Please follow these instructions to install your SSL certificate on ProFTPD Server:
1. Once you received your SSL certificate by e-mail, please copy and paste it into a text file and save the file with the .cer extension. (Include the tags -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----).
2. /ROOTS|Get your intermediate certificate. Copy and paste the contents into a .cer file by using a text editor and save it as root.cer.
3. Copy your SSL certificate file (from step 1) into the directory that you will be using to hold your certificates. We will use /etc/ftpd/ in this example where the public (ftp-yourdomain-com.cer) and private key (private.key) files are already.
4. In the Virtual Hosts settings for your site, complete the following in the proftpd.conf file:
TLSEngine on
TLSLog /var/ftpd/tls.log
TLSProtocol SSLv3 TLSv1
TLSRequired off
TLSRSACertificateFile /etc/ftpd/ftp-yourdomain-com.cer
TLSRSACertificateKeyFile /etc/ftpd/server.key
TLSCACertificateFile /etc/ftpd/root.cer
TLSVerifyClient off
TLSRenegotiate required off
5. Save your proftpd.conf file and restart ProFTPD.