Assuming that file names can also have leading and/or trailing spaces in them, for example ' file name ' then you may want something like this:

while ( <$in> ) {
    chomp;
    my %field;
    # remove and capture leading fields
    s/^ *(\S+) (\S+) +(\d+) ([\d:]+) (\d+) (\d+) ([\d.]+) (\d+) // and
        @field{ qw/ day_name month day current_time year transfer_time
+ remote_host file_size / } = ( $1, $2, $3, $4, $5, $6, $7, $8 );
    # remove and capture trailing fields
    s/ (\S+) (\S+) (\S+) (\S+) (\S+) (\S+) (\S+) (\S+) (\S+)$// and
        @field{ qw/ transfer_type special_action_flag direction access
+_mode username service_name authentication_method authenticated_user_
+id completion_status / } = ( $1, $2, $3, $4, $5, $6, $7, $8, $9 );
    # only thing left is file name
    $field{ filename } = $_;

    print "$_ = '$field{$_}'\n" for keys %field;
    print "\n";
    }
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