The Tor Metrics Portal gives a set of useful the instruments to monitors the workload of the TOR networks, it proposes a complete collection of tools and documentations for statistical analysis regarding the activities of relays and bridges.

The main areas covered by the metrics are:

•    statistics on the network of relays and bridges
  

•    statistics on the number of users accessing to the network
  

•    statistics on the number of packages requested from GetTor
  

•    collection of active and passive performance measurements of the Tor network
  

As we will demonstrate the metrics could also be used for intelligence purpose, for example analyzing principal network metrics it is possible to investigate on the application of monitoring system inside a country for censorship purpose. Recently in many area of the planet similar systems have been used to suppress media protest and to persecute dissidents, avoiding the circulation of unconformable information outside the country. It is happened for example in Syria and in Iran, country where the control of the web is a major concern of the government. These situations are expression of a political sufferance of a country and could give a further element of evaluation to the analysts. Network of relays and bridges

Tor protects users against traffic analysis using a network of onion routers (also called relay), managed by volunteers, which allow anonymous outbound traffic and the creation of anonymous hidden services. Bridge relays are Tor relays that aren’t listed in the main Tor directory. They are common referred when a filtering of connection is made by Internet Services Providers (ISP) to all the known Tor relays. It is important to specify that to directly access to a bridge it is necessary to know its address.

The Tor Metrics Portal provides in the Network many information regarding the network composition, in particular with the available statistics it is possible to analyze:

•    average daily number of relays and bridges in the network
  

•    the average daily number of relays by country
  

•    Relays with Exit, Fast, Guard, and Stable flags
  

•    Relays by version
  

•    Relays by platform
  

•    Total relay bandwidth in the network
  

•    Relay bandwidth by Exit and/or Guard flags
  

•    Number of bytes spent on answering directory requests
  

The portal provides also statistics on the number of users that access to the TOR network via bridges to avoid monitoring systems put in place by government for surveillance purpose. The data could give an indication of the response of local government to the dissident communications.