Get fingerprints:
# bash
for file in /etc/ssh/ssh_host_*_key; do ssh-keygen -l -f "$file"; done
# fish
for file in /etc/ssh/ssh_host_*_key; ssh-keygen -l -f "$file"; end
Regenerate keys:
# remove old and unused keys
rm /etc/ssh/ssh_host_*key*
# create new
ssh-keygen -N '' -o -t ed25519 -f /etc/ssh/ssh_host_ed25519_key
ssh-keygen -N '' -o -t rsa -b 4096 -f /etc/ssh/ssh_host_rsa_key
ssh-keygen -N '' -o -t ecdsa -b 521 -f /etc/ssh/ssh_host_ecdsa_key