The chances of being targeted by a DDoS attack are great and attempts are numerous.
A DDoS attack aims to render a server, service or an infrastructure unavailable by overloading the server's bandwidth or monopolizing its resources to the point of depletion.
During a DDoS attack, a multitude of requests are sent simultaneously from multiple points across the internet. The intensity of this "crossfire" renders the service unstable, or even worse, unavailable.
To protect your servers and services from attacks, OVH offers a mitigation solution based on VAC technology - an exclusive combination of techniques to:
There are three ways of making your site, server or infrastructure unavailable:
|Name of attack||OSI level||Type of attack||Explanation of attack principle|
|ICMP Echo Request Flood||L3||Resource||Also called Ping Flood, mass sending of packets including the response of the victim, which has the same content as the original packet.|
|IP Packet Fragment Attack||L3||Resource||Sending of IP packets that voluntarily reference other packets that will never be sent, which saturates the victims memory.|
|SMURF||L3||Bandwidth||ICMP broadcast attack usurping the source address to redirect multiple responses to the victim|
|IGMP Flood||L3||Resource||Mass sending of IGMP packets (multi-cast management protocol)|
|Ping of Death||L3||Exploit||Sending of ICMP packets which exploit an implementation bug in certain operating systems|
|TCP SYN Flood||L4||Resource||Mass sending of TCP connections requests|
|TCP Spoofed SYN Flood||L4||Resource||Mass sending of TCP connections requests to usurp the source address|
|TCP SYN ACK Reflection Flood||L4||Bandwidth||Mass sending of TCP connections requests to a large number of machines, usurping the victim's source address. The bandwidth of the victim will be saturated by the responses to these requests.|
|TCP ACK Flood||L4||Resource||Mass sending of TCP segment delivery receipts|
|TCP Fragmented Attack||L4||Resource||Sending of TCP segments that voluntarily reference other segments that will never be sent, which saturates the victim's memory|
|UDP Flood||L4||Bandwidth||Mass sending of UDP packets (not requiring a previously-established connection)|
|UDP Fragment Flood||L4||Resource||Sending of UDP datagrams that voluntarily reference other datagrams that will never be sent, which saturates the victim's memory|
|Distributed DNS Amplification Attack||L7||Bandwidth||Mass sending of DNS requests usurping the source address of the victim, to a large number of legitimate servers. As the response is more voluminous than the question, an amplification of the attack follows|
|DNS Flood||L7||Resource||Attack of a DNS server by mass sending of requests|
|HTTP(S) GET/POST Flood||L7||Resource||Attack of a web server by mass sending of requests|
|DDoS DNS||L7||Resource||Attack of a DNS server by mass sending of requests from a large set of machines which are under the attacker's control|