I am making a new Ubuntu machine as a server, which is supposed to replace an old one with older software.
My question is:
Is it possible to transfer/copy the credentials (in terms of SSH) of the old machine/server to the new machine?
My goal is such that the new machine should supplant the old one and be seen by others as the same machine when using SSH. In other words, I want to ease the upgrading of my network without having to reset SSH-based credentials if one server (and in particular its OS) is replaced.
-- Update --
My specific goal was to transfer credentials for the server only, but I do use ssh to replace password based login sometimes, and the suggestions on the client/server connections are also very helpful.