I've been running a Linode droplet for several years with no problems. In the last month, users have reported FTP connection errors, always related to Passive FTP.
Investigation shows that the nf_conntrack_ftp module is no longer loaded. We use this module to allow iptables to properly handle passive ftp connections.
Apparently this module has vanished from the system! modprobe nf_conntrack_ftp yields "FATAL: Module nf_conntrack_ftp not found."
I have rebooted the linode and retried.
I'm not sure what to do at this point. Any suggestions? Thanks!