Problem with DNS connection to the node from Linux

Hi everyone.

I’m quite new to Linux/SSH/DigitalOcean so I might did something inpriopriate while configuration of nodes connections. I started to work with Swarm and decide to work with DigitalOcean. I’ve tried to follow instruction in tutorial about configuring nodes connections.

I’m working on Ubuntu 20.04 What have I already done?

• I’ve generated my RSA keyPairs,
• I’ve generated 3 nodes in digital ocean with adding my public key during setup,
• To avoid using nodes IP adresses, I’ve configured my local DNS server by adding to ’ home/etc/hosts’ values: {node1IP} node1 … (What I’ve found this is a necessary to use in the future something like ‘ssh node1’ instead of ‘ssh root@{node1IPAdress}’)
• According to tutorial (link at the beginning), I’ve created /etc/ssh/config file with content like: Host node1 HostName node1 User root …{node2, and 3 the same}

Effect: I can connect to the node with standard ssh root@{nodeIPAddress} but when I try to connect like ‘ssh node1’ then I receive an information ‘Permission denied (publickey)’.

What is interesting? When I try to connect to the node for the first time I receive message: 'The authenticity of host ‘node1 (nodeIp)’ can’t be established. ECDSA key fingerprint is SHA256:31{restOfFingerpring} Are you sure you want to continue connecting (yes/no/[fingerprint])? ’ But what I don’t understand is a fact that this particular fingerprint is not the same which I’ve generated in the begiinning (generating RSA key). I don’t know if ECDSA key fingerprint should be or not to be the same.

I’ve searched many website to somehow find out what is a problem, but with no effect (despite better understanding of ssh and protection :) ).

Thank you in advance for any ideas/help.