7.7 FTP and empty path parts in the URL
7.8 Premature transfer end but healthy control channel
7.9 Passive transfer tries only one IP address
+ 7.10 Stick to same family over SOCKS proxy
8. TELNET
8.1 TELNET and time limtiations don't work
See https://github.com/curl/curl/issues/1508
+7.10 Stick to same family over SOCKS proxy
+
+ When asked to do FTP over a SOCKS proxy, it might connect to the proxy (and
+ then subsequently to the remote server) using for example IPv4. When doing
+ the second connection, curl should make sure that the second connection is
+ using the same IP protocol version as the first connection did and not try
+ others, since the remote server will only accept the same.
+
+ See https://curl.haxx.se/mail/archive-2018-07/0000.html
8. TELNET