what you mean under "root" login in pure-ftpd? you can log to ftp as root? it is impossible really. if on your server it is possible, this is serious problem and you need urgently reinstall your ftp-server by command /scripts/ftpup --force
if you mean login to ssh as root, this is possible by default and you may disable root login by changing /etc/sshd_config.
Ah Yes it is standart answer on all pure-ftpd servers for disabled or non exist user Just check by using non exist user on your system as login and you will get same answer. Really, i think that this message may changed, but most likely in pure-ftpd compiling time (if you install it from source), but anyway you haven't any reason for worries about security.
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