DDoS stands for Distributed-Denial-of-Service. It basically means that a surge of information cuts you off from your network i.e. your server or your web host, disallowing access to web services. In recent times, a series of DDoS attacks have taken place, which is proven but the statistics put together by Arbor Networks’ 12th Annual Worldwide Infrastructure Security Report (WISR). The report indicates that incidences of DDoS attacks have risen 44% compared to last year. In fact, 53% of the service providers that were surveyed mentioned that 53 percent they are seeing more than 21 DDoS attacks per month, up from 44 percent last year. It is important to know if your network is under an attack, and take the necessary correction steps. Especially if you are an online business, a DDoS attack can wreak havoc, stopping your operations completely. An attack is initiated by sending a flood of traffic to your server or web host, thereby, eating into your available bandwidth and server resources. In effect, the original user, which is you, are left without access to web services. In extreme situations, the server may crash too. In fact, the attack is not launched from one source, making it difficult to track down a single IP in computer and data logs. The attacker generally infects user networks, including personal computers, mobiles, and IoT devices and so on, through his or her malware-infected machines. That is where the complexity of identifying a DDoS attack arises- it can quickly spiral into large proportions. Also, a DDoS attack can strike without warning, most hackers do not believe in sending threats before carrying out the hack. It may look like your website server or hosting domain is down, while in reality it may be a DDoS attack. Even elaborate server tests may just indicate a high traffic, which may appear normal. Hence it is important to be on the vigil and consider that you may indeed, be under a DDoS attack: Here are the key clues to look out for: An IP address makes x requests over y seconds, many times consistently, or IP addresses may repeat frequently: If you spot this behaviour for specific IPs, you can direct traffic from those IPs to specific NULL routes. This will bypass your servers. At the same time, make it a point to whitelist some of the valid IPs. Your server responds with a 503 error citing a service outage: Windows allows you to schedule alerts when a specific event happens in Event Viewer. Allocate a task to an event (such as errors or warnings). Similarly, allocate a task to a 503 event by opening Event Viewer, right clicking on the event, and set up a configuration to send an email to an administrator or to a team of people. Loggly can help you with this in case of multiple servers. Ping requests time out: Move beyond manually pinging servers to test response. A number of web pinging services are available, such as, UpTimeRobot, Pingdom, Mon.itor.us, InternetSeer, Uptrends and others. You can configure the frequency at which you want your site to ping from world-over. If a time out occurs, it is reported back to you or your team. Logs show a huge spike in traffic: Loggly can be used as a lookout for DDoS attacks. It not only shows traffic spikes but also their occurrence date and time, their originating servers and user errors. The logs and alerts can be designed to be more specific, for example, base your alerts on a combination of events and traffic spikes, so as to do away with false alerts. It is not practically possible for any human to keep looking out for these signs. One must automate notification systems. Loggly is a useful tool that can send these alerts to external messaging platforms too, such as Slack, or Hipchat. Of course, it is important that you learn how to perfectly configure an alert, to catch the right indicators, at the same time avoiding an overload of alerts. Source: http://www.readitquik.com/articles/networking-2/a-guide-to-identify-ddos-attack/

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How to Identify a DDoS Attack