The Stack Overflow podcast is back! Listen to an interview with our new CEO.

Questions tagged [denial-of-service]

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

Filter by
Sorted by
Tagged with
0
votes
0answers
12 views

when install loic.sh install following error will be show [closed]

root@devesh[LOIC]#sh loic.sh install loic.sh: 34: loic.sh: [[: not found /usr/bin/git loic.sh: 59: loic.sh: [[: not found loic.sh: 55: loic.sh: [[: not found fatal: destination path 'LOIC' already ...
0
votes
0answers
30 views

Blocking DNS amplification attacks on ipv6 with iptables

I'm running a small Pi-Hole DNS server on my VPS, and I have the following iptables rules enabled to stop the DNS ANY amplification attack: *raw -A PREROUTING -p udp --dport 53 -m string --from 40 --...
0
votes
1answer
35 views

Cloudflare 525 error code and port scan

Today, Cloudflare return code 525 for some https connections. And I see many connections in iftop on the origin server. This connections - port scan. I used iptables, and block all packets, not from ...
1
vote
1answer
24 views

This IP was already used for a trial - spaming admin email

I use amazon lightsail and I get a lot of generated emails saying: "The IP .... was already used for a trial license on 2019-03-13" Where the IP changes to different IPs. The emails are from my cron ...
0
votes
0answers
22 views

Turning off network during Incoming DDOS

Sometimes on a server of mine, there is unsolicited incoming traffic (mix of random ports & random protocols beyond tcp/udp/icmp also) which starts peaking at 1 to 2 GBit/s while the outgoing ...
0
votes
0answers
54 views

How to block fake IP adresses?

on my webserver I find in the apache-logfiles: [Wed Jan 09 16:29:10.660069 2019] [:error] [pid 11705] [client 66.249.66.66:39066] script '/var/www/fairtragen/7327991037366506690.php' not found or ...
1
vote
1answer
240 views

Block requests in lighttpd made with HTTP/1.0 and only allow HTTP/1.1

I have a lighttpd web server that delivers PHP-generated webpages. This server is currently facing a lot of traffic due to a DDoS bot attack, and I am looking for a way to block or mitigate some of ...
-2
votes
2answers
395 views

What happens to your connection / modem when you are DDoSed and how can you prevent it? [closed]

I want to learn more about how DDoS and DoS attacks affect the network and how you can prevent them. I know how they 'work' and why the network is overloaded but I still dont know if a router / ...
0
votes
1answer
48 views

Being ddos-ed or my VPS has been compromised?

VPS bandwidth was suspended due to over usage. Didn't really promote my website at all cus it is still under development. Installed IFTOP and below is what I have captured. Any advice is greatly ...
0
votes
0answers
59 views

One machine on network switch seems to be killing network for others - Hacked?

I have been trying to setup a new headless Ubuntu server and I have been having all sorts of issues with crashes and server no longer being available. I initially thought that these were hardware ...
0
votes
2answers
55 views

Checking if a router is online or offline?

Recently I've been receiving ddos attacks to my router, for educational purposes, I want to know how the attacker is finding out when my router has been ddosed. They said they are doing something to ...
1
vote
0answers
55 views

Data security in server at home

I am a beginner linux user, and am planning on provisionally opening a game server on a machine I have at home. In addition to the possible DDoS attacks that may occur on this server (the server will ...
0
votes
1answer
510 views

Make Game Server DDoS-Protected

I'm a real noob in "server discussions". Im running game servers on Debian 8 but the datacenter doesn't provide physical firewall, So Im looking for a way to make my servers ddos protected, I did ...
1
vote
1answer
38 views

How to generate normal web traffic for DDoS Testbed to compute the false positive rate?

I'm implementing an algorithm to detect HTTP GET Flooding Attacks. I have used Bonesi as a bonet traffic generator to launch attack traffic. However, I need a real trace of a normal web traffic (or ...
2
votes
1answer
1k views

TP-Link DoS protection blocks Bonjour

We have an Apple-centric office and as such we rely on Bonjour (mDNS) for auto-discovery of things like printers, AirPlay targets, and pseudo-servers (e.g. exchanging files between desktop computers). ...
0
votes
0answers
46 views

Having too many ADPM and ICMP log in router admin panel

Recently, I feel that the speed of network became too slow. And I open router admin panel and have a look at the log messages. I found that there are many messages contains word "ADPM" and "ICMP", I ...
-3
votes
1answer
228 views

Designing a custom small DDoS detection and defense sytem [closed]

Am very new to the topic so I would like some guidance where to get started. What I want is, some tools to programmatically observe network traffic and preform some actions on the traffic. I don't ...
0
votes
2answers
2k views

Trying to understand anti TCP SYN flood attack IPTables rule

I’m currenlty working on a university assignment. I’m learning about firewalls and I need to configure IPTables on a Ubuntu machine to prevent a TCP SYN flood attack. I understand that this type of ...
0
votes
1answer
3k views

What happens if the router is ddosed?

I don't know what happens if a router gets DDOS'ed? Does it brick it self or it just disables its ip? And if the ip disables its just easy fix by power cycling the router to get a new ip and getting ...
-1
votes
1answer
66 views

Is there a way i can protect myself from DDOS attacks?

I got my IP spoofed somehow and how? Its because i visited a site which has a ip grabber and then a redirect to the site and my router is ADB and it has firewall but i don't think it won't help so i ...
2
votes
1answer
449 views

Am I under a DDoS attack?

OK, so here's some info: Fedora23 running in VirtualBox on a Windows 7 Host. Public-facing router has no DMZ, but port forwarding from 2325 (external) to 1194 (internal) and the internal static IP. ...
0
votes
1answer
2k views

Does Transmission Bittorrent client use UDP?

I am running a Transmission Bittorent server to upload various Linux ISOs. I am currently being flooded by UDP packets. I mean the DoS protection in the Archer C5 home router and it blocks parts of ...
1
vote
1answer
801 views

I can access websites through the web browser, but I can not ping them or interact in various other ways

as of around two weeks ago I've been having really weird interactions with the Internet that I can't explain, but please keep reading. I've tried looking for the issue myself and haven't found ...
0
votes
1answer
55 views

How can I bridge my router to my Linux OS?

I am getting ddosed a bit so I want to send all my router traffic to my Linux OS as a somewhat mitigation. How to send my router traffic to my machine?
1
vote
1answer
576 views

Implementing fail2ban the correct way

I have a Django web app where people write comments and upvote/downvote others' comments. The webserver is gunicorn + nginx (reverse proxy). The db is postgresql. The db and web app reside in two ...
0
votes
1answer
2k views

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 169....
0
votes
2answers
2k 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 ...
2
votes
1answer
135 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 ...
0
votes
1answer
610 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 ...
0
votes
2answers
64 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: ...
1
vote
1answer
205 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, ...
5
votes
3answers
12k 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?
8
votes
1answer
4k 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 ...
3
votes
1answer
1k 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 ...
0
votes
2answers
200 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 FTTC #...
9
votes
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 ...
0
votes
1answer
140 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 8,nop,nop,...
0
votes
1answer
1k 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 https:...
0
votes
0answers
381 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 ...
1
vote
0answers
30 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 (...
0
votes
1answer
493 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 ...
-2
votes
1answer
91 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 ...
0
votes
0answers
1k 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 ...
2
votes
0answers
499 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 ...
1
vote
0answers
101 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 ...
1
vote
0answers
684 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 ...
0
votes
1answer
226 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 ...
0
votes
1answer
1k 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 ...
1
vote
2answers
187 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 ...
1
vote
1answer
178 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 can ...