背景：
进行nfs实验时，发现nfs 挂载时使用mount -a 失败，提示如下信息
mount.nfs: access denied by server while mounting system1.domain1.example.com:/product

步骤：
1、查看nfs-server日志
tail -f /var/log/messages 没有任何提示
/var/log/路径下也无任何相关日志

2、查看服务器端firewalld 配置
一切正常

3、检查client 网络连接
没有发现异常

[root@node2 ~]# netstat -antu
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:111 0.0.0.0: LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0: LISTEN
tcp 0 0 x.x.x.x:819 x.x.x.x:2049 TIME_WAIT
tcp 0 0 x.x.x.x:25782 x.x.x.x:4505 ESTABLISHED
tcp 0 52 x.x.x.x:22 x.x.x.x:62480 ESTABLISHED
udp 0 0 127.0.0.1:323 0.0.0.0:*
[root@node2 ~]#
[root@node2 ~]#
[root@node2 ~]#

4、nfs-server抓包
发现明显报错信息
18:56:32.264938 IP node1.example.com.nfs > node2.example.com.945: Flags [P.], seq 29:53, ack 237, win 59, options [nop,nop,TS val 14292395 ecr 633061586], length 24: NFS reply xid 1460849323 reply ERR 20: Auth Bogus Credentials (seal broken)
18:56:32.264984 IP node2.example.com.945 > node1.example.com.nfs: Flags [F.], seq 237, ack 53, win 58, options [nop,nop,TS val 633061586 ecr 14292395], length 0
5、google
发现有类似错误，原因为nfs-utils bug导致，通过
yum update nfs-utils可以解决
6、update nfs-utils
yum update nfs-utils 问题解决
[root@node2 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/cl-root 46G 2.1G 44G 5% /
devtmpfs 910M 0 910M 0% /dev
tmpfs 920M 12K 920M 1% /dev/shm
tmpfs 920M 8.5M 912M 1% /run
tmpfs 920M 0 920M 0% /sys/fs/cgroup
/dev/sda1 1014M 146M 869M 15% /boot
system1.domain1.example.com:/product 46G 2.1G 44G 5% /mnt/product
tmpfs 184M 0 184M 0% /run/user/0

7、nfs-utils版本更新前后
[root@node1 log]# rpm -qa | grep nfs
nfs-utils-1.3.0-0.33.el7.x86_64

[root@node1 log]# rpm -qa | grep nfs
nfs-utils-1.3.0-0.54.el7.x86_64