A denial-of-service (DoS) attack is an attempt to deny service to legitimate users by sending extreme amounts of requests to a server.

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Invalid URI in request and apache stopps working

Today our apache stopped working, he did not crash but stopped to response. The only error i can see in the error_log is this: [Thu Feb 11 10:00:05.245233 2016] [core:error] [pid 7496] [client ...
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27 views

How virtual machines will be effected from DDoS attack on same physical server?

I mean let's suppose that there is a large DDoS attack to a virtual machine which is running on a physical server with other 10 virtual machines, how the other virtual machines will be effected from ...
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1answer
105 views

Firefox 43: Uploading to Youtube results in DoS behaviour

I've been trying to upload a video to my channel today, only to notice that Firefox starts using 100% CPU time on a single core and then suddenly, I and everyone in my household can't connect to the ...
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26 views

DOS attacks using cmd and protection against them

After finding someones ip you can easily send pings to them to make DOS attacks. Me and my friend tried to make a defense against them and wanted to know how a low level attacker can send this DOS ...
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2answers
54 views

Questions Regarding DoS

I have a few questions i still haven`t been able to get an answer to. If someone DoS you, do it affect all computers connected to the router or just the computer that is being attacked? For example: ...
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374 views

How does Cloudflare's DDOS protection work? [closed]

I am interested this purely because no matter how many times I read up on DDoS protection, I never really understand how it works. The nature of DDoS is that botnets will flood your server with HTTP ...
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1answer
47 views

Webserver accessible only from CloudFlare?

I wan't to avoid getting DDoSed as much as possible i can, so i thought if it's possible to set my web server to communicate only through CloudFlare. Any request from another source will be rejected, ...
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3answers
210 views

How ping a server which has ICMP blocked

I'm trying to ping a server which has ICMP blocked with normal ping. It's showing: Request timed out Is there any other method to ping it?
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57 views

How to get around a DDoS fully? [closed]

my network is currently down from a DDoS attack and I need to get around it. So far I found by switching to Googles DNS servers, I can access only some sites but not all of them. Is there another way ...
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1k views

What is a safe ping frequency without it being considered a DDoS attack?

I am trying to chart the uptime of a server by regularly pinging it and Google and then comparing the ping times. I want to keep doing this over a period of—let’s say—a week. I am sending a set of 5 ...
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1answer
179 views

My home IP (supposedly) was involved in a DDoS attack

There did not seem to be any SO community dedicated to computer security, so I'll ask here... As the title implies, my home IP (supposedly) was involved in a DDoS attack. I got a phone call from a ...
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172 views

Is it possible that I have caused a DoS to my son's tablets

I have three Internet connections at home, they are not connected to each other in any possible way, they are from three different ISPs FTTC #1 , the white modem and the black and white router ...
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71 views

Is this a DDoS attack?

I need some help identifying whether or not this is a DDoS or just a random network issue: Not really sure what to do...should I complain to my host? Change the IP?
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3answers
2k views

Will the maximum speed of a network card reduce the impact of an incoming DDoS attack?

I’m wondering if the maximum speed of a network card would reduce the chances of a DDoS affecting a home-hosted website. In this scenario, I’m hosting my website from an Android Tablet where the ...
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1answer
100 views

DDoS/botnet or what's going on, cloudflare.com?

This is small output from tcpdump -i re1 'port 25': 14:00:10.732034 IP cf-190-93-254-113.cloudflare.com.http > MY_IP.smtp: S 4234708404:4234708404(0) win 8192 <mss 1412,nop,wscale ...
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1answer
279 views

DDOS on port 443?

