Looking into Iran's portion of the Internet is not an easy task.

But the network security firm Arbor Networks recently released traffic data for both internal and external-facing Internet service providers in the country. This data shows that the country continues to filter Internet traffic and that its ISPs can filter larger quantities of data than before.

Arbor Networks uses data gathered from distributed network sensors to monitor the data going to Iran from the global Internet.

In a post on Sunday, the firm showed that the overall trend for the first three weeks of July was an increasing amount of traffic headed into Iran. The country has a single national provider that handles Internet traffic, but a handful of internal providers. The picture painted by the data is of an ISP that is becoming increasingly skilled in filtering, says Craig Labovitz, chief scientist for Arbor Networks.

"It was speculated early on that they lacked capacity," Labovitz says. "It wasn't that traffic was being filtered, it was that it was being dropped because they lacked capacity. Now, it looks like they are navigating 5 gig of traffic again, and I don't think they have turned off filtering."

In a second post on Tuesday, Labovitz showed some interesting patterns in the traffic heading to six of the country's internal network providers. All of the providers showed an enormous drop in traffic following the contested June 12 election, then nearly normal traffic patterns until June 26, then five of the six ISPs showed an 80 percent drop in traffic for approximately three weeks. The one internal ISP that continues to see significant traffic during those three weeks counts many government ministries among its clientele.

Because Iran does not have many connections with global businesses, and very little consumer penetration of the Internet, the populace will likely not complain about the filtering as much as, say, China, where expectations of the Internet are much higher, Labovitz says.

"China's filtering is a much more substantial effort involving business partners and business development relationships involving partners," he says. "It is a much broader business ecosystem that China has evolved over time."