We suggest using an open-source software client, such as Bitcoin Core, so that its code can be fully audited and verified to be secure.
Traffic on the Bitcoin network is not encrypted, which means if you run a Bitcoin node, your internet service provider (ISP) will be able to see that you are running a node. However, take comfort in knowing they are unable to alter your transactions, as any change would require a new signature with your private key.
To keep your node private, use TOR (the onion router) to connect to the outside world. Alternatively, you can use a VPN (virtual private network) to obscure the traffic from your node, but be aware that many VPN providers keep logs and will hand them over to third parties upon request.
Most, if not all, of the node distributions we listed previously support and integrate TOR connectivity. This also makes it easier for you to connect to a self-hosted node from the internet.