刚刚在 Ubuntu Server 上安装了带有 proftpd 的 Webmin，现在我可以连接到服务器并使用我的 ftp 用户名和密码登录，但是当我尝试传输文件时，小文件可以轻松上传，但大文件会卡住并超时。甚至 200 KB 的图像也无法上传。
这里是我的 proftpd 的配置文件：
#
# /etc/proftpd/proftpd.conf -- This is a basic ProFTPD configuration file.
# To really apply changes, reload proftpd after modifications, if
# it runs in daemon mode. It is not required in inetd/xinetd mode.
#
# 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 "Debian"
ServerType standalone
DeferWelcome off
MultilineRFC2228 on
DefaultServer on
ShowSymlinks on
TimeoutNoTransfer 600
TimeoutStalled 600
TimeoutIdle 1200
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
# Logging onto /var/log/lastlog is enabled but set to off by default
#UseLastlog on
# In order to keep log file dates consistent after chroot, use timezone info
# from /etc/localtime. If this is not set, and proftpd is configured to
# chroot (e.g. DefaultRoot or <Anonymous>), it will use the non-daylight
# savings timezone regardless of whether DST is in effect.
#SetEnv TZ :/etc/localtime
<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
# http://www.securityfocus.com/bid/11430/discuss
# It is on by default.
<IfModule mod_delay.c>
DelayEngine on
</IfModule>
<IfModule mod_ctrls.c>
ControlsEngine off
ControlsMaxClients 2
ControlsLog /var/log/proftpd/controls.log
ControlsInterval 5
ControlsSocket /var/run/proftpd/proftpd.sock
</IfModule>
<IfModule mod_ctrls_admin.c>
AdminControlsEngine off
</IfModule>
#
# Alternative authentication frameworks
#
#Include /etc/proftpd/ldap.conf
#Include /etc/proftpd/sql.conf
#
# This is used for FTPS connections
#
#Include /etc/proftpd/tls.conf
#
# Useful to keep VirtualHost/VirtualRoot directives separated
#
#Include /etc/proftpd/virtuals.con
# A basic anonymous configuration, no upload directories.
# <Anonymous ~ftp>
# User ftp
# Group nogroup
# # We want clients to be able to login with "anonymous" as well as "ftp"
# UserAlias anonymous ftp
# # Cosmetic changes, all files belongs to ftp user
# DirFakeUser on ftp
# DirFakeGroup on ftp
#
# RequireValidShell off
#
# # Limit the maximum number of anonymous logins
# MaxClients 10
#
# # We want 'welcome.msg' displayed at login, and '.message' displayed
# # in each newly chdired directory.
# DisplayLogin welcome.msg
# DisplayChdir .message
#
# # Limit WRITE everywhere in the anonymous chroot
# <Directory *>
# <Limit WRITE>
# DenyAll
# </Limit>
# </Directory>
#
# # Uncomment this if you're brave.
# # <Directory incoming>
# # # Umask 022 is a good standard umask to prevent new files and dirs
# # # (second parm) from being group and world writable.
# # Umask 022 022
# # <Limit READ WRITE>
# # DenyAll
# # </Limit>
# # <Limit STOR>
# # AllowAll
# # </Limit>
# # </Directory>
#
# </Anonymous>
# Include other custom configuration files
Include /etc/proftpd/conf.d/
以下是日志文件内容：
Aug 01 12:58:43 liXXX-XXX proftpd[6039] liXXX-XXX.members.linode.com (IP[IP]): FTP session opened.
... USER MYUSER: Login successful.
... notice: user MYUSER: aborting transfer: Link to file server lost
... FTP session closed.
...: FTP session opened.
...: USER MYUSER: Login successful.
... notice: user MYUSER: aborting transfer: Link to file server lost
...: FTP session closed.
...: FTP session opened.
...
答案1
事实证明这是一个防火墙问题，运行以下命令关闭了防火墙，它对我来说有效。
sudo ufw disable
sudo iptables -F
希望它能对任何寻求解决方案的人有所帮助。