Hi, I wrote around half a year ago that FTP is being phased out. Mirrorlist.centos.org stopped giving out FTP URLs around a week ago, and on Friday Fabian changed https://www.centos.org/download/mirrors/ to show HTTPS URLs in the column that used to show FTP URLs. This means there are no longer any FTP URLs pointing to your mirror from centos.org, and monitoring of those FTP URLs has also stopped.
If you feel like it and other distributions that you mirror don't need it, you can now shut down & disable your FTP daemon. There's no need to notify us of your decision, because we no longer have a list of CentOS FTP mirrors that we would need to modify.
As mentioned, the download page now lists HTTPS URLs for those mirrors that offer HTTPS, to the best of our knowledge. If your mirror has HTTPS support and the HTTPS URL isn't listed on the download page, please let us know (maybe off-list) and we'll add your HTTPS link. HTTPS isn't yet used by mirrorlist.c.o and "yum", it's only shown on the download page for the time being. Also, a kind reminder that even if you do support HTTPS, please do not redirect CentOS HTTP mirror traffic to HTTPS. Any such redirects will be treated as an error.
Thanks for your support!