NFS share is not getting mounted when services denied in /etc/hosts.deny file Environment

        NFS share is not getting mounted when services denied in /etc/hosts.deny file

Environment

• Red Hat Enterprise Linux (RHEL) 7
• NFS version 3

Issue

• Unable to mount NFS share as version=3 getting 'permission denied error message' but nfs4 works fine
• showmount -e is showing 'clnt_create: RPC: Port mapper failure - Authentication error'
• rpcinfo -p <nfs-server> is showing 'rpcinfo: can't contact portmapper: RPC: Authentication error; why = Client credential too weak'

Resolution

• Check if any daemon is denied in /etc/hosts.deny file

# cat /etc/hosts.deny

ALL: ALL

• If tcp_wrapper is used in your environment make an entry of mountd and rpcbind in /etc/hosts.allow file

# cat /etc/hosts.allow

sshd: ALL

rpcbind: ALL

mountd: ALL

Root Cause

• As every daemon was blocked/denied hence there was an authentication error and unable to mount nfs share

Diagnostic Steps

• Getting permission denied while trying to mount share as version=3

 [root@dhcp4-54 ~]# mount -t nfs -o vers=3  dhcp4:/nfs /mnt/

mount.nfs: access denied by server while mounting dhcp4:/nfs

• showmount -e throws below authentication error

 [root@dhcp4-54 ~]# showmount -e dhcp4

clnt_create: RPC: Port mapper failure - Authentication error

• rpcinfo shows 'Client credential too weak'

 [root@dhcp4-54 ~]# rpcinfo -p  dhcp4

rpcinfo: can't contact portmapper: RPC: Authentication error; why = Client credential too weak