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[mod] limiter: ip_limt - monitore suspicious IPs

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To intercept bots that get their IPs from a range of IPs, there is a
``SUSPICIOUS_IP_WINDOW``.  In this window the suspicious IPs are stored for a
longer time.  IPs stored in this sliding window have a maximum of
``SUSPICIOUS_IP_MAX`` accesses before they are blocked.  As soon as the IP makes
a request that is not suspicious, the sliding window for this IP is droped.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
This commit is contained in:
Markus Heiser 2023-05-27 21:36:34 +02:00
parent 9d7456fd6c
commit 52f1452c09
1 changed files with 27 additions and 1 deletions
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28
searx/botdetection/ip_limit.py
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@ -25,6 +25,13 @@ the request rates are reduced:
- :py:obj:`BURST_MAX` -> :py:obj:`BURST_MAX_SUSPICIOUS`
- :py:obj:`LONG_MAX` -> :py:obj:`LONG_MAX_SUSPICIOUS`
To intercept bots that get their IPs from a range of IPs, there is a
:py:obj:`SUSPICIOUS_IP_WINDOW`. In this window the suspicious IPs are stored
for a longer time. IPs stored in this sliding window have a maximum of
:py:obj:`SUSPICIOUS_IP_MAX` accesses before they are blocked. As soon as the IP
makes a request that is not suspicious, the sliding window for this IP is
droped.
.. _X-Forwarded-For:
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Forwarded-For
@ -37,7 +44,7 @@ from searx.tools import config
from searx import redisdb
from searx import logger
from searx.redislib import incr_sliding_window
from searx.redislib import incr_sliding_window, drop_counter
from . import link_token
@ -67,6 +74,12 @@ API_WONDOW = 3600
API_MAX = 4
"""Maximum requests from one IP in the :py:obj:`API_WONDOW`"""
SUSPICIOUS_IP_WINDOW = 3600 * 24
"""Time (sec) before sliding window for one suspicious IP expires."""
SUSPICIOUS_IP_MAX = 3
"""Maximum requests from one suspicious IP in the :py:obj:`SUSPICIOUS_IP_WINDOW`."""
def filter_request(request: flask.Request, cfg: config.Config) -> Optional[Tuple[int, str]]:
redis_client = redisdb.client()
@ -81,10 +94,18 @@ def filter_request(request: flask.Request, cfg: config.Config) -> Optional[Tuple
return 429, "BLOCK %s: API limit exceeded"
suspicious = False
suspicious_ip_counter = 'IP limit - SUSPICIOUS_IP_WINDOW:' + x_forwarded_for
if cfg['botdetection.ip_limit.link_token']:
suspicious = link_token.is_suspicious(request)
if suspicious:
# this IP is suspicious: count requests from this IP
c = incr_sliding_window(redis_client, suspicious_ip_counter, SUSPICIOUS_IP_WINDOW)
if c > SUSPICIOUS_IP_MAX:
return 429, f"bot detected, too many request from {x_forwarded_for} in SUSPICIOUS_IP_WINDOW"
c = incr_sliding_window(redis_client, 'IP limit - BURST_WINDOW:' + x_forwarded_for, BURST_WINDOW)
if c > BURST_MAX_SUSPICIOUS:
return 429, f"bot detected, too many request from {x_forwarded_for} in BURST_MAX_SUSPICIOUS"
@ -94,6 +115,11 @@ def filter_request(request: flask.Request, cfg: config.Config) -> Optional[Tuple
return 429, f"bot detected, too many request from {x_forwarded_for} in LONG_MAX_SUSPICIOUS"
else:
if cfg['botdetection.ip_limit.link_token']:
# this IP is no longer suspicious: release ip again / delete the counter of this IP
drop_counter(redis_client, suspicious_ip_counter)
c = incr_sliding_window(redis_client, 'IP limit - BURST_WINDOW:' + x_forwarded_for, BURST_WINDOW)
if c > BURST_MAX:
return 429, f"bot detected, too many request from {x_forwarded_for} in BURST_MAX"