So this is more of a general question on the best practice of preventing DoS attacks, I'm just trying to get a grasp on how most people handle malicious requests from the same IP address which is the problem we are currently having.
I figure it's better to block the IP of a truly malicious IP as high up as possible as to prevent using more resources, especially when it comes to loading you application.
Thoughts?
How can DoS attacks be prevented?
For this, it is essential to have multi-level protection strategies that use intrusion prevention and threat management systems. These systems can use anti-spam, content filtering, VPN, firewalls, load balancing, and security layers to spot and block attacks before they overwhelm your network.
Which attacks can be stopped by blocking IP?
Enterprises can prevent the vast majority of DDoS attacks by blocking IP address spoofing and controlling inbound traffic. You only need to consider that more than 4.4 million distributed denial-of-service (DDoS) attacks occurred in the second half of 2021, to know with certainty that such attacks are always happening.
Can IPS block DDoS attack?
Almost every modern firewall and intrusion prevention system (IPS) claims some level of DDoS defense. Some Unified Threat Management (UTM) devices or next-generation firewalls (NGFWs) offer anti-DDoS services and can mitigate many DDoS attacks.
You can prevent DoS attacks from occuring in various ways.
- Limiting the number of queries/second
from a particular ip address. Once
the limit is reached, you can send a
redirect to a cached error page to
limit any further processing. You
might also be able to get these IP
address firewalled so that you don't
have to process their requests at
all. Limiting requests per IP address
wont work very well though if the
attacker forges the source IP address
in the packets they are sending.
- I'd also be trying to build some
smarts into your application to help
dealing with a DoS. Take Google maps
as an example. Each individual site
has to have it's own API key which I
believe is limited to 50,000 requests
per day. If your application worked
in a similar way, then you'd want to
validate this key very early on in
the request so that you don't use too
many resources for the request. Once
the 50,000 requests for that key are
used, you can send appropriate proxy
headers such that all future requests
(for the next hour for example) for
that key are handled by the reverse
proxy. It's not fool proof though. If
each request has a different url,
then the reverse proxy will have to
pass through the request to the
backend server. You would also run
into a problem if the DDOS used lots
of different API keys.
- Depending on the target audience for
your application, you might be able
to black list large IP ranges that
contribute significantly to the DDOS.
For example, if your web service is
for Australian's only, but you were
getting a lot of DDOS requests from
some networks in Korea, then you
could firewall the Korean networks.
If you want your service to be
accessible by anyone, then you're out
of luck on this one.
- Another approach to dealing with a DDOS is to
close up shop and wait it out. If
you've got your own IP address or IP
range then you, your hosting company
or the data centre can null route the
traffic so that it goes into a block
hole.
Referenced from here. There are other solutions too on same thread.
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