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Misconfigured CenturyLink database caused global internet outage

(Image credit: Image Credit: Atm2003 / Shutterstock)

American ISP CenturyLink suffered an incident that caused an internet outage (opens in new tab) felt all over the world this weekend.

An incorrect Flowspec announcement in the company's data center near Ontario, Canada is said to have caused a technical problem that affected the service of a range of other organizations.

Businesses including Amazon, Twitter, Microsoft (Xbox Live), EA, Blizzard, Steam, Discord, Reddit, Hulu, Duo Security, Imperva, NameCheap, OpenDNS were all affected by the outage.

In total, there was a drop in global internet traffic of approximately 3.5 percent, according to web performance firm Cloudflare (opens in new tab)

As explained by Cisco (opens in new tab), the issue was linked with the BGP (Border Gateway Protocol) flow specification (flowspec) feature, which “allows you to rapidly deploy and propagate filtering and policing functionality among a large number of BGP peer routers to mitigate the effects of a distributed denial-of-service (DDoS) attack over your network.”

Analysis suggested CenturyLink had looped its entire network by announcing new BGP routes and then dropping all of them through the misconfigured Flowspec rule.

To fix the issue, CenturyLink was forced to reset all its gear and start with clean BGP routing tables, which is said to have taken almost seven hours.

This is not the first time CenturyLink experienced an outage on such a large scale. In late 2018 (opens in new tab), a malfunctioning network card took phone and internet services offline for the majority of users, including 911. Some users waited two days for services to be restored.

Sead Fadilpašić is a freelance tech writer and journalist with more than 17 years experience writing technology-focussed news, blogs, whitepapers, reviews, and ebooks. And his work has featured in online media outlets from all over the world, including Al Jazeera Balkans (where he was a Multimedia Journalist), Crypto News, TechRadar Pro, and IT Pro Portal, where he has written news and features for over five years. Sead's experience also includes writing for inbound marketing, where he creates technology-based content for clients from London to Singapore. Sead is a HubSpot-certified content creator.