Cheatsheet Pages / SSH Cheatsheet
How to debug a failed SSH login — ssh -v
Login fails and the error message tells you nothing; the verbose handshake shows which key was offered and where it ended.
Every flag and config keyword was checked against the OpenSSH 9.6 man pages, and the config examples were parsed for real with ssh -G.
ssh -v deploy@example.com # watch the handshake; -vv / -vvv for more detail
# the lines that matter: "Offering public key" → which key was tried,
# "Authentication succeeded" / "Permission denied" → where it ended