In a word: lftp – a sophisticated file transfer program.
So for example you want to transfer a massive Zope Data.fs file from an ftp server and you don’t have ssh access and can’t use rsync. Amongst it’s many features lftp lets you limit the number of connections to the server and the amount of bandwidth to consume. It is also installed by default on many Linux distros.
To configure it you need to add or edit ~/.lftp/rc
to set it to 1 connection at 1Mb/s (given in bytes) use the following
set net:connection-limit 1
set net:limit-rate 131072
If you can connect ok but everything you try to do (e.g. ls) gives you something like this:
Fatal error: SSL connect: error:00000000:lib(0):func(0):reason(0)
then you also need to explicitly turn ssl off
set ftp:ssl-allow false
An important practical use for this it to prevent an ftp dowload from interrupting your listening to weenradio