What is Freenet?
Freenet is a way to communicate securely, anonymously, and without fear of censorship. Freenet is a network of computers that store and retrieve files. Freenet is the software that you run on your computer in order to join the network, retrieve files that are on the network, and store new files on the network.
What is FProxy? What is Fred?
Fred is the Freenet REference Daemon. It is the software that runs all Freenet nodes (computers on the Freenet network). FProxy is the part of Fred that provides a web browser interface; it is used both to configure and control Fred, and to view files and freesites that are on Freenet.
Connecting to the network
What is darknet?
A darknet, for Freenet purposes, is a network where node connections are created manually by the users of the nodes via invitations. These connections should be made on the basis of mutual trust, friendship, or acquaintance. If they are, then the network should have a small world topology and routing will work, especially since darknet peers are more or less permanent. If the connections are made completely at random, then the network topology will be wrong, and routing will not work.
In darknet mode, Freenet uses location swapping to create a routable network. Unlike opennet, darknet connections are outside of the control of the node. However, the underlying social network will have the correct topology, and so will the resultant darknet. Location swapping is used to assign routable location to nodes on the network.
What is opennet?
An opennet, for Freenet purposes, is a network where connections are automatically created by the node. The node comes prepackaged with a list of seed nodes to which the node may connect. Once a connection is established between the node and the seed nodes, the seed nodes provide a list of more nodes to connect to, and they do they same, etc. This process happens continually while the node is running, without any user intervention.
Security: How should I connect to the network?
Though opennet is much easier for the user (compared to creating connections in a darknet), it is vulnerable to harvesting, and therefore can be blocked very easily.
This was a known problem with Freenet 0.5, and it led to it being blocked by the evil Chinese firewall.
A darknet is not harvestable because your node reference will never be passed on by the network to any other node. Therefore, an attacker running a darknet node can only see those nodes which he has managed to get invitations to connect to.
Consequently, you are vulnerable primarily to the nodes you are connected to. Thus, it is a good idea to only connect to people you trust, if this is possible.