Questions tagged [ddos]

A distributed denial of service attack (DDoS) occurs when multiple systems flood the bandwidth or resources of a targeted system, usually one or more web servers. These systems are compromised by attackers using a variety of methods.

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Have i been DDoSed? [closed]

I am a total newbie and i do not know if this is the place to ask this, but i have a problem: Today a person i know sent me a picture on Whatsapp via a bitly link. I opened it without thinking, and ...
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Verify ddos attack on my gcp vm instance

I am trying to test Google cloud security in comparison to other monitoring tools i need to simulate an attack on google cloud i tried installing low orbit on my ubuntu os and input the IP address of ...
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What happens when a post exceeds the limit of post_max_size?

If I send a payload of, for example, 10MB to an apache server, the limit being 2MB. How does the server know that the payload is 10MB? Doesn't he need to receive the file anyway, and check its size? ...
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Apache ProxyPass to NodeJS related to recent DoS Attack?

I was recently suspended for a DDoS attack from a testbed I have running on a VPS. The testbed has an apache server redirecting subdom traffic to a nodejs app listening on a localhost port. I use this ...
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Google CDN DDos Mitig

I am planning to use Google's CDN aka Cloud CDN. Does Cloud CDN include a minor mitigation against DDos attacks, like Cloudflare's free plan? Or do I have to create a security policy first via Cloud ...
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How to prevent DDOS attack impact on Netlify? (downtime + bandwith usage/cost)

Situation: React app that was initially running on a VPS A few days ago, we were the target of a DDOS attack that took the site down. During the attack, we decided to migrate to Netlify. Once ...
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62 views

I'm Under attacks even with mod_evasive mod_security and fail2ban [closed]

I have my centos fresh server with no problem, I have httpd, named but I get 150 failed logins per 10 minute. I also use Fail2Ban with maxretry 1 findtime 6h. and mod_evasive mod_security default ...
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Can CDN caching prevent DoS attacks?

Let's say I use Cloudflare to cache my images, CSS, and JS files. Requests for the HTML content itself still hit my server and an attacker could use that to his advantage. However, if I tell ...
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How to prevent a lot of strange requests

I have and https site, which for one week receives a lot of strange requests just to main web site page (+ 2 js and 1 css files, but no images). From nginx logs it looks like: 193.151.188.114 - - [02/...
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How to prevent simple ddos attack done apache benchmark (ab) command?

What would be the simplest way to prevent flooding with ab command ? ab -n 1000 -c 200 https://www.my-site.com I am totally conscious that this is just a partial prevention and there are thousands of ...
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UFW Weird ICMP log record - Pinging is blocked

In the log records below I have replace my eth MAC address with ETH_MAC_ADDRESS the IP of my server with MY_SERVER_IP and other IPs with STRANGE_IP plus a number to distingue. Jan 29 15:11:48 cld ...
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Extremely high incoming traffic on web server but no abnormalities in log files

Today we recorded extremely high incoming traffic (1 Gbps) on our Debian Webserver (green chart). On an average day it's at a maximum of about 20-30 Mbps. Firewall as well as fail2ban are configured ...
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iptables performance during high-pps UDP attack

One of my servers is under constant UDP DDOS attack. ~500Mb/s and 700k PPS. I have a 10Gbit downlink so that is not the bottleneck. In my IPTABLES I have created a 'whitelist' via ipset and dropping ...
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How much DDOS mitigation one should expect from VPS provider?

We had a stateful WebRTC application which received some DDOS attacks. The server had 2gbits port, so any attack over 2gbits was able to make it unavailable. Afterwards we refactored the application ...
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Can I report malicious ip addresses for money?

My servers get attacks from thousands of ip addresses everyday. I have an idea. Can I report those malicious ip addresses, or use the resource to earn some money? How? You may think these attacks are ...
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DDOS protection without IP?

