10 May CWRsync user authentication errors when installed on Windows 7
Just a short and simple support issue this time, but one that we have seen a couple of times now so I thought it was worth sharing.
If you are planning on using the opensource Windows Rsync server ‘CWRsync‘ on a Windows 7 machine you may want to follow this guide before configuring any user accounts.
The first time we came across this issue was with a customer who was trying to configure the Rsync component in their BackupAssist installation to connect to a remote CWRsync server using ‘Rsync over SSH‘. They had followed the installation guide to the letter but every time they tried to register BackupAssist with the server they would get ‘Access Denied‘ errors. This would usually suggest that either the username or password was incorrect but after much double checking and recreating of accounts it became clear something else was stopping the authentication from working as expected.
The clue came from looking in the CWRsync session logs where it became clear that the username was actually being logged as DOMAIN\\username. This was odd because it was entered into BackupAssist as ‘DOMAIN\username’
(Note the single backslash became duplicated).
After a little more digging the issue was pinned down to a Windows User Access Control problem. Even through UAC settings were reduced to the minimum settings the act of configuring the user within the CopSSH control panel was not working correctly when run as the local user within Windows.
The fix is to first remove the user from COPSSH if you have already set it up, then to re-run the COPSSH control panel as the administrator account by right clicking on the short cut and choosing ‘Run as Administrator‘. 
The process of setting up the user is correct but by explicitly running as an administrator account provides the application the correct rights to create the relevant home folder for the user and the subsequent authentications should work as expected.
Ref: https://www.itefix.no/i2/content/cannot-log-copssh
UPDATE:
In some instances I have seen that when the user is added into CopSSH control Panel and the prefix is actually the computer name and not a domain then you will need to authenticate using just the username for example if the server is named ‘SERVER01’ in CopSSH you would see a username of ‘SERVER01\user’ but in BackupAssist you would authenticate as just ‘user’
UPDATE 2:
We had another customer with an authentication today and there issue was that even though they were using a domain user in COPSSH it was not showing the domain correctly. After descussing the issue they googled and actually found a different answer that resolved there issue here. https://www.itefix.no/i2/content/adding-active-directory-users-when-domain-doesnt-show-copssh-control-panel