I send you the diff file. All that I did was to comment a few lines. I'm not
sure at all that it works or that I did would be an aberration, but it let
me make a ftps implicit connection with the filezilla server. The following
text is the diff file:

2587c2587

< //if(!conn->ssl[SECONDARYSOCKET].use) {

---
> if(!conn->ssl[SECONDARYSOCKET].use) {
2591c2591
< /*}
---
> }
2596c2596
< }*/
---
> }
As you can see all that I did was to comment a few lines to send a PROT
always that a PBSZ was sended. I think that this change is very riskful, but
I want to know your opinion.
I paste the full "switch case" where I make the change to help you to find
the block of the code:
case FTP_PBSZ:
/* FIX: check response code */
/* For TLS, the data connection can have one of two security levels.
1) Clear (requested by 'PROT C')
2)Private (requested by 'PROT P')
*/
//if(!conn->ssl[SECONDARYSOCKET].use) {
NBFTPSENDF(conn, "PROT %c",
data->set.ftp_ssl == CURLFTPSSL_CONTROL ? 'C' : 'P');
state(conn, FTP_PROT);
/*}
else {
result = ftp_state_pwd(conn);
if(result)
return result;
}*/
break;
That is at the ftp_statemach_act function of the ftp.c file.
Best regards,
Abel.