Investigate restricting communication for security

There are various techniques to prevent an adversary for creating numerous identities and overflowing the network. Latency is restricted by the laws of physics, thus a peer 5ms away has to be reasonable close. Geo-fencing is a well known term to restrict activity to an region by using GPS technology. One measure we could take is create a low-latency overlay. Peers with inherent 100+ms connections could possible take longer to bootstrap trust or overlay peers.

Another approach is to use the multichain mechanism. For instance, in darknet mode: the policy is to deny any connection with strangers.
Then we start to deviate fundamentally from the random-circuit building approach, used in Tor. In our fully distributed setting it is difficult to protect yourself from various kind of attacks, like the Sybil attack. By not accepting connections from strangers we constrain a lot of attack classes. Every Tribler user that has a healthy set of neighbors to relay traffic with shall not interact with strangers.

Drawbacks: bootstrapping new peers. Do we need to leave hard-limited room for new peers?
Positive: low-latency overlay boosts fast research results and regional content

EDIT: latest insight (2019) is that diversity of latency is much simpler to implement and also proven to be quite effective (perhaps not as intuitive that latency diversity is as effective as shielding yourself from far-away nodes.