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Newsgroups: mail-lists.delegate-en

[DeleGate-En] Antwort: Re: [DeleGate-En] FileZilla TLS security patch does not work with F TPS and Delegate
19 Aug 2008 10:37:20 GMT

Hi Yutaka,
The patch you provided in fact solves the problem. It works fine again.
Thank you very much.

 Markus (Yutaka Sato) wrote on 19.08.2008 10:34:37:

> Hi,
> In message <OF8F417BBA.3A21C746-ONC12574AA.0027F3C4-C12574AA.
>> on 08/19/08(16:35:30)
> you wrote:
>  |We are using DeleGate as a ftp to ftps proxy. The setting used to work
>  |*very well* (and therefore a big thank you for the author
>  |of DeleGate). The problem is with Explicit and Implicit SSL/TLS. With 
>  |older version (3.0.11, which is before FileZilla security patch) 
>  |and DeleGate work like a charm.With new versions of FileZilla there is 
>  |problem however, which seems to be related to below issue (the snippet 
>  |from the FileZilla project's website
>  |
>  |
>  |2008-07-24 - Security Advisory
>  |FileZilla fixes a vulnerability regarding the way some errors 
>  |handled on SSL/TLS secured data transfers.
>  |If the data connection of a transfer gets closed, FileZilla did not 
>  |if the server performed an orderly TLS shutdown.
>  |Impact
>  |An attacker could send spoofed FIN packets to the client. Even though
>  |GnuTLS detects this with GNUTLS_E_UNEXPECTED_PACKET_LENGTH, FileZilla 
>  |not record a transfer failure in all cases.
>  |Unfortunately not all servers perform an orderly SSL/TLS shutdown. 
>  |this cannot be distinguished from an attack, FileZilla will not be 
able to
>  |download listings or files from such servers.
>  |Affected versions
>  |All versions prior to are affected. This vulnerability has 
>  |fixed in
>  |
>  |The error returned by FileZilla points to the issue addressed in the
>  |Security Advisory. The german text means
>  |"Server did not shutdown TLS-Connection properly."
> ...
>  |I am not sure whether this is an issue with SSLway or with DeleGate. 
>  |there a workaround for the described problem?
>  |I would apprieciate your answer and again, I think you do a great job!
> ...
>  |09:15:43        Trace:  CTlsSocket::OnRead()
>  |09:15:43        Trace:  CTlsSocket::OnSocketEvent(): close event 
>  |09:15:43        Trace:  CTransferSocket::OnReceive(), m_transferMode=0
>  |09:15:43        Trace:  GnuTLS error -9: A TLS packet with unexpected
>  |length was received.
>  |09:15:43        Status: Server hat die TLS-Verbindung nicht 
>  |geschlossen
>  |09:15:43        Fehler: Could not read from transfer socket: 
> This seems the same problem I heard last night...
> If so, you might be able to solve it with the patch I postedn in:
> <URL:>
> And more detailed log output about SSL handling in DeleGate with
> "TLSCONF=-vd" option will be helpful to see what is going.
> Cheers,
> Yutaka
> --
>   9 9   Yutaka Sato <>
>  ( ~ )  National Institute of Advanced Industrial Science and Technology
> _<   >_ 1-1-4 Umezono, Tsukuba, Ibaraki, 305-8568 Japan
> Do the more with the less -- B. Fuller

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