OpenSSH is the implementation of the SSH protocol. OpenSSH is recommended for remote login, making backups, remote file transfer via scp or sftp, and much more. SSH is perfect to keep confidentiality and integrity for data exchanged between two networks and systems. However, the main advantage is server authentication, through the use of public key cryptography. From time to time there are rumors about OpenSSH zero day exploit. Here are a few things you need to tweak in order to improve OpenSSH server security.
FTP is insecure protocol, but file-transfer is required all time. You can use OpenSSH Server to transfer file using SCP and SFTP (secure ftp) without setting up an FTP server. However, this feature also grants ssh shell access to a user. Basically OpenSSH requires a valid shell. Here is how sftp works: SCP/SFTP -> SSHD [...]
rssh is a restricted shell for providing limited access to a host via ssh. It also allows system wide configuration and per user configuration. From the man page: The user configuration directive allows for the configuration of options on a per-user basis. THIS KEYWORD OVERRIDES ALL OTHER KEYWORDS FOR THE SPECIFIED USER. That is, if [...]
rssh support chrooting option. If you want to chroot users, use chrootpath option. It is used to set the directory where the root of the chroot jail will be located. This is a security feature. A chroot on Linux or Unix OS is an operation that changes the root directory. It affects only the current [...]