求助：vsftpd启动报错code=exited, status=2

vsftpd版本：vsftpd-3.0.2-22.el7.x86_64

centos7:CentOS Linux release 7.4.1708 (Core)

vsftpd配置文件如下：

anonymous_enable=NO

anon_root=/var/ftp

local_enable=YES

local_root=/home/fangliang

write_enable=YES

local_umask=022

use_localtime=YES

ftpd_banner=Welcome to fangzhou FTP Server

chroot_local_user=NO

chroot_list_enable=YES

chroot_list_file=/etc/vsftpd/chroot_black

xferlog_enable=YES

#日志保存为标准格式

xferlog_std_format=YES

#指定FTP使用20端口进行数据传输

connect_from_port_20=YES

pasv_enable=YES

pasv_min_port=61001

pasv_max_port=62000

listen=YES

pam_service_name=/etc/pam.d/vsftpd

guest_enable= YES

guest_username=fangliang

user_config_dir=/etc/vsftpd/usersconf

allow_writeable_chroot=YES

listen_ipv6=NO

错误信息：

查看状态：systemctl status vsftpd.service

[root@localhost ~]# systemctl status vsftpd.service

● vsftpd.service - Vsftpd ftp daemon
   Loaded: loaded (/usr/lib/systemd/system/vsftpd.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Tue 2018-04-24 00:54:04 CST; 10s ago
  Process: 6112 ExecStart=/usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf (code=exited, status=2)
 Main PID: 973 (code=killed, signal=TERM)

Apr 24 00:54:04 localhost.localdomain systemd[1]: Starting Vsftpd ftp daemon...
Apr 24 00:54:04 localhost.localdomain systemd[1]: vsftpd.service: control process exited, code=exited status=2
Apr 24 00:54:04 localhost.localdomain systemd[1]: Failed to start Vsftpd ftp daemon.
Apr 24 00:54:04 localhost.localdomain systemd[1]: Unit vsftpd.service entered failed state.

Apr 24 00:54:04 localhost.localdomain systemd[1]: vsftpd.service failed.

执行journalctl -xe：

[root@localhost ~]# journalctl -xe
Apr 24 00:46:44 localhost.localdomain polkitd[587]: Registered Authentication Agent for unix-process:5997:1727711 (system bus name :1.178 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
Apr 24 00:46:44 localhost.localdomain systemd[1]: Starting Vsftpd ftp daemon...
-- Subject: Unit vsftpd.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit vsftpd.service has begun starting up.
Apr 24 00:46:44 localhost.localdomain systemd[1]: vsftpd.service: control process exited, code=exited status=2
Apr 24 00:46:44 localhost.localdomain systemd[1]: Failed to start Vsftpd ftp daemon.
-- Subject: Unit vsftpd.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit vsftpd.service has failed.
--
-- The result is failed.
Apr 24 00:46:44 localhost.localdomain systemd[1]: Unit vsftpd.service entered failed state.
Apr 24 00:46:44 localhost.localdomain systemd[1]: vsftpd.service failed.
Apr 24 00:46:44 localhost.localdomain polkitd[587]: Unregistered Authentication Agent for unix-process:5997:1727711 (system bus name :1.178, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
Apr 24 00:50:01 localhost.localdomain systemd[1]: Started Session 38 of user root.
-- Subject: Unit session-38.scope has finished start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit session-38.scope has finished starting up.
--
-- The start-up result is done.
Apr 24 00:50:01 localhost.localdomain systemd[1]: Starting Session 38 of user root.
-- Subject: Unit session-38.scope has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit session-38.scope has begun starting up.
Apr 24 00:50:01 localhost.localdomain CROND[6052]: (root) CMD (/usr/lib64/sa/sa1 1 1)
Apr 24 00:54:04 localhost.localdomain polkitd[587]: Registered Authentication Agent for unix-process:6106:1771659 (system bus name :1.181 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
Apr 24 00:54:04 localhost.localdomain systemd[1]: Starting Vsftpd ftp daemon...
-- Subject: Unit vsftpd.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit vsftpd.service has begun starting up.
Apr 24 00:54:04 localhost.localdomain systemd[1]: vsftpd.service: control process exited, code=exited status=2
Apr 24 00:54:04 localhost.localdomain systemd[1]: Failed to start Vsftpd ftp daemon.
-- Subject: Unit vsftpd.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit vsftpd.service has failed.
--
-- The result is failed.
Apr 24 00:54:04 localhost.localdomain systemd[1]: Unit vsftpd.service entered failed state.
Apr 24 00:54:04 localhost.localdomain systemd[1]: vsftpd.service failed.
Apr 24 00:54:04 localhost.localdomain polkitd[587]: Unregistered Authentication Agent for unix-process:6106:1771659 (system bus name :1.181, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)

求救，求救！！！！！！