ftptop(1) on Linux
The text 3461caf4cdc2, as Debian 7 (Wheezy), Debian 6.0 (Squeeze) shipped it.
display running status on proftpd server connections
Flags it lists
-
-A -
-D -
-I -
-S -
-U -
-V -
-a -
-d -
-f -
-i