Recently my friend asked me whether his network is secure because he is setting up a game server on port XXX. I opened up Nmap on my linux machine and found port 443 opened. I tried to access ...
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0answers
225 views

Configure Router for better DDoS protection Actiontec MI424WR

So for the past month, my server has been attacked by script-kiddies three times. The server is mainly used as a minecraft server. I am getting worried that this is becoming an outbreak as many of ...
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29 views

How can I efficiently filter Dos packets? [duplicate]

I have recently been the victim of some Dos attacks. The facts : I received a very high amount of packets saturating my connection and preventing me from accessing the Internet during one hour ...
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1answer
320 views

Compromised Debian server sending DDOS attack

I have a server online that apparently has been compromised and it sends DDOS attacks to another ip. The system is a debian 7 server, hosting a few wordpress, joomla websites, and airtime to host a ...
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1answer
80 views

Protected from attacks through Skype

I know that people can find your IP through Skype and try to DDOS it and take your Internet down for a couple of minutes or hours. What I would like to know is: How many people need to DDOS you at ...
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0answers
750 views

Linux message: Possible SYN flooding on port 25. Sending cookies

I have a Linux CentOS server online. At my console this message appeared: possible possible SYN flooding on port 25. Sending cookies. See SYN flood and SYN cookies. I have done an Apache JMeter ...
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1answer
222 views

Block Google Docs from retrieving file on website - Stop Google DDOS [closed]

I was reading a very interesting article on how someone used Google Docs to preform a DDOS attack on a website. They basically filled a Google Docs Sheet with =image() requests to download a certain ...
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0answers
143 views

How to mitigate IP fragmentation attacks before reassembly when authentication information is available?

I'm trying to filter incoming traffic to high bandwidth, low latency network, to mitigate DDOS. The incoming traffic is custom UDP (I'm setting the protocol specs so I can force IP headers if ...
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56 views

A lot of random NAT tables appear

My brothers Mac seems to be infected. It keeps on sending UDP and SYN floods to our router, and it multiplies my ping 10 times.When I look in the NAT Mapping table there are a lot of random address ...
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194 views

Block packets by size in Windows

currently I am receiving an attack against one of my services running on Windows Server 2008 R2 with malicious UDP packets all of a specific length. I have tried dropping these packets with a plugin ...
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111 views

Can Torrent/DHT network remember my IP?

I suspect that my torrent activity casted some sort of "natural" DDOS attack on me. I had UPnP configured and each time I was starting uTorrent client, it was generating new random port and was ...
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571 views

Measure DDOS attack strength

I have been puzzled on this theory. Assume Server B is sending DDOS attack to Server A, so is it possible for a random client A, to be able to measure the attack strength, like the client A was able ...
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2answers
162 views

Can a home user behind a firewall be targetted by a DDoS attack?

I've read about an attack that targets simple home computer users who are playing online poker: Players A and B join a real money 1 on 1 tournament. You cannot unregister from this tournament and if ...
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1answer
154 views

Remove Windows 8 Nag (which executable to delete?) [duplicate]

I'm currently experiencing a Windows 8 DoS. When this nag ribbon is open, I cannot use the machine: I've tried closing the ribbon with ESC, ALT+F4, and a few others that used to close programs. I ...
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1k views

Is /root/b26 a DDoS process?

I have found this process: /root/b26 Here is a top: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 20810 root 20 0 339m 808 360 S 100 0.0 27:39.95 b26 I have ...
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3answers
97 views

Can I authenticate multiple times to one access point?

I'm attempting to test the security and stability of a new wireless access controller and assigned, it a has a /24 subnet of IP addresses to use for giving clients DHCP. I'm wondering if its possible ...
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2k views

DDoS attack on SMTP

I am not sure whether this is the right place to ask this. But now I am in a great difficult situation. Our server is undergoing SMTP DDoS attack. The mail service has been totally down. We have ...
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181 views

Why is preventing DDoS so hard? [closed]

I was thinking, if a DDoS attack can come in 2 ways: Sending large packets. Sending many packets. Why don't network administrators limit IP connections, to let's say 3 users/IP's and set a limit ...
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322 views

VPS hosting and DDoS attacks prevention

I'm curious if there is any way to create such a network so that if one machine is hosting a couple of VM's and one of the VM's gets attacked, it doesn't take down the network. Is there anyway to do ...
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166 views

