Files are exchanged using the FTP(S) protocol, port 21. Encryption of messages based on the ftp(e)s (FTP over SSL) protocol is mandatory.
CB currently only supports TLS 1.2, data channels are limited to port range 41000:42000. To use encrypted FTP, your FTP client software must support this.

Web services and websites are secure as soon as they contain confidential data.

CB makes FTPs (SSL encryption) 'FTP over TLS mandatory' but still allows 'Plain text FTP'. As of March 1, 2025, 'Plain text FTP' is no longer permitted.

When digital communication is used, an FTP account is created on ftp1.boekhuis.nl. The files can be placed for CB via this account and the desired files will be prepared by CB. The login details for the FTP account will be sent to you by CB after activating the FTP account.

Kenmerken FTP account
/Relation id/	Home directory
	in/	folder for files from Customer to CB	Files placed are moved by CB immediately after receipt for syntactic checking and further processing. After placing the file, it is not allowed to edit it. A receipt confirmation is automatically placed in the out folder for placed files.
	out/	folder for files from CB to Customer	Files that are downloaded or opened will be automatically deleted from the ftp server. Files that are not retrieved, CB will delete after some time.
Directories and subdirectories may not be created.

The filename pattern of a file consists of two parts, the part before and after the 'dot'
before the 'dot'	filename
after the 'dot'	extension (lower case letters)
The file name may be constructed using numbers 0 to 9, the letters a to z (capital and/or lower case) and the special characters “dot “ (.), dash (-) and underscore (_). All other characters such as space, diaeresis, &, <, >, {, } etc. are not allowed. The extension does not allow the use of capital letters.

Connection with ftp server - Transfer mode
Frequency of logging into the server should not be more than once every 10 minutes. You must log out at the end of each session. Parallel login sessions for the same file are not allowed.
Transfer mode	The PASV command (passive mode) must be used for the connection
Binair	all files with the extensions '.epub', '.jpg', '.pdf' and '.zip'
ASCII	all other extensions