This section is incomplete. Please share your solutions.
Cygwin's ssh works only with a Cygwin version of Emacs. To check for compatibility: type M-x eshell, and start ssh test.host. Incompatibilities trigger this message:
Pseudo-terminal will not be allocated because stdin is not a terminal.
Some older versions of Cygwin's ssh work with the sshx access method. Consult Cygwin's FAQ at http://cygwin.com/faq/ for details.
When using the scpx access method, Emacs may call
scp with Windows file naming, such as
the version of scp that is installed with Cygwin does not
know about Windows file naming, which causes it to incorrectly look
for a host named
A workaround: write a wrapper script for scp to convert Windows file names to Cygwin file names.
When using the ssh-agent on Windows for password-less interaction, ssh methods depend on the environment variable SSH_AUTH_SOCK. But this variable is not set when Emacs is started from a Desktop shortcut and authentication fails.
One workaround is to use a Windows based SSH Agent, such as Pageant. It is part of the Putty Suite of tools.
The fallback is to start Emacs from a shell.