The first time you login to Teach cluster you'll be asked to confirm the ssh host key fingerprints:
$ ssh teach.scinet.utoronto.ca The authenticity of host 'teach.scinet.utoronto.ca (184.108.40.206)' can't be established. ED25519 key fingerprint is b4:ae:76:a5:2b:37:8d:57:06:0e:9a:de:62:00:26:be. Are you sure you want to continue connecting (yes/no)?
Make sure the fingerprints are correct! You should see either one of the ED25519 fingerprints:
ED25519 key fingerprint is SHA256:SauX2nL+Yso9KBo2Ca6GH/V9cSFLFXwxOECGWXZ5pxc. ED25519 key fingerprint is MD5:b4:ae:76:a5:2b:37:8d:57:06:0e:9a:de:62:00:26:be.
or one of the following RSA fingerprints:
RSA key fingerprint is SHA256:k6YEhYsI73M+NJIpZ8yF+wqWeuXS9avNs2s5QS/0VhU. RSA key fingerprint is MD5:98:e7:7a:07:89:ef:3f:d8:68:3d:47:9c:6e:a6:71:5e.
depending on how old your ssh client is and how it is configured.