Linux NFS Network File System and nfs Network File System

Linux NFS Network File System and nfs Network File System

I. Introduction to the NFS service

NFS is short for Network File System, that is, Network File System. An agreement for the use of distributed file systems, developed by sun, was published on April 9, 1984. Function: allows different machines and operating systems to share individual data over the network, allowing applications to access data on the server disk over the network, it is a way to share disk files between Unix-like systems.

The basic principle of NFS is to "allow different clients and servers to share the same file system through a group of RPC", which is independent of the operating system, allows different hardware and operating system systems to share files.

NFS depends on the RPC protocol during file transfer or information transfer. RPC: Remote Procedure Call is a mechanism that enables the client to execute other system programs. NFS itself does not provide information transmission protocols and functions, but NFS allows us to share data over the network, because NFS uses some other transmission protocols. These transmission protocols use this RPC function. NFS itself is a program that uses RPC. Or NFS is an rpc server. Therefore, the RPC service must be started wherever NFS is located. Summary: NFS is only a file system, while rpc is responsible for information transmission.

Ii. Install the NFS service

Two software packages are required for NFS.

Nfs-utils-* includes basic NFS commands and monitoring programs

Rpcbind-* supports Secure nfs rpc service connections

1. Check whether NFS is installed in the system.

Rpm-qa | grep nfs

Rpm-qa | grep rpcbind

If not, yum grouplist and yum groupinstall "NFS"

Iii. NFS server configuration

Common NFS directories

Main configuration file of/etc/exports NFS service

/Usr/sbin/exportfs NFS service management command

/Usr/sbin/showmount client view command

/Var/lib/nfs/etab records the complete permission settings for the directories shared by NFS.

/Var/lib/nfs/xtab records client information that has been logged on

The NFS service configuration file is/etc/exports, and the system does not have the default value. Therefore, this file may not exist. You can use vim to manually create it and then write the configuration content in the file.

/Etc/exports file content format:

<Output directory> [client 1 option (access permission, user ing, and others)] [client 2 Option (access permission, user ing, and others )]

A. output directory: the output directory is the directory that needs to be shared to the client in the NFS system.

B. Client: computer that can access the NFS output directory in the Network

Common Methods for specifying a client:

Host with the specified IP Address: 192.168.0.200

All hosts in the specified subnet: 192.168.0.0/24 192.168.0.0/255.255.255.0

Host for the specified domain name: David .bsmart.cn

All hosts in the specified domain name: * .bsmart.cn

All Hosts :*

C. Option: used to set the access permission and user ing of the output directory.

NFS has three main options:

Access permission options

Set output directory read-only: ro

Set output directory read/write: rw

User ing options

All_squash: maps all common users and groups remotely accessed to anonymous users or user groups (nfsnobody)

No_all_squash: opposite to all_squash (default)

Root_squash: maps root users and their groups to anonymous users or user groups.

No_root_squash: opposite to top

Anonuid = xxx: maps all remotely accessed users to anonymous users and specifies the user as a local user.

Anongid = xxx: maps all remotely accessed user groups to anonymous user group accounts, and specifies that the anonymous user group account is a local user group account.

Other options (ignore, use the default value)

Iv. Start and Stop an NFS server

After correctly configuring the/etc/exports file, you can start the NFS server.

1. Start the NFS server

To enable the nfs server to work properly, you need to start the rpcbind and nfs services, and the rpcbind must be started before nfs.

Service rpcbind start

Service nfs start

2. query the nfs server status

Service rpcbind status

Service nfs status

3. Stop the nfs server

To stop nfs, stop nfs and then stop the rpcbind service. If there are other services in the system (such as nis) that need to be used, you do not need to stop the rpcbind service.

Service nfs stop

Service rpcbind stop

4. Set the Automatic startup status of the nfs server

Chkconfig -- add

Chkconfig -- level 35

V. Instances

1. Share the/home/cairui of the NFS server to 192.168.66.128 for read and write permissions.

# Vim/etc/exports

/Home/cairui 192.168.66.128/24 (rw)

2. Restart the rpcbind and nfs services.

Service rpcbind restart

Service nfs restart

Exportfs

3. The server uses the showmount command to query the NFS sharing status.

Showmount-e

Showmount-a: displays the directory information that has been connected to the client.

4. The client uses the showmount command to query the nfs sharing status.

Showmount-e Server ip Address

5. Mount the shared directory in the nfs server on the client.

Command Format: mount NFS server IP Address: shared directory local mount point directory

Check whether the mounting is successful: mount | grep nfs

Check whether the file is consistent with the server

6. NFS share permission and Access Control

Modify permissions on the server/home/cairui to make the client writable and readable.

Chmod 777-R/home/cairui

6. unmount the mounted NFS shared directory

Format: umount/tmp/cai

8. Start automatic mounting of the nfs File System

Format: <server >:< remote/export>

</Local/directory> nfs <option> 0 0

# Vim/etc/fstab

The last line is the appended

Save and exit. restart the system.