Is there any way to configure Solaris NFS server to not backresolve IPs of the client machines when checking access control, except specifying @ before every IP? We never use hostnames so would like to force it to work with IPs only.
Add the hostnames that will connect to your server to the /etc/hosts file.
Make sure the /etc/nsswitch.conf file lists 'file' in the dns line (it's the default).
There is no way to tell the code NOT to look up hostnames so you must "cheat" by forcing it in /etc/hosts.