16 May 2013 17:17
[Proftpd-user] SFTP hung sessions and error "Server unexpectedly closed network connection" for only one user
Ezsra McDonald <ezsra.mcdonald <at> gmail.com>
2013-05-16 15:17:10 GMT
2013-05-16 15:17:10 GMT
Greetings,
We have 100's of Core_FTP clients that access our FTP server on SFTP port 2222. For some reason one of them is consistently leaving sessions open and the server is not killing them.
Customer is reporting the following message:
"Server unexpectedly closed network connection"
"Server unexpectedly closed network connection"
This is how the user sessions look from a ftpwho query:
ftphost:~$ ftpwho
standalone FTP daemon [29724], up for 4 days, 10 hrs 26 min
17010 theUser [ 50h2m] (n/a) READDIR /
14165 theUser [25h55m] (n/a) READDIR /
23548 theUser [22h17m] (n/a) LIST
23186 theUser [22h25m] (n/a) READDIR /
24414 theUser [21h57m] (n/a) READDIR /
23224 theUser [22h24m] (n/a) LIST
23251 theUser [22h23m] (n/a) LIST
23444 theUser [22h19m] (n/a) LIST
We have to restart the server for the user to regain access.
TimeoutIdle 800
TimeoutLogin 300
TimeoutNoTransfer 800
Any suggestions?
--Ezsra
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On a debian server I've proftpd-basic 1.3.3a.
Runs perfectly if I use it without TLS.
When I enable TLS, my clients goes to time out:
Command: MLSD
Error: Connection timed out
Error: Failed to retrieve directory listing
Half or more aftertoon to search with google but I didn't find any
solution 
((
thanks for the help!
tail -f /var/log/proftpd/tls.log
May 15 17:58:38 mod_tls/2.4.2[20385]: using default OpenSSL verification
locations (see $SSL_CERT_DIR environment variable)
May 15 17:58:38 mod_tls/2.4.2[20385]: TLS/TLS-C requested, starting TLS
handshake
May 15 17:58:38 mod_tls/2.4.2[20385]: TLSv1/SSLv3 connection accepted,
using cipher DHE-RSA-AES128-SHA (128 bits)
May 15 17:58:38 mod_tls/2.4.2[20385]: Protection set to Private
My config:
openssl req -new -x509 -days 365 -nodes -out
/etc/proftpd/ssl/proftpd.cert.pem -keyout /etc/proftpd/ssl/proftpd.key.pem
tls.conf
<IfModule mod_tls.c>
TLSEngine on
TLSLog /var/log/proftpd/tls.log
TLSProtocol SSLv23
TLSOptions NoCertRequest
TLSRSACertificateFile /etc/proftpd/ssl/proftpd.cert.pem
TLSRSACertificateKeyFile /etc/proftpd/ssl/proftpd.key.pem
TLSVerifyClient off
TLSRequired on
</IfModule>
and proftpd.conf
# Includes DSO modules
Include /etc/proftpd/modules.conf
# Set off to disable IPv6 support which is annoying on IPv4 only boxes.
UseIPv6 on
# If set on you can experience a longer connection delay in many cases.
IdentLookups off
ServerName "fuckaround.org"
ServerType standalone
DeferWelcome off
MultilineRFC2228 on
DefaultServer on
ShowSymlinks on
TimeoutNoTransfer 1200
TimeoutStalled 1200
TimeoutIdle 1600
DisplayLogin welcome.msg
DisplayChdir .message true
ListOptions "-l"
DenyFilter \*.*/
# Use this to jail all users in their homes
DefaultRoot ~
# Users require a valid shell listed in /etc/shells to login.
# Use this directive to release that constrain.
# RequireValidShell off
# Port 21 is the standard FTP port.
Port 21
# In some cases you have to specify passive ports range to by-pass
# firewall limitations. Ephemeral ports can be used for that, but
# feel free to use a more narrow range.
PassivePorts 49152 65534
# If your host was NATted, this option is useful in order to
# allow passive tranfers to work. You have to use your public
# address and opening the passive ports used on your firewall as well.
# MasqueradeAddress 1.2.3.4
# This is useful for masquerading address with dynamic IPs:
# refresh any configured MasqueradeAddress directives every 8 hours
<IfModule mod_dynmasq.c>
# DynMasqRefresh 28800
</IfModule>
# To prevent DoS attacks, set the maximum number of child processes
# to 30. If you need to allow more than 30 concurrent connections
# at once, simply increase this value. Note that this ONLY works
# in standalone mode, in inetd mode you should use an inetd server
# that allows you to limit maximum number of processes per service
# (such as xinetd)
MaxInstances 30
# Set the user and group that the server normally runs at.
User proftpd
Group nogroup
# Umask 022 is a good standard umask to prevent new files and dirs
# (second parm) from being group and world writable.
Umask 022 022
# Normally, we want files to be overwriteable.
AllowOverwrite on
# Uncomment this if you are using NIS or LDAP via NSS to retrieve passwords:
# PersistentPasswd off
# This is required to use both PAM-based authentication and local passwords
# AuthOrder mod_auth_pam.c* mod_auth_unix.c
# Be warned: use of this directive impacts CPU average load!
# Uncomment this if you like to see progress and transfer rate with ftpwho
# in downloads. That is not needed for uploads rates.
#
# UseSendFile off
TransferLog /var/log/proftpd/xferlog
SystemLog /var/log/proftpd/proftpd.log
<IfModule mod_quotatab.c>
QuotaEngine off
</IfModule>
<IfModule mod_ratio.c>
Ratios off
</IfModule>
# Delay engine reduces impact of the so-called Timing Attack described in
# 
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