I have an FTP server that uses IIS 7.5, running on a Windows Server 2008 machine. When I try to connect to this server using filezilla with implicit TLS (ftps://), I always recieve this error:

GnuTLS error -15: An unexpected TLS packet was received.

The server connects fine when I don't use TLS (ftp://) or with explicit TLS (ftpes://) so I believe it is not a SSL issue.

Am I missing a configuration here?

Update: I was trying to connect to ftps using port 2122.


1 Answer 1


Ensure that you have a binding for port 990, as that is the implicit FTPS port. Without that binding your site in IIS will not support implicit FTPS.

  • By binding, do you mean to open port 990 in firewalls? Nov 20, 2014 at 1:10
  • @SyakurRahman No, I mean a binding on the FTP site in IIS. Sites (web or FTP) in IIS operate based on bindings, a combination of IP, port, protocol, and sometimes host header name that define which sites answer to which requests.
    – phoebus
    Nov 20, 2014 at 1:13
  • @SyakurRahman Here's an example of a port 21 binding: 4.bp.blogspot.com/-gByQR4TlBfw/UGs3h7yRuaI/AAAAAAAAMNY/…
    – phoebus
    Nov 20, 2014 at 1:14
  • Okay, it did worked :). The previous test I did was using a custom port which is 2122. I already have a binding to that port, is there something else I need to configure so I could use port 2122 with ftps? Nov 20, 2014 at 1:16
  • 1
    You can use port 2122 with explicit FTPS assuming you connect to that port on your client. Implicit FTPS can only be used with port 990.
    – phoebus
    Nov 20, 2014 at 1:17

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