Re: Rate Limiting Apache: Units associated with "burst_rate_limit" ?

Hi Patrick



I’m doing exactly this for a small portion of a website which to prevent
aggressive scrapping of content. This config is working for me:



    <LocationMatch "^/protectedme$">

        SecAction "initcol:ip=%{REMOTE_ADDR},pass,nolog,id:100"

        SecAction "phase:5,deprecatevar:ip.hitcounter=1/5,pass,nolog,id:102"

        SecRule IP:HITCOUNTER "@gt 30"
"phase:2,pause:300,deny,status:429,skip:1,nolog,id:103"

        SecAction
"phase:2,pass,setvar:ip.hitcounter=+1,expirevar:ip.hitcounter=150,nolog,id:104"

    </LocationMatch>



This is a “leaky-bucket” type setup whereby you are allowed a burst of 30
requests and the rate reducses at 1 request every 5 seconds.


Kind regards,

*Jamie*
ib3 Limited
01732 449974


[image: logo]






--

*From:* Patrick Rynhart <[email protected]>
*Sent:* 11 March 2022 07:58
*To:* [email protected]
*Subject:* Re: [mod-security-users] Rate Limiting Apache: Units associated
with "burst_rate_limit" ?



Thanks for the reply, but I’m actually just wanting to protect a small
portion of the site.  Almost all of the site can and should run without
restrictions, except for some PHP scripts that (if hit repeatedly) cause
performance issues.



When I looked into mod_evasive, you didn’t seem to be able to nominate a
location or location(s) for which you could only apply limits to.



In other words, I want to wrap it into a Location – something along the
lines of the following:



<LocationMatch "^/some/URL/that/needs/rate/limiting.php.*">

  SecRule REQUEST_HEADERS:X-Forwarded-For "@unconditionalMatch"
"phase:2,initcol:ip=%{MATCHED_VAR},pass,nolog,id:100"

  SecRule IP:ACCESS_COUNT "@gt XX"
"phase:2,deny,status:429,setenv:RATELIMITED,skip:1,nolog,id:102"

…

</LocationMatch>



With that in mind – does anyone know how the “@gt XX” “burst rate” for
mod_security is calculated ?  In particular, how long before the burst
counter gets reset etc ?



Thanks,



Patrick



*From: *Brent Clark <[email protected]>
*Date: *Friday, 11 March 2022 at 8:42 PM
*To: *[email protected] <
[email protected]>
*Subject: *Re: [mod-security-users] Rate Limiting Apache: Units associated
with "burst_rate_limit" ?

Hiya

If you want to look to some type of rate limiting.?
Rather look to Apaches mod_evasive module.

Mod_evasive monitors incoming requests for suspicious activity from one IP,
such as:

    Several requests for the same page in one second.
    More than 50 simultaneous requests per second.
    Requests made while the IP is temporarily blacklisted.

The module sends a 403 error if any of these things happen.

HTH
Regards
Brent

On 2022/03/11 05:59, Patrick Rynhart wrote:

Hi all,



I’m wanting to introduce IP based rate limiting protection to our Apache
config, and am basing my config off this Gist:



https://gist.github.com/josnidhin/91d1ea9cd71fde386c27a9228476834e
<https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgist.github.com%2Fjosnidhin%2F91d1ea9cd71fde386c27a9228476834e&data=04%7C01%7CP.Rynhart%40massey.ac.nz%7C0fac6166573140a450ab08da0332b551%7C388728e1bbd0437898dcf8682e644300%7C1%7C0%7C637825813584279072%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=lu%2BO39925FXybkSHLv%2F2HTFdPpxrJwjJAxaQJMJI1nk%3D&reserved=0>



I’m wanting to understand the line:



SecRule IP:ACCESS_COUNT "@gt {{ burst_rate_limit }}"
"phase:2,pause:300,deny,status:503,setenv:RATELIMITED,skip:1,nolog,id:102"



In particular what are the units associated with burst_rate_limit ?  What
does it mean if you set this variable to a value like 100 ?  (Does this
correspond to a rate of 100 per minute ?  If not, what does it correspond
to ?)



Thanks,



Patrick







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