[NFS服务器] mount.nfs: access denied by server while mounting问题解决

mount.nfs: access denied by server while mounting 一个解决办法

          这两天在搭建嵌入式开发环境，配置好NFS服务器后，遇到了一个很纠结的错误
使用 mount -t nfs 127.0.0.1:/home/lzgonline/rootfs /mnt 和 mount -t nfs 192.168.1.9:/home/lzgonline/rootfs /mnt 本机挂载nfs则没有问题，然而使用 mount -t nfs 192.168.3.12:/home/lzgonline/rootfs /mnt 时却出现了问题，导致开发板无法通过nfs挂载启动，其中192.128.3.12 和 192.128.1.9（即nfs服务器）之间建立了映射（DMZ）关系。
mount.nfs: access denied by server while mounting 192.168.3.12:/home/lzgonline/rootfs
百度、谷歌了很久，大部分都说是权限设置有问题，其实文件夹权限都设为777了，权限上都没问题，hosts.deny和hosts.allow都保留默认设置，防火墙也关了，该设置的都设置了，但还是被拒绝，很是郁闷，就在一筹莫展的时候，通过查看一些linux技术论坛后逐渐找到了问题所在。
首先使用命令查看出错日志文件
[root@lzgonline init.d]# cat /var/log/messages | grep mount
Jun 29 00:49:04 lzgonline mountd[1644]: refused mount request from 192.168.3.12 for /home/lzgonline/rootfs (/home/lzgonline/rootfs): illegal port 1689
Jun 29 00:51:02 lzgonline mountd[1644]: refused mount request from 192.168.3.12 for /home/lzgonline/rootfs (/home/lzgonline/rootfs): illegal port 1710
Jun 29 01:02:17 lzgonline mountd[1644]: refused mount request from 192.168.3.12 for /home/lzgonline/rootfs (/home/lzgonline/rootfs): illegal port 1916
Jun 29 01:09:51 lzgonline mountd[1644]: refused mount request from 192.168.3.12 for /home/lzgonline/rootfs (/home/lzgonline/rootfs): illegal port 2157
Jun 29 01:17:02 lzgonline mountd[1644]: refused mount request from 192.168.3.12 for /home/lzgonline/rootfs (/home/lzgonline/rootfs): illegal port 2318
 
从出错日志可以看出，mount.nfs: access denied by server while mounting 192.168.3.12:/home/lzgonline/rootfs 被拒绝的原因是因为使用了非法端口，功夫总没白费，终于在一个linux技术论坛上找到了答案：
I googled and found that since the port is over 1024 I needed to add the "insecure" option to the relevant line in /etc/exports on the server. Once I did that (and ran exportfs -r), the mount -a on the client worked.
//如果端口号大于1024，则需要将 insecure选项加入到配置文件（/etc/exports）相关选项中mount客户端才能正常工作:
查看 exports 手册中关于 secure 选项说明也发现确实如此
[root@lzgonline init.d]# man exports
secure,This  option requires that requests originate on an Internet port less than IPPORT_RESERVED (1024). This option is on by default. To turn it off, specify insecure.
//secure 选项要求mount客户端请求源端口小于1024（然而在使用 NAT 网络地址转换时端口一般总是大于1024的），默认情况下是开启这个选项的，如果要禁止这个选项，则使用 insecure 标识
修改配置文件/etc/exports，加入 insecure选项
/home/lzgonline/rootfs  *(insecure,rw,async,no_root_squash)
保存退出
然后重启nfs服务：service nfs restart
然后问题就解决了