A distributed denial of service (DDoS) attack can happen to anyone, at any time. If you have a website that’s running on a dedicated web server, it’s important to understand what a DDoS attack is, how to identify it, and what to do to stop and prevent it.
What
Is a DDoS Attack?
A distributed denial of service attack is when a hacker uses a botnet to send your web server an overwhelming number of HTTP requests in a very short period of time.
A
botnet is a very large network of computers across the internet that
are infected with a virus that transforms them into a relay for the
hacker’s software. Most computers on a botnet are regular computers
that have become infected by a virus, and the user doesn’t even
realize it.
During
normal operation, a web server provides your web page to visitors as
follows:
- A person types your URL into their web browser.
- The web browser issues an HTTP request to the website URL.
- Your ISP’s DNS servers converts the URL into the correct IP address of the web server.
- The HTTP request gets directed across the internet to the web server.
- The web server uses the page requested in the URL to find the correct HTML file.
- The web server responds with all of the content contained in that HTML file.
- The user’s browser receives the HTML file and displays the page to the user.
Most
web servers are sized with CPU and network hardware to handle the
average expected traffic per day. For some websites, that could be up
to a hundred thousand, or even a million visitors in one day.
However,
a hacker hoping to attack your website with a DDoS attack will
utilize a botnet of millions of computers from around the world, to
send thousands of HTTP requests per second to your web server.
Since your web server wasn’t sized for that volume of traffic, the web server will respond to your regular website visitors with the error message, Service Unavailable. This is also known as HTTP error 503.
In
rare cases where your site is running on a very small web server with
few available resources, the server itself will actually freeze or
crash.
How To Identify a DDoS Attack?
How
do you know if your website just went down because of a DDoS attack?
There are a few symptoms that are a dead giveaway.
Usually,
the HTTP Error 503 described above is a clear indication. However,
another sign of a DDoS attack is a very strong spike in bandwidth.
You can view this by logging into your account with your web host and opening Cpanel. Scroll down to the Logs section and select Bandwidth.
A
normal bandwidth chart for the last 24 hours should show a relatively
constant line, with the exception of a few small spikes.
However,
a recent disproportionate spike in bandwidth that remains high over
an hour or more is a clear indication that you’re facing a DDoS
attack against your web server.
If you believe you’ve identified a DDoS attack in progress, it’s important to act fast. These attacks consume a lot of network bandwidth and if you’ve paid for a hosting provider, that means their data server will experience the same spike in bandwidth. This can have an adverse impact on their other customers as well.
How To Stop a DDoS Attack
There is nothing you can do yourself if you’re facing a DDoS attack. But by calling your web hosting provider, they can immediately block all incoming HTTP requests headed toward your web server.
This
instantly relieves the demand on your web server, so that the server
itself won’t crash. It also prevents the attack from adversely
affecting the hosting provider’s other customers.
The
next step is to wait until the DDoS attack is over.
Such
an attack actually requires significant resources for hackers.
Usually, the attack is paid for by someone who wanted to shut your
website down. These payments are for an attack that last a specific
period of time, from an hour to several hours.
The
good news is that there will be an end to the attack. The bad news is
that by blocking all traffic to your web server until the attack is
over, the person who wanted to shut down your website essentially
won.
How To Beat a DDoS Attack
Unfortunately,
DDoS attacks are a simple and inexpensive way to shut down a website
for a short period of time.
The
attacks are never permanent, but they’re intended to send a
message. It means that something you’ve published on your website
upset someone enough that they were willing to pay hackers to attack
your site.
If
you run a critical online operation such as a large business, and
need your site to be resistant to DDoS attacks, it’s possible but
it isn’t cheap.
DDoS
protection services work by establishing a sort of counter botnet
that’s larger than the botnet running the DDoS attack. This creates
a distributed response to the incoming HTTP requests, even if there
are hundreds of thousands or millions of those requests.
There
are monthly service fees that come with those services. But if you
find yourself a frequent victim of DDoS attacks, these DDoS
protection services may very well be worth the cost.
DDoS
attacks can be at best a minor nuisance that causes you a few hours
of website downtime. At worst, it could cost you a significant amount
of lost online business, not to mention a drop in customers who trust
your website.
Understanding
how to identify a DDoS attack and how to stop it could reduce your
downtime, and reduce the time it takes for you and your hosting
provider to recover from it.