Anti-DDoS >


Hows does OVH counteract the DDoS attacks?




Managing DDoS attacks: Each step



The 4 stages of managing an attack:


1) The server is operational - no attack


Internet-based services are used without any problem. The traffic passes through the backbone of our network then arrives at the datacentre. Finally, it is handled by the server that sends back the responses over the internet.


InternetServerROUTERS
BACKBONE
ROUTERS
DATACENTRE


2) The DDoS attack begins


the attack is launched via the internet and on the backbone. Given the surplus capacity of the bandwidth on the backbone, the attack will not cause saturation on any link. The attack reaches the server, which begins to handle the initial attack. At the same time, analysis of the traffic flags up that an attack is underway and thus triggers the mitigation.


InternetServerROUTERS
BACKBONE
ROUTERS
DATACENTRE


3) Mitigation of the attack


Between 15 and 120 seconds after the attack has started, the mitigation is activated. The traffic coming in towards the server is vacuumed up by the 3 VACs, with a total mitigation capacity of 480 Gbps (3 x 160 Gbps), hosted in 3 OVH datacentres. The attack is blocked without duration or size limits, nor any other type of limit. Legitimate traffic passes through the VAC to finally reach the server. The server responds directly without passing through the VAC again. This process is called auto-mitigation.


InternetServerROUTERS
BACKBONE
ROUTERS
DATACENTRE


4) End of the attack


Generating an attack is costly, and even more so when it is ineffective. After a certain time has passed, the attack will come to an end. Auto-mitigation is maintained for 26 hrs after the attack has ended. This means any new attack that occurs within a few minutes, a few hours or 24 hours will be blocked. After just 26 hours, auto-mitigation is disabled but it remains ready to be reactivated on detection of a new attack.


InternetServerROUTERS
BACKBONE
ROUTERS
DATACENTRE