/etc/lftp.conf

...
# set net:limit-total-rate rx:tx  # rx, tx in bytes/s.
#Limit receive to 1 Mo/s
set net:limit-total-rate 1048576:0
#Limit emmit to 50 Ko/s
#set net:limit-total-rate 0:51200

1 Byte = 8 Bit
1 Kilobyte = 1,024 Bytes
1 Megabyte = 1,048,576 Bytes
1 Gigabyte = 1,073,741,824 Bytes
1 Terabyte = 1,099,511,627,776 Bytes

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