Measurements of NAT/firewall characteristics
We have conducted a study of different NATs and firewalls existing in the Internet by measuring the Tribler system.
Hereby we present the results we obtained from our measurements in the period between 27/10/2008 and 25/11/2008, during which we collected data from a total of about 3500 unique peers.
The classification of users' connection type has been done according to STUN http://en.wikipedia.org/wiki/Network_address_translation, http://tools.ietf.org/html/rfc3489.
We have then geo-located the Tribler users involved in our measurements and found out that the connection type distribution has a similar trend in major countries.
The term timeout refers to the duration of a given mapping in the NAT/firewall when not used for a while (i.e. after how long a mapping in a NAT/firewall expires if there is no communication going through). This information is especially useful for tuning the frequency of keep-alive packets in NAT traversal techniques.