Is there any way to do DDOS protection without logging IP addresses? Any way to stop attacks without noting down IP addesses? This is because of data protection regulations
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How to filter out the network timeout cause out of the output of tcpdump, wireshark and such tools?

third party Linux server sending around 15 GB of the data each day via FTP port 21 to my Linux (CentOS) server (headless). Problem is that recent days some of the transferred files timeout: ...
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Server is currently in DDOS attack, what can I do? [duplicate]

I'm running a game server using google cloud's instance. Apparently for the last 2 days, my server has been attacked I say so because when using nload, I get this result: ...
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Ddos Protection syntax - Nginx

I am using this syntax for my Nginx configuration file /etc/nginx/nginx.conf which reads: user www-data; worker_processes 2; pid /run/nginx.pid; worker_rlimit_nofile 100000; events { ...
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DOS Attack from local network to wan, identification and Prevention

Past few days, we have been facing a possible syn flooding DOS attack. This attack happens twice a day (afternoon and at night), one random IP in our network gets active (even though the system on ...
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How to stop requests on PHP server while it is running cron job sheduled PHP script?

I have a situation when some DDOS attacks are putting my PHP server down. Occasionally. I'm using AWS with auto scaling groups, so it is not a problem. The problems start when this server is going ...
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Meaning of Log File (DDOS) [duplicate]

We are currently facing attacks (probably DDOS) on our server. The incoming network traffic goes from an average of 20Mbps to 1Gbps in just 2-3 minutes. The lines in our log files usually look like: ...
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Are the mobility of the nodes lead to packet dropping in MANETs?

As we all know, lots of reasons can lead to normal packet dropping in MANET networks, e.g., unstable wireless channel, overloaded nodes, and so on. I have a question about whether the mobility of the ...
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Taking advantage of DDoS protection by tunneling traffic through a protected provider?

I'm looking to protect one public IPv4 address (let's call it Host A) that belongs to a dedicated server in a datacenter that has a somewhat lackluster DDoS protection. I have a high level theory ...
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109 views

How to secure a home server from a DoS attack? Questions about research [closed]

I have made research on several types of attacks, this page is a sample. Some attacks are not insanely harmful to overall system while most attack types are preventable by being careful or with the ...
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101 views

Hitch rate limiting without Varnish

Good morning, Is there a way to implement per-site and per-IP rate limiting on Hitch before the request reach Varnish? I tried to handle some DoS attack using Varnish rate limiting, but the DoS can ...
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111 views

Tons of Access from Google Proxy

I freaquently have a lots of access from google proxy. It says it is Google Favicon bot and I've checked it by host command. User-agent is like following. "Mozilla/5.0 (X11; Linux x86_64) ...
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Azure container instance receives tremendous traffic even right after its creation

I've created an Azure container instance with MSSQL container image. It starts. However before even login, or even putting the URL in to use, I've checked the container logs and it's being hit with ...
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81 views

Receiving a lot of NTP requests

On my server I see a lot of NTP requests. All NTP traffic is blocked by iptables. Is there anything more I could do to stop this traffic? 28M 1019M DROP udp -- * * 0.0.0.0/0 ...
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524 views

Prevent DDOS Attack on GCP App Engine

I've launched my application on GCP App Engine with 8 micro-services. I did an overload test with apache j-meter and it seems to scale well. However this can also be used as a DOS attack on my ...
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How to block / deny linux user from accessing a site with htaccess? [duplicate]

My site got hit ddos several times till now, i found that ddos traffic generally comes from linux os ... then, i wonder how to block linux users / traffic from accessing a site with htaccess?? Please ...
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Does cloudflare provide anti-DDoS protection for dedicated servers?

I have a dedicated server that sometimes gets DDoS attacked. Does Cloudflare give you protection for dedicated servers or is it for websites only?
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188 views

DDoS & Amazon Lightsail Load Balancing

One of the sites I host on Amazon Lightsail recently became victim of a DDoS attack. I've been able to fend it off using Cloudflare's "I'm under attack" mode. I'm wondering if load balancing ...
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248 views

Detect SYN flood attack in python

I have a piece of python code as follow s = socket.socket() s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) s.bind((IP, PORT)) s.listen(256) while True: revdata = "" try: ...
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103 views

iptables - synproxy target don't mark packets as INVALID

I am writing iptables rulles and have problem with preventing flood SYN. Found that synproxy should be the right solution. But when testing, I found that it don't mark packets as INVALID, so iptables ...
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59 views

How can do Load Test against WebSocket?

