Description of problem:

Server = RHEL 6 CSB
Client = RHEL 5.7 workstation

with 5.7 set up as the server I could mount dirs on CSB ok.
With CSB as the server I had to jump through all sorts of hoops (ask steved) to get it working.

Mostly I received the following sorts of errors:
failed: RPC Error: Authentication error
mount: mount to NFS server 'daobrien' failed: RPC Error: Program not registered

Trying with nfs4 produced:
mount.nfs4: Permission denied

Firewall on both ends disabled.
SELinux in permissive.

Command used on client:
[root@jupiter ~]# mount -vvv daobrien:/home/daobrien/sandbox/OpenShift /home/david/sandbox/

# cat /etc/exports
/home/daobrien/sandbox/OpenShift *(rw,no_root_squash)

Version-Release number of selected component (if applicable):
Server:
nfs-utils-1.2.3-7.el6.x86_64
nfs-utils-lib-1.1.5-3.el6.x86_64

Client:
nfs-utils-lib-1.0.8-7.6.el5
nfs-utils-1.0.9-54.el5

How reproducible:


Steps to Reproduce:
1. Export a dir on the server
2. Disable both firewalls while setting up/testing
3. Run mount command as described above
  
Actual results:
Error messages as shown above. /var/log/messages also shows messages like:
Aug  9 02:25:30 daobrien rpcbind: connect from 192.168.1.5 to getport/addr(nfs): request from unauthorized host


Expected results:


Additional info:
eventually ran this to get it to work:
pkill rpc.mountd && service nfslock restart && service nfs restart

AND

commented out all lines in /etc/hosts.allow
# ALL:            127.0.0.1       : ALLOW
# sshd:           ALL             : ALLOW
# ALL:            ALL             : DENY

http://fpaste.org/Kwtg/ has rpcinfo -p (for now).

I did try adding nfsd to the allow list but that didn't help.