T644 offers a world listening etcd on ports 4001 and 7001.

The risk should be evaluated and any ACL / IP control / private network strategy put in action.

Reference

• Client/server certificates - https://github.com/coreos/etcd/blob/master/Documentation/security.md
• Tool to ease that: https://github.com/coreos/etcd-ca, documented at:
  • http://blog.dixo.net/2015/05/setting-up-a-secure-etcd-cluster/
  • https://medium.com/@gargar454/coreos-etcd-and-fleet-with-encryption-and-authentication-27ffefd0785c