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This article will explain in detail how to achieve nfs sharing between the two hosts of linux. The content of the article is of high quality, so the editor will share it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

A service for sharing files in NFS:Network File System,linux.

To use NFS, you need to enable RPC (remoteprocedure call), and RPC can specify the port number corresponding to each NFS function. After restarting RPC, all NFS services managed by RPC need to be re-registered with RPC.

To set up NFS sharing, you need to install nfs and portmap packages. Use rpm-qa to check whether to install or not.

Nfs-utils-lib-1.0.8-7.6.el5, nfs-utils-1.0.9-50.el5 and portmap-4.0-65.2.2.1 programs

Nfs-utils: provide two daemon of rpc.nfsd and rpc.mountd and other document documentation.

Rpc.nfsd: manages whether the client can log in to the host and identify the login ID.

Rpc.mountd: manage the NFS file system, and read / etc/exports to get the corresponding permissions compared with client.

Portmap: Port mapping; do port mapping before starting rpc.

There are two configuration files for NFS:

/ etc/exports:NFS configuration file

/ var/lib/nfs/*tab:NFS server log placement path; etab records the full permission settings of the shared directory; xtab records relevant client data that has been connected to this NFS host

Two commands:

/ usr/sbin/exportfs: maintain NFS shared resources; re-share / etc/exports change directories or uninstall or re-share NFSserver shared directories

/ usr/sbin/showmount: view the directory resources shared by the NFS server on the client

/ etc/exports configuration file

First, you need to manually edit the / etc/exports configuration file

Note the following two points:

Shared directory: absolute path must be used. Permissions are shared to different hosts according to different permissions. Parentheses are the location where permission parameters are set. When there is more than one permission, use, separation, hostname and parentheses are linked together.

Hostname setting: you can use the network segment: 192.168.1.0 IP:192.168.1.23 24 or the full IP:192.168.1.23 can also use the hostname, but this hostname needs to exist in / etc/hosts or can be found using DNS, just find IP, hostname supports wildcards, such as * or?

/ mnt/sda4/share/a 192.168.23.129 (sync,rw)

Sync: synchronously writes data to memory and hard disk async: data is temporarily stored in memory rather than written directly to the hard disk

Set the shared directory / mnt/sda4/share/a. Only 192.168.23.129 hosts are allowed to access this shared directory and have read and write permissions

/ mnt/sda4/share/b 192.168.23.129 (rw) * (ro)

Set the shared directory / mnt/sda4/share/b,192.168.23.129 to read and write to the shared directory, (*) other hosts can only read the shared directory

/ mnt/sda4/share/c 192.168.23.129 (no_root_squash)

Set the shared directory / mnt/sda4/share/c. Only 192.168.23.129 can access, read and write. Root has root permission when logging in.

/ mnt/sda4/share/d 192.168.23.0 Compact 24 (rw)

Set the shared directory / mnt/sda4/share/d, which can only be accessed, read and written by hosts on the 24 network segment of 192.168.23.0.

/ mnt/sda4/share/e * (rw,all_squash,anonuid=500,anongid=500)

Set up the shared directory / mnt/sda4/share/e, which all hosts are allowed to access and have read and write access to, but they have set their UID and GID to 500when they access the shared directory. The permissions of UID and GID=500 in the NFSserver host have been set.

The permission parameters are described as follows:

Read and write permissions for Rw:read-write

Ro:read-only read-only permission

No_root_squash: a user who logs in to a NFS host to use a shared directory. If the user root, has root permission for this shared directory, it is not recommended.

Root_squash: users who log in to the NFS host to use a shared directory. If the user root, this user right will be compressed to anonymous users, and their UID and GID will be compressed to the identity of the nobody (nfsnobody) system account.

All_squash: regardless of the identity of the user who logs in to NFS, his identity is converted to an anonymous user, that is, nobody.

Anonuid:anonymous; is nobody, and you can set this UID value yourself, but this UID must exist in / etc/passwd.

