Get ssh thumbprint or ssh fingerprint of every entry in known_hosts as json:
ssh-keygen -l -f known_hosts | awk '{ print "{" "\042host\042:\042" $3 "\042" ",\042thumbprint\042:\042" $2 "\042" ",\042alg\042:\042" $4 "\042" ",\042size\042:\042" $1 "\042" "}"}' | sort | jtbl
formatted:
ssh-keygen -l -f known_hosts \