Linux Learning NFS Instances

After you have configured the exports file correctly, you can start the NFS server.

1. Start the NFS server

In order for the NFS server to work properly, you need to start Portmap and NFS two services, and Portmap must start before NFS.

# Service Portmap start# Service NFS Start

2. Querying Server Status for NFS

# Service Portmap status# Service NFS Status  

3. Stop Server for NFS

To stop the NFS runtime, you need to stop the NFS service before stopping the Portmap service, and you do not need to stop the Portmap service if there are other services in the system (such as NIS) that you need to use

# Service NFS stop# service Portmap stop

4. Set the auto-start Status for NFS server

For the actual application system, it is unrealistic to manually start the NFS server after each boot of the Linux system, and it is necessary to set the system to automatically start the Portmap and NFS services at the specified runlevel.

# chkconfig--list portmap# Chkconfig--list NFS

Set Portmap and NFS services to start automatically at System run level 3 and 5.

# chkconfig--level portmap on# chkconfig--level NFS on

Vii. examples

1, the NFS Server/home/david/share to the 192.168.1.0/24 network segment, permissions read and write.

Server-side files are detailed as follows:

# Vi/etc/exports

/home/david 192.168.1.0/24 (rw)

2. Restart Portmap and NFS Services

# Service Portmap restart# service NFS restart# Exportfs

3, server side use the showmount command to query the sharing status of NFS

# SHOWMOUNT-E//default view of their shared services, provided that the DNS can resolve their own, otherwise prone to error

# SHOWMOUNT-A//Displays directory information that has been connected to the client

4. The client uses the Showmount command to query the shared status of NFS

# SHOWMOUNT-E NFS Server IP

5. The client mounts the shared directory in the NFS server

Command format

# Mount NFS Server IP: Shared directory local mount point directory

# Mount 192.168.1.108:/home/david//tmp/david/

# Mount |grep NFS

Mounted successfully.

See if the file is consistent with the server side.

6. Sharing permissions and access Control for NFS

Now let's create a file in/tmp/david/and see what the permissions are.

# Touch 20130103

The permission denied appears here because the Write permission on the NFS server-side shared directory itself is not open to other users, and the permission is opened on the server side.

# chmod 777-r/home/david/

Create a file in client/tmp/david/again

I used the root user to create a file that became a nfsnobody user.

NFS has a number of default parameters, open/var/lib/nfs/etab to view the shared/home/david/full permission set value.

# Cat/var/lib/nfs/etab

The default is sync,wdelay,hide and so on, No_root_squash is to allow root to maintain permissions, Root_squash is to map root to Nobody,no_all_squash do not keep all users in the Mount directory permissions. Therefore, the file owner created by Root is nfsnobody.

Below we use normal user mount, write file test.

# Su-david

$ Cd/tmp/david/

$ Touch 2013david

ordinary users write to the file is their own name, which will ensure the security of the server.

On the analysis of permissions

1. When the client connects, the check for the ordinary user

A. If the identity of the normal user is explicitly set, then the identity of the client user is converted to the specified user;

B. If there is a user with the same name on NFS server, then the identity of the client login account is converted to the same user name as NFS server;

C. If there is no explicit designation, there is no user of the same name, then the user identity is compressed into nfsnobody;

2. When the client connects, the root check

A. If the No_root_squash is set, then the root user's identity is compressed to root on NFS server;

B. If All_squash, Anonuid, Anongid are set, the root identity is compressed to the specified user;

C. If there is no explicit designation, the root user is compressed to nfsnobody at this time;

D. If you specify both No_root_squash and All_squash users will be compressed to Nfsnobody, if set Anonuid, Anongid will be compressed to the specified user and group;

7. Unmount The mounted NFS shared directory

# Umount/tmp/david/

Eight, start Automatic Mount NFS file system

Format:

<server>:</remote/export> </local/directory> NFS < options> 0 0

# Vi/etc/fstab

Save the exit and restart the system.

Check to see if the/home/david is automatically mounted.

Automatic mount succeeded.

Ix. Related Orders

1, Exportfs

If we change/etc/exports after we start NFS, do we have to restart NFS? At this point we can use the EXPORTFS command to make the change take effect immediately, the command format is as follows:

# Exportfs [-aruv]

-A all mount or unload content in/etc/exports
-R re-reads the information in/etc/exports and synchronizes updates/etc/exports,/var/lib/nfs/xtab
-U Uninstalls a single directory (used together with-A to unload directories in all/etc/exports files)
-V Exports detailed information to the screen at the time of export.

Specific examples:
# Exportfs-au Uninstall all shared directories
# EXPORTFS-RV re-share all directories and output detailed information

2, Nfsstat

Viewing the running Status of NFS is a great help in adjusting the operation of NFS.

3, Rpcinfo

View RPC execution information, a tool that can be used to detect RPC health, and use RPCINFO-P to see what programs are available for RPC-enabled ports.

4, Showmount

-A displays directory information that is already on the client connection
-e IP or hostname display the directory shared by this IP address

5, Netstat

You can view the ports that are open for NFS service, where NFS is turned on by 2049,portmap 111 and the rest is RPC enabled.

Finally note two points, although the permission settings can be accessed by ordinary users, but when mounted by default only root can be mounted, ordinary users can execute sudo.

When NFS server shuts down, make sure that the NFS service is down and no clients are connected! Showmount-a can be viewed, if any, with kill Killall Pkill to end, (-9 forced end)

Linux Learning NFS Instances