Distributed Denial Of Service (DDOS) is the intentional paralyzing of a computer network by flooding it with data sent simultaneously from many individual computers (so-called zombies) which are used to stage DDOS attacks

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What techniques do advanced firewalls use to protect againt DoS/DDoS?

It is hard to protect a server against Denial of Service attacks, DoS/DDoS. The two simple ways I can think of is to use a server with much resources (e.g. CPU and memory), and to build the server ...
94
votes
13answers
34k views

Why is it difficult to catch “Anonymous” or “Lulzsec” (groups)?

I'm not security literate, and if I was, I probably wouldn't be asking this question. As a regular tech news follower, I'm really surprised by the outrage of Anonymous (hacker group), but as a ...
31
votes
2answers
4k views

How can a Software application defend against DoS or DDoS?

Most of the solutions for DoS attacks are not at the application level. In case I am using a proxy server, what are the possible countermeasures for DoS at the application level?
25
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3answers
7k views

How do DoS/DDoS work?

In the last days one could frequently read about attacks from anonymous and LulzSec against different platforms like Sony or HBGary etc. Yesterday for example they DDoS'ed soca.gov.uk and jhw.gov.cn. ...
56
votes
5answers
42k views

How do major sites prevent DDoS? [duplicate]

As far as I know, I have never heard of or seen any large scale web sites like Amazon, Microsoft, Apple, Google, or Ebay ever suffer from DDoS. Have you? I have a personal philosophy that the bigger ...
37
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11answers
33k views

DDoS - Impossible to stop?

Is it possible - in theory - to stop1 a DDoS attack of any size? Many people claim it's impossible to stop DDoS attacks and tell me I just shouldn't mess with the wrong people on the internet. But ...
18
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2answers
6k views

Reject IP packets with an ICMP error, or just drop them?

Consider an internet-facing host (the outer firewall). What should be done with undesired traffic: just drop it, or send back an ICMP error such as port unreachable? (In Linux terms: iptables -P DROP ...
20
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5answers
22k views

How to simulate DDoS attacks from the Internet?

The idea behind security tests is easy. You want to know what a hacker can do - you hire a security expert who acts like a hacker to see how far he can get. You want to know what an evil admin can do ...
14
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3answers
4k views

Accessing a site (which is) under a DDoS

Lets say http://www.an-example-site.com is under DDoS attack. Alice, who does not have direct access to the hardware infrastructure, urgently wants some information which can be accessed through the ...
12
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5answers
7k views

What is a DoS Attack and how does it differ from a DDoS attack?

Can some one explain to me the concept of Dos Attacks for web applications ? Also what is the distinction between Dos and Distributed Dos ( ie DDos) attacks ? Wikipedia says : In computing, a ...
11
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7answers
4k views

How does CAPTCHA mitigate DDoS attacks?

This seems like an easy question, but I've failed to find an answer. One of the uses of CAPTCHA is to cope mitigate Denial of Service attacks. Suppose an adversary performs excessive login attempts, ...
7
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6answers
2k views

how to mitigate a DDoS from botnet on your website that comes from random IPs

I am wondering how do you mitigate a ddos attack which is coming from a botnet and hitting random URLs on a website. If there was a consistent URL it was hitting then it would be fairly simple, and ...
11
votes
2answers
2k views

How to test against DDoS in a controlled enviroment?

Can you suggest me methods or tools that can help in simulating a DDoS attack in a controlled enviroment (like my private lab)?
7
votes
3answers
12k views

How to protect myself against paid DDoS services?

I am domestic user and I am getting attacked regularly by a guy that hates me. Here is the background story: that guy uses Skype resolvers (tools offered by paid DDoS services) to find out my IP ...
1
vote
2answers
5k views

How much does it cost to protect your website against DDOS, by tier?

Cross-posted to Quora Today several financial institutes in Israel (banks, stock exchange) were DDOSed. They decided to block all foreign IPs as a first aid measure. While I agree that it was ...
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votes
1answer
169 views

How to avoid DDoS Attack [closed]

I buy my train ticket from our railway local web site. When ticket open for sale on web site then web site original traffic remain 50 (Just an example). Our railway web site is attacked by DDoS for ...
-1
votes
1answer
134 views

Slow internet - Worried about spammed packets

got a weird question and I'm not sure if I should even post this on here but I couldn't think of anywhere better to ask. Lately, I've been getting some internet speed issues. I closed literally every ...
18
votes
3answers
8k views

DNS Amplification DDOS attack

During the weekend I made some tests to simulate an DNS Amplification DDOS attack. sending about 90Mb/s traffic I was able to generate about x.x Gb/s amplified traffic which sent our datacenter ...
10
votes
1answer
2k views

Effects of DDoS attacks on memory use under Linux

Can someone whose Linux system is under DDoS attacks give me exact data on the effects of the Low Orbit Ion Cannon (LOIC), the High Orbit Ion Cannon (HOIC), Slowloris, PyLoris, Hping etc. on memory ...
13
votes
3answers
882 views

