1. You should establish password less connection to your linux server.
Public keys should be loaded or configured to be loaded automatically.
For putty this means that you should use pagent, for cygwin ssh they
should be placed to your home directory.
2. The error message you sent more look that there is some error in
protocol between client and server. Usually this caused by
incompatibility of client and server version of CVS. To resolve this
issue configure plug-in to use cvs.exe (cvs client) that is know for
you as compatible with your server (i.e. that is shipped with WinCvs
or other working client). Please check this page for details:
http://www.pushok.com/soft_cvs_faq.php?#2Let me know if this not help