access denied by server while mounting (server denied access during installation) solution

The first step is to check whether the software rpcbind and nfs-utils are installed

[root@li wode]# yum info rpcbind
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
已安装的软件包
名称    ：rpcbind
架构    ：x86_64
版本    ：0.2.0
......                  //省略部分信息
[root@li wode]# yum info nfs-utils
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
已安装的软件包
名称    ：nfs-utils
架构    ：x86_64
时期       ：1
版本    ：1.3.0
......                  //省略部分信息

In the second part, use showmount -e to see if you can see the NFS service on the server

[root@wu opt]# showmount -e 20.0.0.15  //查看NFS共享目录
Export list for 20.0.0.15:   
/opt/wode 20.0.0.0/24  //服务器端NFS共享的目录

The third part is to check whether the NFS service on the server side is enabled, and check whether the configuration file is wrong

[root@li wode]# systemctl restart nfs    //重启NFS服务
[root@li wode]# vi /etc/exports          //查看NFS的配置文件
/opt/woede 20.0.0.0/24(rw,sync,no_root_squash)  //允许20.0.0网段的可以查看NFS共享目录
  //我的问题就出现在这里，我发布的是/opt/wode，而我的配置文件中是/opt/woede多了个e导致我客户端在挂载的时候总是出现报错。
[root@li wode]# vi /etc/exports
/opt/wode 20.0.0.0/24(rw,sync,no_root_squash)   //修改后


1、修改前挂载情况
[root@wu opt]# mount 20.0.0.16:/opt/wode /var/tade
mount.nfs: access denied by server while mounting 20.0.0.16:/opt/wode   //报错

2、修改后挂载情况
[root@wu opt]# mount 20.0.0.16:/opt/wode /var/tade
[root@wu opt]# df -Th
文件系统                类型      容量  已用  可用 已用% 挂载点
/dev/mapper/centos-root xfs        17G  5.2G   12G   31% /
devtmpfs                devtmpfs  1.9G     0  1.9G    0% /dev
tmpfs                   tmpfs     1.9G     0  1.9G    0% /dev/shm
tmpfs                   tmpfs     1.9G  8.6M  1.9G    1% /run
tmpfs                   tmpfs     1.9G     0  1.9G    0% /sys/fs/cgroup
/dev/sr0                iso9660   4.3G  4.3G     0  100% /mnt
/dev/sda1               xfs      1014M  143M  872M   15% /boot
tmpfs                   tmpfs     378M     0  378M    0% /run/user/0
20.0.0.16:/opt/wode     nfs4       17G 1006M   17G    6% /var/tade          //挂载成功

Other reasons for error

1. An illegal port is used, that is, a port greater than 1024 is used.

This error can be confirmed by viewing the log:
[root@local~ /]# cat /var/log/messages | grep mount
Jan 2 12:49:04 localhost mountd[1644]: refused mount request from 192.168.0.100 for /home /nfsshare/ (/home/nfsshare): illegal port 1689

Solution:
Modify the configuration file /etc/exports, add the insecure option, restart the nfs service, and try to mount it again.
/home/nfsshare/ *(insecure,rw,async,no_root_squash)

2. NFS version issue

Edit the /etc/sysconfig/nfs file and find the following:

#Turn off v2 and v3 protocol support 
#RPCNFSDARGS="-N 2 -N 3" 
#Turn off v4 protocol support 
#RPCNFSDARGS="-N 4"　　/*把这句前面的#号去掉*/

Finally save, restart the nfs service, and try to mount again; if it fails to mount, try adding the -o nolock parameter afterwards.

When the client mounts the NFS service, an error occurs mount.nfs: access denied by server while mounting (server denied access during installation) solution