known_hosts in hash format - OpenSSH

When you wonder why your known_hosts file has changed or you don't find your hosts:

|1|AEf8B/QCP+1wRKA761Cq/woad4s=|HVEWXKDdRpZmO3GeQ5T37xCFwgE= ssh-rsa AAAAB3NzaC1
yc2EAAAABIwAAAQEAt20HN/iasjy9KEW/BGjtxlsy8oebyEEnZvKAnjMck0EEVbA5rtE4dzisnbrYwZ4
67JP+p9UGZDQa4jbVo2ZHmz28nQapmw1WpLBD2wSN66PsMk5QCxICxBC6PDCOlwakQvLNES2B9R2cuev
G9Ag2ni+2Qdb17gEkkh2MZ91INylAzM7QWW7soGoSf1TsshSHexfMt12zb6kWxRuRCeT4fOzlJNOmPgr
uE3wTt/kfEbvPBZwDyUbEKApfYIxO8ic+FyO7qFEjHkhqT7px/oJMLS279uUHlhG+KWtPxYPhWaYulPZ
hhdn4D6pR+6shjPsH4VTyAUGwf7usKUvJZP59Ww==

Then your ssh server software is a new version which hashes the known hosts file entries. To remove entries from there because the host key differs (you installed the host completely from scratch), just type:

ssh-keygen -R hostname

or

ssh-keygen -R ipadress

That's it.

If you have a new ssh package, you may hash yourself your known_hosts file by typing:

ssh-keygen -H