Opened 19 years ago

Last modified 10 years ago

#844 closed Bug report

Failure to establish TLS connection behind NAT gateway

Reported by: peter_daum Owned by: Alexander Schuch
Priority: normal Component: FileZilla Client
Keywords: Cc: peter_daum, Alexander Schuch, easiconseil, mortemorte
Component version: Operating system type:
Operating system version:


FileZilla (2.2.12c) can't establish a TLS connection to
a PureFTPd
server (possibliy other servers, too?) when it (the
FileZilla client)
is sitting behind a NAT gateway.
The problem already arises during the TLS connection
(so this is _not_ a "classical" firewall issue with
tracking the data connections!).

The conversation looks like this:

  • Client connects to server
  • Server responds with ready
  • Client sends "AUTH TLS"
  • Server responds with OK
  • Client sends some (scrambled) request
  • Server responds with (scrambled) response (obviously OK,

since there is no indication of any failure in the log)

  • Both parties wait for something that doesn't happen
  • ... eventually, FileZilla times out and starts all

over again
The connection does not get to the point, where the TLS
for the control channel is succesfully established
(this would show
up in the log files)

Whe the FileZilla client has a "real" IP address, it
can cooperate with
the same server. Other clients (I tested "lftp") have
no problem to
establish the TLS connection through the NAT gateway.

Attached is a packet dump of the network traffic (
which due to the
encryption is not really enlightening)

Attachments (1)

capture.txt (6.4 KB ) - added by peter_daum 19 years ago.
captured network traffic

Download all attachments as: .zip

Change History (5)

by peter_daum, 19 years ago

Attachment: capture.txt added

captured network traffic

comment:1 by easiconseil, 19 years ago

I make tests and the bug occure with Titan FTP Server v3 and
v4 and BlackMoon FTP Server v3.0.4.1723.

I use FileZilla 2.2.12c behind a Bewan Booster 32g router.

comment:2 by mortemorte, 19 years ago

I confirm this issuse with a Serv-U ftp version 5 and 6.
Old filezilla 2.2.11 works.

comment:3 by Alexander Schuch, 16 years ago

As this bug report is quite old and lots has changed in the client... please try latest FileZilla 3 and check if it works there. And please report back so that the bug can be fixed in case it still is there.

comment:4 by sf-robot, 16 years ago

This Tracker item was closed automatically by the system. It was
previously set to a Pending status, and the original submitter
did not respond within 14 days (the time period specified by
the administrator of this Tracker).

Note: See TracTickets for help on using tickets.