3pzk1Vq7rfGNpmQ L9V4brxL41H+ZMIDt2NjkVJb/UjgMnL5RpfQ1t+MdNvys/7UYav+vOv8jWqI3Mse AXNv46mQZAiMFzs/nsR7OIVLLxU70l+wbys4mK6u34uDip5gzxvVSaYKviqgKspx LT6MUHOpgmBhsiCUxjJ5odA4Q6mYhMfQxOB+6Ej8jRfKMT2uDTlwvU8gZ+/7TcUX JXngjQLQyjj+gAO+7jS7sWpaakV1ojy8/nFBVWH/3tWoo0YD89DJCRWxA8x8slfx oI9BGA0T7EwuX1CnqM90OLw7dymMQvwsTlkPAZnIvnWw3Xz29hIRazxQ7NR3AdCk vNXsseUzO18IJ4n+By1G =Q/ki -END PGP SIGNATURE- - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
