from the server in question:
```
root@tate:~# ssh-keygen -lf /etc/ssh/ssh_host_ecdsa_key.pub | awk '{print $2}'
SHA256:0gi9tkEMHCDIveSm/VbZhdp8T83PlmWlufyli5OKrvg
```

from my laptop:
```
$ /usr/bin/ssh-keygen -l -F forge.softwareheritage.org
# Host forge.softwareheritage.org found: line 146
forge.softwareheritage.org ECDSA SHA256:0gi9tkEMHCDIveSm/VbZhdp8T83PlmWlufyli5OKrvg
```