Linux**-Server - Network-File-System (NFS) -Server

A prerequisite to allow users on other computers within the network access to the directories accessible to all users (see Linux-server - file-structure and users) is, that a NFS-Server is installed and activated on the Linux**-Server.

Automated start of the NFS-service:

To configure automatic startup the command
ntsysv
is executed on the command-line.

On the following 'Services'-menu the selection [ ] nfs is marked with the space-bar and the and confirmed with the OK-button.

Definition of the directories, where the access-rigts should be controlled by NFS:

Directories, which should be accessible for other computers, are defined in the cinfiguration file /etc/exports by entering the following lines:

/SMB_Disk/data_backed_up 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/data_not_backed_up 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/finance 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/progs_honest 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/progs_writing 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/backup_mirror 192.168.0.0/255.255.255.0(ro)
/SMB_Disk/cd_01 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_02 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_03 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_04 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_05 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_06 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_07 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_08 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_09 192.168.0.0/255.255.255.0(rw)
/SMB_Disk/cd_10 192.168.0.0/255.255.255.0(rw)

To copy the above configuration-statements to a file follow this link for an explanation how to copy text from a web-browser to a file.

Definition of the computers (TCP/IP-adresses), which are allowed to access the directories

This is done by defining which of the TCP/IP-adresses (belonging to computers) are allowed to use the services of the NFS.

To increase the security, all TCP/IP-adresses are preventive excluded in the configuration-file /etc/hosts.deny :

#
# hosts.deny This file describes the names of the hosts which are
# *not* allowed to use the local INET services, as decided
# by the '/usr/sbin/tcpd' server.
#
# The portmap line is redundant, but it is left to remind you that
# the new secure portmap uses hosts.deny and hosts.allow. In particular
# you should know that NFS uses portmap!
portmap: ALL
lockd: ALL
mountd: ALL
rquotad: ALL
statd: ALL

To copy the above configuration-statements to a file follow this link for an explanation how to copy text from a web-browser to a file.

Then only the TCP/IP-adresses of the own (internal) network are included in the configuration-file /etc/hosts.allow  :

#
# hosts.allow This file describes the names of the hosts which are
# allowed to use the local INET services, as decided
# by the '/usr/sbin/tcpd' server.
portmap: 192.168.0.0/255.255.255.0
lockd: 192.168.0.0/255.255.255.0
rquotad: 192.168.0.0/255.255.255.0
mountd: 192.168.0.0/255.255.255.0
statd: 192.168.0.0/255.255.255.0

To copy the above configuration-statements to a file follow this link for an explanation how to copy text from a web-browser to a file.

To avoid a shutdown and restart of the Linux**-Server, the new configuration can be activated immediately by restarting service nfs with the following command:
service nfs restart

Test for correct installation of the NFS on the Linux**-Server:

After restarting the service, a list of active services can be displayd by entering the command  
rpcinfo -p  
on the command-line of the terminal. The result looks similar to the following output.

In this list the services rquotad, mountd, nfs and nlockmgr must appear.

Check for correct installation of the NFS on the Linux**-Server on any Linux**-Workstation on the network.

Show the allowed NFS-directories on a remote computer:

If a the user 'root' executes the command
showmount -e 192.168.0.1  
then all allowed directories on the Server (with TCP/IP-adress 192.168.0.1) will be listed.

If the standard-directory-structure (as described in the document Linux - file-structure and users) is installed on the Server, then the list looks like this:

Mount a NFS-directory as local directory:

Logging in as 'root' and issuing the following command
mount 192.168.0.1:/SMB_Disk/data_backed_up /mnt/floppy  
mounts the specified directory on the Server (with TCP/IP-adress 192.168.0.1) to the directory 'mnt/floppy' on the local computer.
N.B. '/mnt/floppy' is used for convinience now as this directory already exists; for permanent mounting an extra directory will be created. This is described in document Auxiliary Linux**-service-applications.

Logging off 'root' and logging on as a user with the proper access-rights on the mounted directory gives the change to read or modify files on the mounted directory.

Additional Hints:

Executing ntsysv, editing configuration-files and listing the services can only be done when logged on as user 'root'.

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