Network File system
Service Profile: nfs and portmap
Configuration File: /etc/exports
Port Number: 2049 portmap: 111
Log File: /var/log/messages
Versions available: Version 2, 3 & 4 NFS V3 VS NFS V4
Export Management- In NFSv3, client must rely on auxiliary protocol, the mount protocol to request a list of server’s exports and obtain root filehandle of a given export. It is fed into the NFS protocol proper once the root filehandle is obtained.
- In NFSv4 uses the virtual file system to present the server’s export and associated root filehandles to the client.
- NFSv4 defines a special operation to retrieve the Root filehandle and the NFS Server presents the appearance to the client that each export is just a directory in the pseudofs
- NFSv4 Pseudo File System is supposed to provide maximum flexibility. Exports Path name on servers can be changed transparently to clients.
- NFSv3 is stateless. In other words if the server reboots, the clients can pick up where it left off. No state has been lost.
- NFSv3 is typically used with NLM, an auxiliary protocol for file locking. NLM is stateful that the server LOCKD keeps track of locks.
- In NFSv4, locking operations are part of the protocol
- NFSv4 servers keep track of open files and delegations
- NFSv3 rely on NLM. Basically, Client process is put to “sleep”. When a callback is received from the server, client process is granted the lock.
- For NFSv4, the client to put to sleep, but will poll the server periodically for the lock.
- The benefits of the mechanism is that there is one-way reachability from client to server. But it may be less efficient.
To configure NFS share we have to install below packages
~]#rpm -qa |grep nfs
Nfs-utils are installed in my system, if there is no nfs-utils in your server please install
~]# yum install nfs*
# yum install xinet*
Start NFS, Portmap and Xinetd services
~]# service portmap restart
~]# service xinetd restart NFS uses tcp_wrappers for additional security. The service for tcp_wrappers is portmap. Add an entry to /etc/hosts.allow to allow the 192.168.0.0/24 subnet access to NFS service.
~]# service nfs restart
Verify the port nfs is working
~]# rpcinfo -p |grep nfs
Share the directory or disk using NFS
To sharing the Directory/Disk we have edit the /etc/exports and add the entries
CLIENT SIDE
Go to Client machine and check it out share is accessible
~]# showmount -e 192.168.234.132
Now mount the share to your local mount point
~]# mount -t nfs 192.168.234.132:/qcheck /mnt
Likewise you can provide the permissions to NFS share
Here are the most common NFS export techniques and options:
/home/nfs/ 192.168.234.123(rw,sync)
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export /home/nfs directory for host with an IP address 192.168.234.123 with read, write permissions, and synchronized mode
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/home/nfs/ 192.168.234.0(ro,sync)
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export /home/nfs directory for network 192.168.234.0 with netmask 255.255.255.0 with read only permissions and synchronized mode
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/home/nfs/ 192.168.234.123(rw,sync) 192.168.234.124 (ro,sync)
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export /home/nfs directory for host with IP 192.168.234.123with read, write permissions, synchronized mode, and also export /home/nfs directory for another host with an IP address 192.168.234.124 with read only permissions and synchronized mode
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/home/nfs/ 192.168.234.123 (rw,sync,no_root_squash)
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export /home/nfs directory for host with an IP address 192.168.234.123with read, write permissions, synchronized mode and the remote root user will be treated as a root and will be able to change any file and directory.
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/home/nfs/ *(ro,sync)
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export /home/nfs directory for any host with read only permissions and synchronized mode
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/home/nfs/ *.linuxcareer.com(ro,sync)
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export /home/nfs directory for any host within linuxconfig.org domain with a read only permission and synchronized mode
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/home/nfs/ foobar(rw,sync)
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export /home/nfs directory for hostname foobar with read, write permissions and synchronized mode
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Mounting NFS share as permanent, we have to edit /etc/fstab, if you want restart and verify the mount point
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