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The client should now be able to connect via SSH to the openssh server.

Generating a (new) separate key and using it for a specific host

You might want to use a separate key for a specific host.  For example, let's create a key called gitlab_jaytaala for use with in pushing/pulling to/from gitlab.jaytaala.com:

ssh-keygen -t rsa -f .ssh/gitlab_jaytaala

To get your machine to use this key for a specific host (for example from the terminal) we create an the following config file within your .ssh folder:

vim .ssh/config

and add the following:

Host gitlab_jay 
    HostName gitlab.jaytaala.com
    IdentityFile ~/.ssh/gitlab_jaytaala
    User j.taala

You can add another section as above for other hosts.  Note that indentation is not required (but does make it much easier to read given lots of Host directives).

In the above example, having defined the host gitlab_jay  we can then simply do:

ssh gitlab_jay

to connect by ssh to host gitlab.jaytaala.com. 

References

1. https://help.ubuntu.com/lts/serverguide/openssh-server.html
2. https://linuxize.com/post/using-the-ssh-config-file/

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