How do I set the default values of directories and files created to be 775 ? My understanding is that I need to modify the umask on VSFTPD, but how do I know what to change it to?
Umask and final permissions that you need should add up to 777. Since you need 775 permissions, you need 777 - 775 = 002 as umask.
In case you are wondering where to set your umask, it can be set in the vsftpd config file (/etc/vsftpd.conf) as
For the mask to work properly (even without anonymous access) it seems necessary to set
In your case, if you need user-authenticated access, you should set the following:
Further reading: https://security.appspot.com/vsftpd/vsftpd_conf.html