As the civil war rages on in Syria, Internet service was reportedly cut off nationwide on Thursday. Cellphone service has reportedly also been cut in "select areas," and landlines are said to be "working only sporadically."
According to Reuters, this disruption in communications is the worst Syria has seen since the civil uprising began 20 months ago.
The Associated Press and other news agencies have pinpointed the Syrian government as the culprit behind the Internet shutdown.
However, as the Jerusalem Post notes, Syria's minister of information appeared on a pro-government TV station on Thursday saying that "terrorists," not the state, were responsible for the Internet outage.
But, tech blog Cloud Fare, citing technical evidence, has disputed this claim, saying that "from our investigation, that appears unlikely to be the case."
While the question of why this online blackout was instituted is still up for speculation, the matter of how this shutdown was carried out is better understood.
Rob Faris, Research Director at Harvard University's Berkman Center for Internet & Society, told The Huffington Post that the "most likely" method used by Syrian authorities to conduct this blackout was to "tweak the routing tables," essentially blocking the transference of information by sending it all into a cyber "blackhole."
"If a country wanted to remove itself from the Internet, it can," Faris told HuffPost. "There are a limited number of international gateways, and it's really just a matter of how many telephone calls need to be made."
"Within any major router, there are a series of routing tables that describe which set of IP addresses should go where, and all you have to do is you change the direction of that map," he continued.
Cloud Fare has a thorough explanation on its site:
The exclusive provider of Internet access in Syria is the state-run Syrian Telecommunications Establishment. Their network AS number is AS29386. The following network providers typically provide connectivity from Syria to the rest of the Internet: PCCW and Turk Telekom as the primary providers with Telecom Italia, TATA for additional capacity. When the outage happened, the BGP routes to Syrian IP space were all simultaneously withdrawn from all of Syria's upstream providers. The effect of this is that networks were unable to route traffic to Syrian IP space, effectively cutting the country off the Internet.
This method, experts said, was probably what Egypt's government used to shut down its own Internet in 2011.
As an earlier CNN report notes, Egyptian authorities "likely called the country's five main internet service providers ... and ordered them to barricade online traffic."
It's akin, said Faris at the time, of "calling all of the post offices in the country and telling them to throw the mail away instead of delivering it."
"It's not as complicated as people think it is. It's just a question of having the power to tell the people who are running the ISPs to do what you want them to do," Faris told HuffPost. "And in Syria's case, the answer is clear."
Faris added that while this is the easiest way to cause an Internet shutdown, it is not the only way. Cables could also be removed or cut, electricity turned off and filters could be "cranked up a lot," thereby blocking applications, ports, etc.
"What Iran has done in the past is it has throttled bandwidth," he said. "So keeping the Internet open but reducing bandwidth so much that it can't support most applications."
Syria and Egypt are not the only countries that have imposed Internet shutdowns during times of crisis. In 2007, the Burmese government pulled the plug on the Internet following its "violent crackdown on protesters there," Open Net notes. In Nepal, the Internet has been blacked out a number of times.
As The New York Times notes, the Internet has played a pivotal role in the Syrian conflict so far, being used as a "strategic weapon" by both the government and the uprising:
The Internet has been a strategic weapon for the uprising and the government alike, allowing activists to organize and communicate but also exposing them to surveillance. Fighters activists and ordinary citizens upload video of rebel exploits and government crackdowns but also exposing rebel atrocities -- making the Syrian conflict one of the most documented conflicts with the sheer amount of material available.
The question of why the Internet been blacked out still remains unanswered.
"Clearly something is going on there and that's the whole point," Faris explained. "They haven't done it arbitrarily… they could have done it at any time and they haven't, so to do so now ... it's clearly a conscious decision, but I'm not sure what it is."
"They're probably trying to prevent some sort of information from leaving the country, and that's particularly worrisome," he speculated.
According to The New York Times, activists suspect that the shutdown may indicate that the military is planning an escalated response against the uprising.
Still, despite the blackout, it seems that Syria may still have a way to access the Internet. In response to the shutdown, Twitter users from around the world have been stepping forward with dial-up numbers to help Syrians get online:
However, if the phone lines are cut, this method will also become unavailable.
Nonetheless, Faris argues, information will reach the wider world from Syria -- no matter how difficult its passage is.
"I'm interested to see activists and those supporting the activists as they come up with alternative channels," he said. "To think that this won't be documented, it's wrong. People still have cellphones and can take photographs... A very important part of the struggle is control over information and a big part of what the opposition is doing is getting this information out and people will put their lives at risk to do so."
View the slideshow to see how Twitter users are reacting to the blackout in Syria.