About NFS
The acronym NFS (Network File System), its main function is: through the network, so that different machines, different OS can share each other's files
NFS server can allow NFS client NFS server's shared directory distal to mount its own NFS client, so the client is like there is a piece in the local disk, like, just a network disk only.
Mount structure of FIG.
As shown above, when we set up a shared directory / data / share on the NFS server, the other has access to NFS client NFS server can tell this to their own local directory is mounted, and can see the server / data All data in / share
NFS is carried out by a network of data transmission between Server and Client-side end, since walking network, the two sides certainly should have port, which NFS Server how to know which port to use for data transmission, in fact, NFS will randomly select a port for data transmission. That NFS client and NFS server know how in the end is which port to use it? In fact, the NFS server is done by remote procedure calls RPC (Remote Procedure Call) protocol, therefore, NFS port assignment RPC management server, the client to transfer data, the client's RPC will begin with server-side RPC to go to the server's port , to the port, the re-connection is established, and data transmission, see below
NFS client / NFS server, RPC diagram
Communication process:
1. First start the RPC server-side service, and open port 111
2. Start the NFS server service, and RPC ports registration information
3. RPC client starts the service, the service request to the server end of the NFS RPC service port
4. The service side of the NFS RPC service port feedback information to the client.
The NFS client and server to establish a connection and transmitting data acquired by the NFS port.
Machinery list
| CPU name |
IP addresses |
Operating system version |
Remark |
| node100 |
172.20.20.100 |
NFS server |
|
| node200 |
172.20.20.200 |
NFS Client |
lab environment
CentOS：CentOS Linux release 7.6.1810 (Core)
2 stations are operating
Configuring the host name:
# cat >> /etc/hosts << EOF
172.20.20.100 node100
172.20.20.200 node200
EOF
NFS server operation
# rpm -qa nfs-utils rpcbind
# yum install nfs-utils rpcbind
Create a directory
# mkdir -p /data/share
# chmod 666 /data/share/
# cat >> /etc/exports << EOF
/data/share 172.20.20.0/24(rw,sync,insecure,no_subtree_check,no_root_squash)
EOF
# mkdir -p /data/share/soft/
Start the RPC service
# systemctl start rpcbind.service
[root@node100 ~]# ps -ef|grep rpcbind
rpc 15712 1 0 03:41 ? 00:00:00 /sbin/rpcbind -w
root 15714 8035 0 03:41 pts/0 00:00:00 grep --color=auto rpcbind
[root@node100 ~]# rpcinfo -p localhost
program vers proto port service
100000 4 tcp 111 portmapper
100000 3 tcp 111 portmapper
100000 2 tcp 111 portmapper
100000 4 udp 111 portmapper
100000 3 udp 111 portmapper
100000 2 udp 111 portmapper
Start the NFS Services
# service nfs start
[root@node100 ~]# rpcinfo -p localhost
program vers proto port service
100000 4 tcp 111 portmapper
100000 3 tcp 111 portmapper
100000 2 tcp 111 portmapper
100000 4 udp 111 portmapper
100000 3 udp 111 portmapper
100000 2 udp 111 portmapper
100024 1 udp 40044 status
100024 1 tcp 34946 status
100005 1 udp 20048 mountd
100005 1 tcp 20048 mountd
100005 2 udp 20048 mountd
100005 2 tcp 20048 mountd
100005 3 udp 20048 mountd
100005 3 tcp 20048 mountd
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100227 3 tcp 2049 nfs_acl
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100227 3 udp 2049 nfs_acl
100021 1 udp 37957 nlockmgr
100021 3 udp 37957 nlockmgr
100021 4 udp 37957 nlockmgr
100021 1 tcp 43494 nlockmgr
100021 3 tcp 43494 nlockmgr
100021 4 tcp 43494 nlockmgr
Whether to load the configuration / etc / exports
[root@node100 ~]# showmount -e localhost
Export list for localhost:
/data/share 172.20.20.0/24
In the NFS client installation
# yum install nfs-utils
[Root @ node200 ~] # showmount -e 172.20.20.100
Export list for 172.20.20.100:
/data/share 172.20.20.0/24
Test the NFS client
# mkdir /root/soft/
# mount 172.20.20.100:/data/share/soft /root/soft
[root@node200 soft]# df -Th
Filesystem Type Size Used Avail Use% Mounted on
/dev/sda3 xfs 36G 1.1G 35G 4% /
devtmpfs devtmpfs 224M 0 224M 0% /dev
tmpfs tmpfs 235M 0 235M 0% /dev/shm
tmpfs tmpfs 235M 5.6M 229M 3% /run
tmpfs tmpfs 235M 0 235M 0% /sys/fs/cgroup
/dev/sda1 xfs 897M 127M 771M 15% /boot
tmpfs tmpfs 47M 0 47M 0% /run/user/0
172.20.20.100:/data/share/soft nfs4 36G 1.1G 35G 4% /root/soft
Problems encountered
[Root @ node200 ~] # showmount -e 172.20.20.100
clnt_create: RPC: Port mapper failure - Unable to receive: errno 113 (No route to host)
Because iptables rules did not add due, the solution:
First, turn off the firewall, this is not the whole ×××. Another iptables can add nfs to all ports
As used herein, the first method:
systemctl stop firewalld.service
service iptables stop
Related parameters:
| parameter |
Explanation |
| ro |
Read-only access |
| rw |
Read and write access |
| sync |
All data written in the shared request |
| async |
nfs in response to the request before the data can be written |
| secure |
nfs security by 1024 following TCP / IP port to send |
| insecure |
By transmitting the above nfs port 1024 |
| wdelay |
If multiple users want to write nfs directory, the grouping write (default) |
| no_wdelay |
If multiple users want to write nfs directory, write immediately, when using async, you do not need this setting |
| hide |
Does not share its subdirectories nfs shared directory |
| no_hide |
Nfs shared directory subdirectories |
| subtree_check |
If you share a subdirectory / usr / bin and the like, nfs inspection authority to force the parent directory (the default) |
| no_subtree_check |
Do not check the parent directory permissions |
| all_squash |
UID and GID mapping file sharing anonymous user anonymous, for public directory |
| no_all_squash |
Reserved share files UID and GID (default) |
| root_squash |
All root user requests as mapped to the same anonymous user rights (default) |
| no_root_squash |
Full administrative access to the root user with root directory |
| anonuid = xxx |
Specify nfs server / etc / passwd file in the anonymous user's UID |
| anongid=xxx |
Specify nfs server / etc / passwd file in the anonymous user's GID |