Frequently gets stuck on directory listings if using SSL/TLS

It frequently gets stuck on listing directories if I use SSL/TLS. If I reconnect without, it's always fine.
I've tested with 4.2.4 build 1794 and 4.2.4 build 1785.

[14:36:04] [R] 227 Entering Passive Mode (176,xx,xx,xx,215,217).
[14:36:04] [R] Opening data connection IP: 176.xx.xx.xx PORT: 55257
[14:36:04] [R] LIST -al
[14:36:04] [R] Connected. Negotiating SSL/TLS session
[14:36:04] [R] SSLv3 negotiation successful...
[14:36:04] [R] SSLv3 encrypted session using cipher AES256-SHA (256 bits)
[14:36:04] [R] 150 Here comes the directory listing.

It just sits there until it times out. I've tried other clients and it doesn't happen with them.

Do you know what FTP server software is being used?

Sometimes these type of issues can be difficult to resolve when we're unable to reproduce the exact behavior.

It's running vsftpd 2.3.5.

I setup vsftpd v2.3.5 but I am not able to reproduce the problem.

Would it be possible to create a test account for me? If so please send me a private message with the server and account information.

If that's not possible can you please provide me with a copy of the vsftpd.conf

# Example config file /etc/vsftpd.conf
#
# The default compiled in settings are fairly paranoid. This sample file
# loosens things up a bit, to make the ftp daemon more usable.
# Please see vsftpd.conf.5 for all compiled in defaults.
#
# READ THIS: This example file is NOT an exhaustive list of vsftpd options.
# Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's
# capabilities.
#
#
# Run standalone?  vsftpd can run either from an inetd or as a standalone
# daemon started from an initscript.
listen=YES
#
# Run standalone with IPv6?
# Like the listen parameter, except vsftpd will listen on an IPv6 socket
# instead of an IPv4 one. This parameter and the listen parameter are mutually
# exclusive.
#listen_ipv6=YES
#
# Allow anonymous FTP? (Disabled by default)
anonymous_enable=NO
#
# Uncomment this to allow local users to log in.
local_enable=YES
#
# Uncomment this to enable any form of FTP write command.
write_enable=YES
#
# Default umask for local users is 077. You may wish to change this to 022,
# if your users expect that (022 is used by most other ftpd's)
local_umask=022
#
# Uncomment this to allow the anonymous FTP user to upload files. This only
# has an effect if the above global write enable is activated. Also, you will
# obviously need to create a directory writable by the FTP user.
#anon_upload_enable=YES
#
# Uncomment this if you want the anonymous FTP user to be able to create
# new directories.
#anon_mkdir_write_enable=YES
#
# Activate directory messages - messages given to remote users when they
# go into a certain directory.
dirmessage_enable=YES
#
# If enabled, vsftpd will display directory listings with the time
# in  your  local  time  zone.  The default is to display GMT. The
# times returned by the MDTM FTP command are also affected by this
# option.
use_localtime=YES
#
# Activate logging of uploads/downloads.
xferlog_enable=YES
#
# Make sure PORT transfer connections originate from port 20 (ftp-data).
connect_from_port_20=YES
#
# If you want, you can arrange for uploaded anonymous files to be owned by
# a different user. Note! Using "root" for uploaded files is not
# recommended!
#chown_uploads=YES
#chown_username=whoever
#
# You may override where the log file goes if you like. The default is shown
# below.
#xferlog_file=/var/log/vsftpd.log
#
# If you want, you can have your log file in standard ftpd xferlog format.
# Note that the default log file location is /var/log/xferlog in this case.
#xferlog_std_format=YES
#
# You may change the default value for timing out an idle session.
#idle_session_timeout=600
#
# You may change the default value for timing out a data connection.
#data_connection_timeout=120
#
# It is recommended that you define on your system a unique user which the
# ftp server can use as a totally isolated and unprivileged user.
#nopriv_user=ftpsecure
#
# Enable this and the server will recognise asynchronous ABOR requests. Not
# recommended for security (the code is non-trivial). Not enabling it,
# however, may confuse older FTP clients.
#async_abor_enable=YES
#
# By default the server will pretend to allow ASCII mode but in fact ignore
# the request. Turn on the below options to have the server actually do ASCII
# mangling on files when in ASCII mode.
# Beware that on some FTP servers, ASCII support allows a denial of service
# attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd
# predicted this attack and has always been safe, reporting the size of the
# raw file.
# ASCII mangling is a horrible feature of the protocol.
#ascii_upload_enable=YES
#ascii_download_enable=YES
#
# You may fully customise the login banner string:
#ftpd_banner=Welcome to blah FTP service.
#
# You may specify a file of disallowed anonymous e-mail addresses. Apparently
# useful for combatting certain DoS attacks.
#deny_email_enable=YES
# (default follows)
#banned_email_file=/etc/vsftpd.banned_emails
#
# You may restrict local users to their home directories.  See the FAQ for
# the possible risks in this before using chroot_local_user or
# chroot_list_enable below.
#chroot_local_user=YES
#
# You may specify an explicit list of local users to chroot() to their home
# directory. If chroot_local_user is YES, then this list becomes a list of
# users to NOT chroot().
#chroot_local_user=YES
chroot_list_enable=YES
## (default follows)
chroot_list_file=/etc/vsftpd.chroot_list
#
# You may activate the "-R" option to the builtin ls. This is disabled by
# default to avoid remote users being able to cause excessive I/O on large
# sites. However, some broken FTP clients such as "ncftp" and "mirror" assume
# the presence of the "-R" option, so there is a strong case for enabling it.
#ls_recurse_enable=YES
#
# Debian customization
#
# Some of vsftpd's settings don't fit the Debian filesystem layout by
# default.  These settings are more Debian-friendly.
#
# This option should be the name of a directory which is empty.  Also, the
# directory should not be writable by the ftp user. This directory is used
# as a secure chroot() jail at times vsftpd does not require filesystem
# access.
secure_chroot_dir=/var/run/vsftpd/empty
#
# This string is the name of the PAM service vsftpd will use.
pam_service_name=vsftpd
#
# This option specifies the location of the RSA certificate to use for SSL
# encrypted connections.
#rsa_cert_file=/etc/ssl/private/vsftpd.pem


