I've been noticing that the passive data connections are taking quite
some time when using SSL. I finally got some time to look into this
and noticed the following while debugging through the code. This issue
might have been introduced with the fix we put in for FTPSERVER-241.

The code that wraps the plain socket into an SSL socket uses the
following line:

                    SSLSocket sslSocket = (SSLSocket) ssocketFactory
                                    serverSocket.getPort(), true);

Based on the JavaDocs, the InetAddress.getHostName() performs a
reverse name look up, which was taking about 1.5 seconds on every
system on our network. I'm not sure if this is an issue with the way
our network is setup. Some one please let me know if this in fact an
issue with our network.

We are not seeing this lag when client and server are running on the
same system. Things work too fast in this case, probably because the
system knows very well about itself.

Just to try it out, I changed the code to simply use the IP address
rather than the host name, and I was able to get rid of the lag and
things seem to be working much faster. Below is the change to the
above line:

                    SSLSocket sslSocket = (SSLSocket) ssocketFactory
                                    serverSocket.getPort(), true);

Could some one test the current code base with client and server
running on different systems and tell me if they notice the lag when
creating the passive data connection. If this can be reproduced on one
of your environments, we should probably put the above fix. I don't
think this suggested fix should cause any other issues, do you?


Sai Pullabhotla

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