I discovered this problem while attempting to share our automounted home directories from my Solaris 10 NFS file server to my SUSE and Red Hat Linux NFS clients.
automount[10581]: >> mount: block device 192.168.0.2:/data/home/samiller is write-protected, mounting read-only
kernel: call_verify: server 192.168.0.2 requires stronger authentication.
It turns out that the solution is quite simple. The issue is with a mismatch of anonymous credentials. Let’s take a look at the erroneous entry in /etc/dfs/dfstab on the Solaris NFS server:
share -F nfs -o public,nosuid,rw,anon=-1 -d "backup" /data
The piece of this configuration that is an issue here is “anon=-1”. In theory this is designed to block users who do not have accounts on the local system. However this causes issues with Linux systems. You can solve this problem by simply removing the anon setting from the configuration file. Not an ideal fix but it does solve the problem.
share -F nfs -o public,nosuid,rw -d "backup" /data
Simply run the “shareall” command and you should be back in business.