Is there a way to restrict FTPS ports on both the server & client side of the connection?
I've already read this answer and I have vsftpd set to restrict passive port usage to a narrow range on the server side. I've verified that this restriction does work -- for the server. However, if the client is behind a firewall itself and is carefully restricting access on that end, the connections fail. Inspecting with tcpdump, it appears that arbitrary high ports on the client side are being used.
SFTP is not an option. (Believe me, I wish it were.)