We will have to do a load test for the first time. To tell the truth, I don't know exactly what to look for and how to do it. I have also researched resources on this subject but I could not obtain ...
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45 views

nginx, http ddos protection crawled?

What is the best way to prevent crawlers from caching the "javascript verification" page? With Google there are no problems, but Bing does seem to cache it. All it takes - for the bot - is to reload ...
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209 views

Cisco ACL to block external DNS queries [RESOLVED]

One of the routers that I administer is getting bombarded with external DNS queries from the internet. This is a network border router which has a DNS server configured. There is an interface facing ...
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141 views

DDOS manual mitigation using command netstat. How to determine real attackers?

When my server is slow, I have been told to run this command and check if someone is making a request of SYN_RECV to slow down my server: netstat -npt | grep SYN_RECV | awk '{print $5}' | grep -Eo '(...
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55 views

How can I test the security of my server? I think I am under DoS

I got a server with Windows OS. The server is running many VMs using HYPER-V. The VMs are exposed to the internet. There is a single VM that is running NAT using windows RRAS, ehich is connected to ...
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957 views

Newbie Help! Windows Server 2012 R2 being hacked for DDos

I use a German server for RDP. Recently I received an email from my server provider that my server participated DDoS attack. It's so scary! Can anyone point a direction on how to resolve the issue? ...
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426 views

OVH server DDOS attack protection

I purchased the server on ovh.com. (not gaming, regular) For 3 days now I’ve been trying to set up protection against DDOS flood. Nothing comes out. Support responds once a day and does not give an ...
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158 views

Use ufw to block users from accessing my server via a specific vpn

The last couple of days I've been having some weird small DDoS attacks on different VPS's I have online. The first one I detected using netstat and I noticed a bunch of IPs that were from a ...
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Is this real google bot or attack? How do I deal with it?

So basically my site was unaccessible and I went to logs folder to see what's wrong and noticed a lot of weird requests from various IPs: 155.4.117.13 - - [30/Mar/2020:20:23:45 +0300] "GET / HTTP/1.0"...
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Apache too many child process - mpm_event caught SIGTERM shutting down

My Apache with ModSecurity, mod_evasive20 enabled occasionally geting crashed: These are glimpse of error log: [core:warn]**: child process 24709 still did not exit, sending a SIGTERM [core:error]**:...
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continuous hits my webserver with wordpress or Magento request but im not using either

I have a PHP website on AWS which is getting bad gateway so I have looked into Nginx server logs and found that an errors connect() to unix:/run/php-fpm/php-fpm.sock failed (11: Resource temporarily ...
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1answer
917 views

DigitalOcean Droplet and Managed Database with Load Balancer - DDOS Protection

I'll first start off by saying I'm no sysadmin or by any means knowledgable on servers, I'm just a developer tasked with a job of setting up the infrastructure for a SaaS application I'm working on, ...
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157 views

How to Hide real DNS server from OpenVPN?

OpenVPN show the DNS server in clear when you connect but i want to hide that from public. ( It shows that in logs and network adapter in Windows for example ) DNS server alreadly have rules to ...
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618 views

How do I limit ping (ICMP) responses on a debian 10 server?

I have a VPS with debian 10 installed, primarily used for website hosting. when I issue a ping to the server from a remote machine, I am able to and receive responses for packet sizes up to around ...
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My Site is under DDoS Attack [closed]

I hosted my website couponx.com in google cloud. For 24 hrs my site is under DDOS Attack. I have tried every way to get my site back. I spoke with Cloudflare as well. Still, the issue is not resolved. ...

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