Network Permissioning

Network Permissioning is a feature that controls which nodes can connect to a given node and also to which nodes the given node can dial out to. Currently, it is managed at the individual node level by the --permissioned command line flag when starting the node.

If the --permissioned flag is set, the node looks for a file named <data-dir>/permissioned-nodes.json . This file contains the whitelist of enodes that this node can connect to and accept connections from. Therefore, with permissioning enabled, only the nodes that are listed in the permissioned-nodes.json file become part of the network. If the --permissioned flag is specified but no nodes are added to the permissioned-nodes.json file then this node can neither connect to any node nor accept any incoming connections.

The permissioned-nodes.json file follows the below pattern, which is similar to the <data-dir>/static-nodes.json file that is used to specify the list of static nodes a given node always connects to:


Sample file: (node id truncated for clarity)



In the current implementation, every node has its own copy of the permissioned-nodes.json file. In this case, if different nodes have a different list of remote keys then each node may have a different list of permissioned nodes - which may have an adverse effect. In a future release, the permissioned nodes list will be moved from the permissioned-nodes.json file to a Smart Contract, thereby ensuring that all nodes will use one global on-chain list to verify network connections.