NFS server side :

yum -y install nfs-utils 
yum install nfs-kernel-server

sudo mkdir /mnt/myshareddir

sudo chown nobody:nogroup /mnt/myshareddir #no-one is owner 
sudo chmod 777 /mnt/myshareddir #everyone can modify files

vi    /etc/exports

/mnt/myshareddir {clientIP-1}
(rw,sync,no_subtree_check)
{clientIP-2}(...)
{clientIP-3}(...)

/mnt/myshareddir 
{subnetIP}/{subnetMask}
(rw,sync,no_subtree_check)


sudo exportfs -a #making the file share available 
sudo systemctl restart nfs-kernel-server #restarting the NFS kernel

 sudo ufw allow

NFS client side : 
sudo yum install nfs-utils
sudo mkdir /var/locally-mounted
sudo mount -t nfs {IP of NFS server}:{folder path on server} /var/locally-mounted
sudo mount -t nfs 192.168.20.100:/myshareddir /var/locally-mounted

vi   /etc/fstab
{IP of NFS server}:{folder path on server} /var/locally-mounted nfs defaults 0 0
mount /var/locally-mounted 
mount {IP of NFS server}:{folder path on server}
