Hello,

To understand the differences between FTPS and SFTP protocols please visit our Secure FTP disambiguation page. FTPS is supported by Rebex FTP/SSL component, SFTP is suported by Rebex SFTP component. Both feature a similar API and are also available as a bundle - Rebex File Transfer Pack

How to connect and login using the Ftp or Sftp class respectively is described in the FTPS tutorial or SFTP tutorial respectively.

How to authenticate with a client certificate using the Ftp class is described in the FTPS tutorial How to authenticate with a public key using the Sftp class is described in the SFTP tutorial

This is how to get file length of the remote file using Ftp class:

Ftp client = new Ftp();
// ... connect and login ... 
// get file length
long fileLength = client.GetFileLength(remotePath);

This is how to get file length of the remote file using Sftp class:

Sftp client = new Sftp();
// ... connect and login ...
// get file info
SftpItem item = client.GetInfo(remotePath);
// get file length
long fileLength = item.Size;