map to guest = Bad User
ntlm auth = yes
veto files = /.*/
后来各种研究折腾，在Samba 4.6.2的更新日志里找到：
To improve security, the NT LAN manager version 1 (NTLMv1) protocol is now disabled by default. If you require the insecure NTLMv1 protocol, set the ntlm auth parameter in the /etc/samba/smb.conf file to yes.
大意就是为了提高安全性，从4.6.2版本开始NTLMv1协议默认是关闭状态的，需要手动配置开启。
编辑 /etc/samba/smb.conf，在Global项下添加 ntlm auth = yes 参数
[root@eugbd-lapp0213 conf]# systemctl restart smb
Failed to restart smb.service: Unit not found.
[root@eugbd-lapp0213 conf]# yum install samba