来自官方的issue回答：

First of all, you should use -c <community.list file name> at the supernode. The plain text file contains all allowed community names. Only listed communties will be allowed to connect then, so keep the name secret. A sample community.list file (including more detailed information also about advanced features) should come with n2n.

As the community name is transmitted in plain text by default, sniffing would reveal it. That is why you should enable header encryption (-H) at all the edges. Header encryption is a per-community setting; all edges of one community need to either have it enabled or disabled.

Going with this configuration, only edges knowing the right community name (-c <community.list file name>) will be able to register to the supernode and join the community.

You might find our FAQ helpful.