lftp file transfer in shell script

script uses conf file as an input:

[mandy@mandy mpix]$ cat lftp.sh 
#!/bin/sh
lftp -f lftp.conf

Input file uses open command on port 2121:

[mandy@mandy mpix]$ cat lftp.conf 
open -p 2121 server_name
mput file1
mput file2
mput file3
bye