FUNCTION interact$(command$, connection, use_pasv)

    LOCAL pasv$, data$, response$
    LOCAL port, passive

    IF use_pasv THEN
        SEND "PASV" & NL$ TO connection
        RECEIVE data$ FROM connection
        pasv$ = INBETWEEN$(data$, "(", ")")
        port = VAL(TOKEN$(pasv$, 5, ","))*256 + VAL(TOKEN$(pasv$, 6, ","))
        OPEN "localhost:" & STR$(port) FOR NETWORK AS passive
    ENDIF

    IF LEN(command$) THEN SEND command$ & NL$ TO connection

    WHILE WAIT(connection, 50)
        RECEIVE data$ FROM connection
        IF LEN(data$) = 0 THEN BREAK
        response$ = response$ & data$
    WEND

    IF use_pasv THEN
        WHILE WAIT(passive, 50)
            RECEIVE data$ FROM passive
            IF LEN(data$) = 0 THEN BREAK
            response$ = response$ & data$
        WEND
        CLOSE NETWORK passive
    ENDIF

    RETURN response$

ENDFUNC

OPEN "localhost:21" FOR NETWORK AS ftp

PRINT interact$("", ftp, 0)
PRINT interact$("USER anonymous", ftp, 0)
PRINT interact$("PASS ", ftp, 0)
PRINT interact$("CWD pub", ftp, 0)
PRINT interact$("LIST", ftp, 1)
PRINT interact$("TYPE I", ftp, 0)
PRINT interact$("RETR data.txt", ftp, 1)
PRINT interact$("QUIT", ftp, 0)

CLOSE NETWORK ftp