Well, normally I'm not the person intended to do that, I'm a PHP developer and have general knowledge about Apache and security administration, but for emergency only I have to do this now.
I'm in a situation where I need to write Mod_Security rule that:
- blocks specific IP address from access our website,
- for 5 minutes
- if it try to call more than 10 links in less than 10 seconds
Can I achieve that writing a mod_security rule?
ModSecurity can do this, but wouldn't suggest it.
Have a look at the DOS rules in the OWASP CRS: https://github.com/SpiderLabs/owasp-modsecurity-crs/blob/master/experimental_rules/modsecurity_crs_11_dos_protection.conf. Note these do depend on set up in the main CRS setup file: https://github.com/SpiderLabs/owasp-modsecurity-crs/blob/master/modsecurity_crs_10_setup.conf.example
However ModSecurity collections are not the most stable especially for high volume. You run into problems with multiple threads accessing the collection file. Also might find you have to delete the collection file regularly (e.g. every 24 hours) to prevent it continually growing.
Related
I am modeling ticket system with various SLA. The model must contain several service blocks with different reaction time ( from 2 to 32 hours). In the service block only working hours should be taken into account. So in the service block timeout should stop when non-workong hours and on the weekend. Could you please kindly tell me how i can realize it?
Thank you very much in advance!
I can think of two answers, one simplified but works in many cases, the other more advanced and probably more accurate:
Simplified approach: I would set the model in hours and keep everything running as is without any stop. So, at the end of the simulation, if the total time is 100 hours and you know that you have 8 hours/day with 5 days/week, then you'd know the total duration is 2.5 weeks. Of course, this might have limitations or might become more complex later on if you want day-specific actions (e.g. you want to differentiate between Monday, Tuesday, etc.)
Advanced more accurate approach: Create resources whose capacities are defined by schedule and assigned them to your services. Create a schedule and specify the working hours in that schedule. Check the below link to learn more about schedules. I call this the more advanced approach because you need to make sure the schedule is defined correctly and make sure all elements in the model are properly controlled (e.g. non-service blocks such as source, delays, etc.).
https://help.anylogic.com/topic/com.anylogic.help/html/data/schedule.html?resultof=%22%73%63%68%65%64%75%6c%65%73%22%20%22%73%63%68%65%64%75%6c%22%20
I personally would use the first approach if the model is rather simple and modeling working hours is enough for analysis. Otherwise, I'd go for option 2.
Finally, another option I'd like to highlight is the "suspend/resume" functions. I am only adding this because you asked "how to stop timeout". So these functions specifically stop and resume timeout. But you'll need to define the times at which they are executed (through an event for example).
How to use drools in an environment where multiple users are working or accessing rules for the same operation.
Considering a drl which contains 5 rules and now these rules are being accessed by multiple users. This is obvious that rules will be stored in knowledgesession. Each time when a request happens system will do i/o and loads dt and drls then a new knowledgesession will be created.
We are going to have more than 1500 rules which will be managed in 150+ dts and 150+ drls.
A sample code lead will be appreciated.
The same knowledge session can be used by multiple requests as the the rules remain constant independent of the requests.I have created a KIE session when application loads which is independent of requests made.
Google Compute Engine allows for a daily export of a project's itemized bill to a storage bucket (.csv or .json). In the daily file I can see X-number of seconds of N1-Highmem-8 VM usage. Is there a mechanism for further identifying costs, such as per tag or instance group, when a project has many of the same resource type deployed for different functional operations?
As an example, Qty:10 N1-Highmem-8 VM's are deployed to a region in a project. In the daily bill they just display as X-seconds of N1-Highmem-8.
Functionally:
2 VM's might run a database 24x7
3 VM's might run batch analytics operation averaging 2-5 hrs each night
5 VM's might perform a batch operation which runs in sporadic 10 minute intervals through the day
final operation writes data to a specific GS Buckets, other operations read/write to different buckets.
How might costs be broken out across these four operations each day?
The Usage Logs do not provide 'per-tag' granularity at this time and it can be a little tricky to work with the usage logs but here is what I recommend.
To further break down the usage logs and get better information out of em, I'd recommend trying to work like this:
Your usage logs provide the following fields:
Report Date
MeasurementId
Quantity
Unit
Resource URI
ResourceId
Location
If you look at the MeasurementID, you can choose to filter by the type of image you want to verify. For example VmimageN1Standard_1 is used to represent an n1-standard-1 machine type.
You can then use the MeasurementID in combination with the Resource URI to find out what your usage is on a more granular (per instance) scale. For example, the Resource URI for my test machine would be:
https://www.googleapis.com/compute/v1/projects/MY_PROJECT/zones/ZONE/instances/boyan-test-instance
*Note: I've replaced the "MY_PROJECT" and "ZONE" here, so that's that would be specific to your output along with the name of the instance.
If you look at the end of the URI, you can clearly see which instance that is for. You could then use this to look for a specific instance you're checking.
