A node is just a software. You can run many nodes on one machine, so long as it is powerful enough to support multiple nodes.
To run a node, just download and run Bitcoin Core. There is nothing you need to do to secure it as a node does not have anything that requires securing. If you just want to run only a node, you can disable the wallet.
i actually want to built a wallet system for my users based on a secure node. a lot of transactions will come in and out within our own server and outer bitcoin servers.