By default, FTP transmits everything unencrypted — your user name, your password and the files themselves. Anyone able to observe the connection can read them. This is not a theoretical risk: FTP credentials are collected on open networks and reused to upload malicious files to sites.
Use an encrypted connection instead. Two options are available, and both are configured in your FTP client rather than on the server.
FTPS (recommended)
FTPS is FTP with TLS encryption added. In your client, choose FTP over TLS, explicit — sometimes called "explicit TLS" or "FTPES" — with port 21.
In FileZilla, the setting is in the Site Manager: set Protocol to FTP and Encryption to "Require explicit FTP over TLS". Other clients have an equivalent option, usually next to the protocol selection.
Note that implicit TLS on port 990 is an older variant and is best avoided unless you have a specific reason for it.
SFTP
SFTP is a different protocol that runs over SSH on port 22. It is encrypted by default, needs no separate certificate, and can use key authentication instead of a password. If SSH access is available for your account, SFTP is the simplest secure option.
On the first connection
Your client will show the server's certificate and ask whether to trust it. Check that the host name matches the server you are connecting to, then accept it. Connecting by the server host name — vm00000.sayob.com, where vm00000 is your server's identifier — avoids a name mismatch warning, because that is the name the certificate is issued for.
Do not simply switch off certificate verification to make a warning disappear: that removes the protection you enabled encryption for.
If the encrypted connection fails
Check that you selected explicit TLS on port 21 rather than implicit on 990. If the connection is refused entirely, the port may be blocked on the network you are using — try another network before assuming the problem is on the server.
Whatever happens, do not fall back to plain FTP as a workaround. If the encrypted connection will not work, open a ticket from your client area and we will sort it out.
See also: Creating and migrating a site in KeyHelp for creating FTP users.
