Порт 2380 (etcd Peer)

TCP port 2380 is commonly associated with `etcd`, a distributed key-value store used for service discovery, configuration management, and cluster coordination. Specifically, port 2380 is used for etcd peer communication. Etcd forms a cluster of nodes, and these nodes need to communicate with each other to maintain data consistency and elect a leader. This communication happens over the peer port (2380 by default). The Raft consensus algorithm is used to ensure that all members of the cluster agree on the state of the data. This involves leader election, log replication, and ensuring that updates are applied in a consistent order across the cluster.

At a technical level, when an etcd node needs to propose a change to the cluster, it sends the proposal to the leader. The leader then replicates the proposal to the other nodes (followers) in the cluster over port 2380. Each follower acknowledges receipt of the proposal. Once a majority of the nodes have acknowledged the proposal, the leader commits the change. The leader then informs the followers that the change has been committed, and they apply the change to their local data store. The protocol used over port 2380 is typically based on gRPC, which provides a high-performance and efficient way to serialize and transmit data between nodes. Authentication and authorization are crucial aspects of this communication to prevent unauthorized access and manipulation of the cluster's data.

## Firewall Recommendations

It is highly recommended to restrict access to port 2380 to only those nodes that are part of the etcd cluster. This means that only the etcd nodes themselves should be able to communicate on this port. Block all other traffic. If etcd needs to be accessed from outside the cluster for management purposes, use a secure tunnel or VPN. Avoid exposing port 2380 directly to the internet. Implement strong authentication and authorization mechanisms for etcd, and regularly rotate credentials. Regularly monitor etcd logs for suspicious activity and keep the etcd software up to date with the latest security patches. Consider using TLS encryption for all etcd peer communication to protect data in transit.