rsa_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
rsa_private_key_file=/etc/ssl/private/ssl-cert-snakeoil.key

ssl_enable=YES
ssl_tlsv1=YES
ssl_sslv2=YES
ssl_sslv3=YES
force_local_logins_ssl=NO
force_local_data_ssl=NO

require_ssl_reuse=NO

max_per_ip=15

ssl_ciphers=HIGH

I am running with your vsftpd configuration for about an hour and I have not been able to reproduce the problem, I will continue for a few more hours and let you know what I find if anything.

I am afraid I can't reproduce the problem using your configuration.

Perhaps the issue is specific to the linux distro or the way vsftpd was compiled, any way you can create a test account for me?

Odd. I consistently get it using a several systems but only with FlashFXP using SSL/TLS. FileZilla is fine (although an awful client). Unfortunately, test account isn't possible. I've just tested again, still can't list directories most of the time with SSL/TLS, but reconnecting without always works. May have been a slight incompatibility, I've just updated vsftpd to 3.0 and so far it seems fine. I'll update in a few days.

Nope, still happens. But only with FlashFXP and SSL/TLS. FileZilla is still fine.

* Edit:
Seems to only happen using TLSv1, if I switch to SSLv3 it's fine. FileZilla is also using TLSv1 and it doesn't have problems listing directories. FileZilla is also using TLSv1 and has no problems with transfers/listings getting stuck.

Based on your new information it could be a compatibility issue between the OpenSSL version used by FlashFXP and the OpenSSL version used by the server.

You could try using different versions of OpenSSL, such as 1.0.0j, or 0.9.8x. We do not offer, or support them, or perhaps try the OpenSSL dlls from a previous version of FlashFXP that worked and try it with the current version.

Upgrading FlashFXP will automatically install the latest version of OpenSSL, so you'll need to keep a backup somewhere so you can replace them after any updates.

Its difficult to diagnose and pin-point these types of issues without actual access to the problematic server as there are so many different variables that come into play.

I'm afraid there's not much more I can do to resolve this issue without having a way to reproduce the issue.

Just given FlashFXP the same libraries vsftpd is using, still gets stuck all the time. Only happens with FlashFXP and non-local servers.
I still have no issues with FileZilla (GnuTLS), WinSCP (OpenSSL 1.0.1c), SmartFTP (OpenSSL 1.1.0) or Android FTP clients (AndFTP, cafeFTP).

I sent you a private message, have you had a chance to read it yet?

Ive tested download/upload with a FlashFXP Test server VSFTPD 3.0.0 and FlashFXP 4.2.6 build 1834, using TLSv1 and the default ssl binaries provided. I accepted the encryption key ONLY ONCE-meaning it would prompt to accept key eac h time I connected/reconnected to this server.

No failures at all during neither download/upload. Test Files were completely uploaded/downloaded)

here are my logs http://pastebin.com/K2SHaETR

Only thing I noticed was at the very end of the upload the connection to server stopped at 100% for a while seemed like 10/15secs and was restarted (I got prompted to accept the key again, so it means it must have been lost at some stage at the very end.

Its all in the logs.