If you are better skilled with Excel or other spreadsheet/analysis software, you may be able to do even better as this is just an idea on how you could use the logs. At that point it becomes somewhat a question of creativity. I am sure you could find good ways to work with the data you gain from an export.
9/2017 update.
It is now possible to add user defined labels, then track usage and billing by these labels for Compute and GCS.
Additionally, by enabling the billing export to Big Query, it is then possible to create custom views or hit Big Query in a tool more friendly to finance people such as Google Docs, Data Studio, or anything which can connect to Big Query. Here is a great example of labels across multiple projects to split costs into something friendlier to organizations, in this case a Data Studio report.
We are trying to implement a suite of spreadsheets that will handle budget figures for a set of stores. Everything works fine until we try to implement a spreadsheet that will collect data from all store spreadsheets and present statistics. Due to the limitation of ImportRange, of a maximum of 50 uses per spreadsheet doc, we have been implementing a Google docs script instead to handle the importing of data. But now when we have made a copy of the document to have one for each month, we are getting problems with our time triggers. We have setup a trigger to run the script once every minute and that results in an error message stating; Service invoked too many times: trigger.
What are the limitations here? And how do we best solve this?
We are also getting some other error messages and would like to know how to solve these;
Document tEHGO48zIBIFYRpb7Xhjwqg is missing (perhaps it was deleted?) (line 191)
Exceeded maximum execution time
Service error: Spreadsheets (line 290)
Where can we find documentation describing the different limitations and error messages?
Quota Limits for many services used with Google Apps Scripts have now been published on the Dashboard at:
https://docs.google.com/macros/dashboard
Just happened the same to me. It seems there is a non-published limit:
Premier accounts usually have larger quotas for every limitation.
The argument is that the account is better verified and less likely to exploit to resources.
But neither the regular limitations or Premier's better quotas are published by Google. And it seems that Googlers can't say it here in the forums either. The only well defined GAS limitation is the email quota, accessible through:
MailApp.getRemainingDailyQuota()
Which is 500 for regular accounts and 1500 for Premier.
Source: Google Support forums
Solutions are:
Join several scripts into one big trigger in case there is a limit in number of triggers
Optimize code (join loops, refresh only the necessary fields, etc.) in case it is based in CPU usage
Move minute timer triggers to OnEdit or OnOpen triggers whenever possible
Get a Premium Account
For your other errors, I haven't encountered any similar. You should post some details on the script or publish some code so we can debug it.
Windows Workflow Foundation has a problem that is slow when doing WF instances persistace.
I'm planning to do a project whose bussiness layer will be based on WF exposed WCF services. The project will have 20,000 new workflow instances created each month, each instance could take up to 2 months to finish.
What I was lead to belive that given WF slownes when doing peristance my given problem would be unattainable given performance reasons.
I have the following questions:
Is this true? Will my performance be crap with that load(given WF persitance speed limitations)
How can I solve the problem?
We currently have two possible solutions:
1. Each new buisiness process request(e.g. Give me a new drivers license) will be a new WF instance, and the number of persistance operations will be limited by forwarding all status request operations to saved state values in a separate database.
2. Have only a small amount of Workflow Instances up at any give time, without any persistance ofso ever(only in case of system crashes etc.), by breaking each workflow stap in to a separate worklof and that workflow handling each business process request instance in the system that is at that current step(e.g. I'm submitting my driver license reques form, which is step one... we have 100 cases of that, and my step one workflow will handle every case simultaneusly).
I'm very insterested in solution for that problem. If you want to discuss that problem pleas be free to mail me at nstjelja#gmail.com
The number of hydrated executing wokflows will be determined by environmental factors memory server through put etc. Persistence issue really only come into play if you are loading and unloading workflows all the time aka real(ish) time in that case workflow may not be the best solution.
In my current project we also use WF with persistence. We don't have quite the same volume (perhaps ~2000 instances/month), and they are usually not as long to complete (they are normally done within 5 minutes, in some cases a few days). We did decide to split up the main workflow in two parts, where the normal waiting state would be. I can't say that I have noticed any performance difference in the system due to this, but it did simplify it, since our system sometimes had problems matching incoming signals to the correct workflow instance (that was an issue in our code; not in WF).
I think that if I were to start a new project based on WF I would rather go for smaller workflows that are invoked in sequence, than to have big workflows handling the full process.
To be honest I am still investigating the performance characteristics of workflow foundation.
However if it helps, I have heard the WF team have made many performance improvements with the new release of WF 4.
Here are a couple of links that might help (if you havn't seem them already)
A Developer's Introduction to Windows Workflow Foundation (WF) in .NET 4 (discusses performance improvements)
Performance Characteristics of Windows Workflow Foundation (applies to WF 3.0)
WF on 3.5 had a performance problem. WF4 does not - 20000 WF instances per month is nothing. If you were talking per minute I'd be worried.