Starting at 10:26 UTC on Thursday, 29 November (12:26pm in Damascus), Syria's international Internet connectivity shut down. In the global routing table, all 84 of Syria's IP address blocks have become unreachable, effectively removing the country from the Internet.
We are investigating the dynamics of the outage and will post updates as they become available.
Update (15:45 UTC)
Looking closely at the continuing Internet blackout in Syria, we can see that traceroutes into Syria are failing, exactly as one would expect for a major outage. The primary autonomous system for Syria is the Syrian Telecommunications Establishment; all of their customer networks are currently unreachable.
Now, there are a few Syrian networks that are still connected to the Internet, still reachable by traceroutes, and indeed still hosting Syrian content. These are five networks that use Syrian-registered IP space, but the originator of the routes is actually Tata Communications. These are potentially offshore, rather than domestic, and perhaps not subject to whatever killswitch was thrown today within Syria.
These five offshore survivors include the webservers that were implicated in the delivery of malware targeting Syrian activists in May of this year.
It has been a crazy year for Syrian Internet transit arrangements, most recently with the loss of Deutsche Telekom as a transit provider earlier this month.
Update (20:30 UTC):
Still no signs of life from the affected prefixes. Looking back over the last week, you can see that the routing of the Syrian Internet has actually been pretty stable until today's wholesale shutdown.
There have been some brief up-and-down flickers affecting the reachability of a particular 12 networks, and there was one brief whole-country outage of less than ten minutes on 25 November. By the time that one was confirmed, the outage was over. It would be reaching to call that a "precursor event" or "practice run," but that's a possibility.
Also, some have asked about the submarine connectivity into Syria. Here's a map showing the three principal routes. There's also terrestrial connectivity into Turkey to the north, but those paths have not been reliable in recent months.
Update (01:00 GMT, 30 Nov):
The last 5 networks belonging to Syria, a set of smaller netblocks previously advertised by Tata Communications, have been torn down and are no longer routed. These blocks survived today's Internet blackout in Syria, but 12 hours after the onset, they, too are off the air. Traceroutes to these blocks now die on Tata's network in New Jersey, and websites hosted in these blocks are no longer responding.