Server Fault Stack Exchange
Server Fault Stack Exchange

Questions tagged [denial-of-service]

Denial of service attack, is an attempt through some means to make a computer or network resource unavailable.

Some systems are susceptible to a simple "ping of death", where the amount of ping traffic is enough to disrupt their connectivity to the internet.

In more common scenarios, the amount of available upstream bandwidth becomes saturated by repeated requests for a file on the target computer, or by large UDP packets.
When the attack comes from more than one source IP, it is known as a distributed denial of service attack or DDOS

167 questions
0
votes
2 answers

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 Cloudflare to cache HTML as well, would a DoS attack be…
dodov
  • 141
  • 4
0
votes
0 answers

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 which the ip is assigned to is inactive/shutdown)…
Akhil Abraham
  • 1
  • 1
0
votes
0 answers

Investigating & Preventing DNS Service Crash

I am running a VPS on digital ocean droplet and facing DNS Service crashes since last three weeks. First time, it happened in late May, site wasn't resolving to IP and wasn't accessible. And same thing happened yesterday, and I wasn't aware of that…
Alena
  • 97
  • 1
  • 8
0
votes
1 answer

How can I prevent simultaneous connections from single IP?

I am running a Wordpress site on digital ocean droplet, and the droplet is running CentOS with CWP. Website is new so it has very low amount of genuine traffic, on average it has around 3-5 visitors per day. However, the site is under attack since…
Alena
  • 97
  • 1
  • 8
0
votes
0 answers

How to prevent DDoS taking place from my server?

I had originally asked this question on https://networkengineering.stackexchange.com/ but was redirected here. This is an informational question and I am not facing any DDoS attack of any sort. I was reading about DDoS attacks lately and there are…
ik005
  • 11
  • 1
-1
votes
1 answer

snort rule for rdp dos attack

i am very new in snort rules so i can't find the below rule exactly . is this rule send alert when tcp packets come from external network and any port to home network and port 3389? just check port , ip , protocol? if so , i think it can't detect…
sahar
  • 1
  • 1
  • 2
-1
votes
2 answers

Protect against DOS with iptables

Is there any way to protect against dos by analysing how much connection in a port have been done by an ip and not limit the traffic overall? For instance, let's say I don't want an ip to do more than 10 http requests per 10seconds, how I can do…
rsabir
  • 191
  • 1
  • 2
  • 10
-1
votes
1 answer

Possible DOS Attack or computer "freak out"

I am a dev-ops web developer with a site running two ec2.smalls behind a load balancer on AWS. Recently we saw 3-4 requests per second take down our clients site. The site was down and would not come back after multiple server reboots and errors…
zeros-and-ones
  • 315
  • 1
  • 3
  • 10
-1
votes
1 answer

How to duplicate a DoS attack

I've a WP blog who have received a DoS attack last days. server start using all CPU and memory, and eventually stop replying http request. It's a POST request to xmlrpc.php, I've checked the content of the $_POST var and is empty, so it looks…
Arnold Roa
  • 158
  • 10
-2
votes
2 answers

How does the DNS lookup query work?

Let's say, my domain's nameservers are registered like this: ns1.domain.com. ns2.domain.com. ns3.domain.com. The physical location for each of the server are as follows: ns1.domain.com. - in Tokyo ns2.domain.com. - in San Francisco ns3.domain.com.…
ikevin8me
  • 137
  • 1
  • 6
-2
votes
3 answers

Use two or more IP addresses to prevent DoS attacks

N00b question But say I had a dedicated server with two IP addresses, and the software (We'll just use Apache as an example) was using both IP address to serve content, in the event of a DoS attack on one of the IP addresses, could I just use…
Tom Gaben Newil Gibbs
  • 1
  • 1
-2
votes
1 answer

Apache: What is the best anti Denial of Service module and caching combination for a penny auction site?

The site is a simple penny auction site. The site runs on: MySQL PHP At any given time: an auction can have 100 - 2000 concurrent users. each user has one single "long poll" running in the background that keeps their display updated a user can…
rockstardev
  • 127
  • 3
  • 14
-2
votes
2 answers

Do some companies throttle servers at times of low use to save power?

I am attempting to index a large amount of data from a website and the last thing I want to do is DoS it accidentally. To prevent this, I was planning on doing it at night since it is not an international website. But if they throttle server…
luek baja
  • 99
  • 3
-3
votes
2 answers

How to stop a cmd/ping flooder

I banned a guy from my site for breaking rules and he mailed me saying he will cmd flood/ping the site until I unban him. He's been bringing the site down for three days now. My site is with a hosting company and they've not been that helpful, just…
effessess
  • 1
  • 1
-3
votes
1 answer

Acunetix surfaces a Slow HTTP vulnerability, how do I protect against slowloris?

How to protect from slowloris ? I have installed mod_antiloris and mod_qos and acunetix still warn about slowloris. mod_antiloris and mod_qos are loaded Apache/2.2.15 (CentOS) DAV/2 PHP/5.3.3 mod_qos/10.21 mod_antiloris/0.4 `Loaded Modules: …
Luka Tce
  • 37
  • 1
  • 2
  • 7
1 2 3
…
11
12