If someone downloaded 600GB , can that be a DOS attack

Last night someone exploited some vulnerability in my site and then upload a PHP script to my images folder. I have an Amazon EC2 server with CentOS. Then the hacker downloaded 600GB and increased ...
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1answer
153 views

What this command :(){ :|: & };: does? [duplicate]

What does this shell command do in Linux :(){ :|: & };: How can it be used in Denial of Service attacks?
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3k views

Wireless router lods reporting loads of DoS attack attempts

We're having intermittent connectivity issues with our ADSL at the office. We've been dealing with our ISP for weeks and they don't know how to fix our problem. What happens is that at multiple times ...
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1answer
961 views

Was this a DDoS, a hack attempt, or something else?

I SSH’d into my home server earlier because it was taking strangely long to respond to HTTP requests. I noticed that the shell prompt was also acting slow. So I typed top, and saw several instances of ...
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1answer
1k views

Logging incoming IP addresses on a specific port

I've tried tcpflow and iptables but I'm unable to do so. I believe someone is attempting to DDOS my open port which is a server, so that my clients are unable to connect. From tcpflow I'm able to get ...
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144 views

Better configuring my firewall for Minecraft

Not long ago I purchased a new server, and I'm planning on running a Minecraft server on it. Now I'm trying to better configure my firewall to stop DDoS attacks on my server while running the ...
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1answer
363 views

DDOSED, Static IP but ISP says dynamic

I'm having a problem, sometime I'm getting ddosed for no reason (I verified with commview,wireshark). The first time I noticed I didn't think it was a problem because I was pretty sure my ip was ...
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1answer
265 views

How do I drop the entire INPUT chain from iptables?

On Linux, I've been building a malicious IP list. I assume the DDOS is now gone. How do I drop the entire INPUT chain from iptables, without affecting the FORWARD or OUTPUT chains?
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1answer
7k views

How to solve DDOS attacks in Windows Server 2008 R2 / Windows Server 2012? [closed]

Any software for windows Writing custom (intelligent) microsoft windows firewall extension (C#/C++/C) Writing custom (intelligent) firewall for windows Installing nginx etc. on the same computer and ...
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1answer
292 views

MacBook Air gets added to Watchguard XTM-21W Appliance's Blocked Site List?

We have this issue where one of our MacBook Air (Mountain Lion) users is periodically getting added to the Blocked Sites list within our Watchguard XTM-21 Appliance (XTM21-W). Couple of questions: ...
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2answers
342 views

Can an attacker create a DoS attack by sending TCP data segments?

I know about DoS by TCP SYN segments & want to know can it possile a DoS attack by TCP data segments?
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3answers
378 views

GoDaddy is attacked by Anonymous. Any way to bypass the DDoS to access email? [closed]

GoDaddy is attacked by Anonymous. Any way to bypass the DDoS to access email? We have all our email hosted and need access to it to operate.
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1answer
524 views

Route gameserver traffic through cloudflare? [closed]

I use cloudflare for my website and we have a gameserver I was wondering if it is possible to route traffic through cloudflare. This recently sprung into my head when I realized that I could route ...
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1answer
180 views

My server got a DDos attack; how can I debug further from logs? [closed]

My server got a 13 GBit DDoS attack so LeaseWeb nulled its IP address and the attack ended. My IP address is still blocked. I got a temporary second IP address, which is not yet public. How can I ...
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2answers
1k views

CSF/LFD - would I really need CPHulk enabled also?

So if I have the default configuration of CSF/LFD firewall running, should I enable CPHulk, or does CSF/LFD already do what CPHulk does? If the answer is "No, CSF/LFD does not do what CPHulk does", ...
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0answers
905 views

How to get rid of DOS attack: RST Scan?

I have Netgear Wnr1000v2 router. I have set my NAT to secure mode ( I don't know if that helps ). Many a times when I see my router's log I see lots of DOS attack: RST Scan. I somehow think that these ...