sudo apt install ipset
sudo ipset create sftp_allowed hash:ip
* añadir: sudo ipset add sftp_allowed 88.26.243.132
== gestión
* listar IPs de un IPSET: sudo ipset list sftp_allowed
* listar IPSETs: sudo ipset list -n
== eliminación
* eliminar IP: sudo ipset del sftp_allowed 203.0.113.10
* vaciar IPSET: sudo ipset flush
* destruir IPSET: sudo ipset destroy