Package: openssh-client Version: 1:8.1p1-1 Severity: wishlist ssh man page says:
~/.ssh/known_hosts
Contains a list of host keys for all hosts the user has logged
into that are not already in the systemwide list of known host keys. See
sshd(8) for further
details of the format of this file.
Alas, one needs to install the openssh-server package to see this page.
Despite being a need of simple clients.

