DDoS Attacks Explained: Types, Impact and How to Defend
A distributed denial-of-service (DDoS) attack floods a target with traffic from many sources until legitimate users can no longer get through. Attacks are cheap to launch, and their size and frequency continue to grow. For ISPs, banks, e-commerce and government services, availability is now a security issue.
Three main types
- Volumetric: saturate bandwidth using amplification (DNS, NTP, memcached and similar reflectors).
- Protocol: exhaust state tables in firewalls and load balancers, for example with SYN floods.
- Application-layer: send seemingly legitimate HTTP requests that overload servers and databases.
Building a defence
- Detection: flow-based monitoring establishes baselines and flags anomalies within seconds.
- On-premise mitigation: scrubbing appliances or router filtering handle attacks smaller than your link capacity.
- Upstream or cloud scrubbing: large volumetric attacks must be absorbed before they reach your links, via BGP diversion or always-on cloud protection.
- Application protection: rate limiting, bot management and caching protect web services.
Prepare a runbook
Know who declares an attack, how traffic is diverted, which upstream contacts to call and how you communicate with customers. Test it before you need it.
Don’t be part of the problem
Close open resolvers and reflectors on your own network and implement source-address validation (BCP 38) so your infrastructure cannot be used in attacks on others.
Ubixe Infotech designs DDoS detection and mitigation for ISPs and enterprises. See our DDoS Protection service or assess your exposure.
