Wired reports that the cyber-crackdown includes the shut down of texting and Blackberry messaging.

All basic Internet service in and out of Egypt was totally blocked as of midnight Thursday in Cairo.

The Washington Post, quoting an anonymous U.S. official on the breadth of the clampdown, reports:

"The Egyptian shutdown, if continued Friday, could be the most drastic move against anti-government activists' use of technology since the Iranian government cracked down on protests in 2009. The U.S. official, who was not authorized to speak on the record, said the actions to shut down the Internet and cellphones began after midnight Thursday.

Cairo and other cities were girding for what activists labeled "Angry Friday," a pivotal moment in their newly energized campaign to oust President Hosni Mubarak."

Egyptian protesters, much like mobilized civilians in Tunisia earlier this month, have been heavily relying on Twitter, smartphones and other social media not only to rally their supporters but also to seek international support.

Here's a guide on how to follow Egyptian events on social media as the protests continue to unfold.