Anongid: the same as anonuid, it can be changed to group ID.

Sync: write data synchronously to memory and hard disk

Async: data is temporarily stored in memory rather than written directly to the hard disk

Permission description:

1.NFS server and NFS client have the same UID and account

If NFSserver and NFSclient have the same shared file account and the same UID, the client will have the permission set by / etc/exports when logging in to NFSserver

2.NFS server and NFS client have different accounts

If NFSclient does not have an NFSserver shared file account, or the NFSclient account does not exist in NFSserver, whether you can read and write to the shared directory depends on the permission to view NFSserver, and its identity will become anonymous user nobody.

The identity of 3.NFS client is root

By default, the root identity of the client is compressed to an anonymous user nobody

Start NFS

To start NFS, you only need to start the portmap and NFS services.

# service nfs start # service portmap start

If you need to start a data consistency check, start the nfslock service.

Using netstat-tnlu, you can see which ports are open by nfs. The port of Portmap is 111, and the port of nfs is 2049.

[root@localhost share] # rpcinfo-p

Program version Protocol Port Service name

100000 2 tcp 111 portmapper

100000 2 udp 111 portmapper

100024 1 udp 695 status

100003 2 udp 2049 nfs

100021 1 udp 46017 nlockmgr

...

If the rpcinfo-p data cannot be exported, it indicates that there is a problem with the registered data, just restart portmap and nfs.

Client to see what NFS services Server provides, you can use showmount

# showmount-e displays directory data shared by / etc/exports of a host

# showmount-a displays the status of online sharing between the host and the client NFS

# showmount-e

Export list for localhost.localdomain:

/ mnt/sda4/share/e *

/ mnt/sda4/share/d 192.168.23.0/24

/ mnt/sda4/share/c 192.168.23.129

/ mnt/sda4/share/b (everyone)

/ mnt/sda4/share/a 192.168.23.129

You need to scan the NFS shared directory provided by a host and use showmount-e ip (hostname).

Check / var/lib/nfs/etab to view NFSserver directory permission settings

# cat / var/lib/nfs/etab

/ mnt/sda4/share/a 192.168.23.129 (rw,sync,wdelay,hide,nocrossmnt,secure,root_squash,no_all_squash,no_subtree_check,secure_locks,acl,mapping=identity,anonuid=65534,anongid=65534)

.

If you do not need to restart nfs after modifying the / etc/exports file, just scan the file / etc/exports once and load the settings again

Exportfs:

-a: Mount (or uninstall) all the settings in the / etc/exports file.

-r: remount the settings in / etc/exports and update the contents of / etc/exports and / var/lib/nfs/xtab synchronously.

-u: uninstall a directory.

-v: in export, the shared directory is displayed on the screen.

Settings for remounting / etc/exports: # exportfs-arv

Uninstall all / etc/exports settings: # exportfs-auv

Client configuration:

# mkdir-p / mnt/share/client/b

# mount-t nfs 192.168.23.128:/mnt/sda4/share/b / mnt/share/b

Note: if you need to modify the mount directory, you can operate mount-- move / mnt/share/b / usr/local/test

# df-h

File system 1K-Block used available used% mount point

/ dev/sda2 5952284 3158868 2486176 56%

/ dev/sda1 101086 11481 84386 12% / boot

Tmpfs 127720 0 127720 / dev/shm

192.168.23.128:/mnt/sda4/share/b 3905632 73408 3633824 2% / usr/local/test

If it needs to be set to boot and mount

Please modify the / etc/fstab file

192.168.23.128:/mnt/sda4/share/e / usr/local/test nfs defaults,rw 0 0

In addition, you can use autofs to set the client to mount automatically when needed, and unmount automatically after a few minutes when you don't need it. You can also set some parameters when / etc/fstab or the client mounts manually to facilitate the client to use.

On how to achieve linux two hosts nfs sharing to share here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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