External websites in logs [duplicate]

I have a website, let's call it www.good.com. I've been getting a lot of requests to www.good.com under completely different URLs than www.good.com. I suspect this traffic is also causing some site ...
6
votes
2answers
4k views

Does a DDoS attack have other purposes beyond a lack of availability? [duplicate]

I'm currently researching DDoS attacks for an article I'm writing and apart from the obvious lack of availability of the target host and their services, is there anything else a DDoS can help ...
10
votes
4answers
8k views

Can someone launch a DOS attack on my IP

Suppose, I have a static IP on my PC and is known to others. None of my softwares listen for remote connection. Is it still possible for someone to DOS attack me in such cases? If yes, how it is ...
6
votes
3answers
1k views

Can the IPS technology in a UTM prevent a DDoS attack?

Does a Unified Threat Management appliance (UTM) with Intrusion Prevention (IPS) enabled have the ability to prevent a DDoS attack? I have read some articles and none of them have a perfect ...
0
votes
3answers
189 views

Why does an overload of requests give one root access all of a sudden?

There's this saying that using a DDOS-attack, people first attack a server using millions of concurrent requests and by doing that they miraculously gain access to the server. How does this work? Why ...
11
votes
4answers
8k views

Looking for botnet IP address feeds to protect against DDoS

I would like to get a live feed of botnet IP addresses delivered from a service and block them under certain conditions. Preferably community based/open source but open to looking at worthy commercial ...
8
votes
3answers
6k views

Block all BotNets and TOR addresses from accessing our site

I've heard that many DOS attacks and general "black hat hacking" attempts occur over the TOR network. Is it possible for me to dynamically block source IP's by their presence in a BotNet or similar ...
4
votes
2answers
1k views

How web application firewalls protect application from DDoS attacks?

How to protect a web application from DDoS by the implementation of Web Application firewalls? How effective is this method?
3
votes
1answer
581 views

Is it possible to force client use TCP instead UDP for DNS queries?

Assume I am managing a firewall between DNS server and clients. Is there any way to force clients use TCP rather than UDP, so we can prevent DNS spoof types of DDoS attacks?
3
votes
2answers
4k views

DDoS Protection for DNS providers

Zerigo, our DNS provider has reported to have been under heavy DDOS attack in the last 24 hours or so. Considering the distributed nature of DNS, and their architecture consisting of 5 main DNS ...
2
votes
0answers
229 views

Snort Parallelization Techniques and its effect on DDOS detection capability [closed]

I want to ask a query about snort parallelization. 1) Can snort detection rate remains same for all attacks after parallelisation? 2) As the parallelisation of netowrk traffic in each core is based ...
2
votes
3answers
4k views

DDoS on LAN: How to Defend?

DDos on a wired network has to be extremely rare, since the intruder has to be physically connected to the network. However, let's say that it still managed to happen. How would you be able to defend ...
0
votes
1answer
4k views

dns reflection attack vs dns amplification attack

Over the past few weeks I have heard discussions about a DNS reflection attack and a DNS amplification attack. Is there truly a difference between the two or are people just using 2 different names ...
0
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1answer
3k views

What is the difference between SYN cookie, SYN cache, and SYN proxy?

I am trying to understand some techniques regarding SYN flood prevention and there are three terms I couldn't find a clear explanation of. The terms that are confusing me are: SYN Proxy SYN Cache ...
11
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2answers
178 views

What is a Poison Dart attack?

From The Forrester Wave™: DDoS Services Providers, Q3 2015 report, (emphasis mine): Attack types defended CGI request, denial of capability, diluted low rate degrading, direct, DNS ...
4
votes
2answers
109 views

How do DoS attacks work on non-servers?

I understand how DoS/DDoS attacks work on servers. If I have not been misled, it is possible to DoS/DDoS a system that does not act as a server, but is still connected to the internet. How is this ...
3
votes
4answers
2k views

Spider Attack from several search engines at once

Hello my server is getting hit by spiders from bingbot, google, yahoo, yandex, and some place in the UK all at the same time crashing it. While I have no reason to think any one person did this, it ...
2
votes
3answers
1k views

Strange Apache access logs

A site of ours has been targeted by some kind of strange attack and I am trying to work out exactly how it has happening. Basically, the strangest thing is that the logs seem to correspond to entirely ...
0
votes
4answers
301 views

How can I remove an unknown device from my wifi network?

I have an OnHub (from Google), and there is a device I don't know on my wifi network. Is there some way for me to kick it, or DDoS it, whether through some command line command on windows or ubuntu, ...
0
votes
0answers
60 views

Are link-flooding attacks a real threat or only an academic scenario?

I read some papers about link-flooding attacks (i.e. flooding network links) and I wonder if these attacks are really of relevance in the real-world and what makes them so dangerous compared to ...
0
votes
4answers
404 views

What can a zombie computer feasibly install and run?

I'm experimenting with a Proof of Work system that tries to force the use of a browser in order to solve the client puzzle. Basically, instead of just handing off the puzzle as hash with a well known ...