Category: RHEL7

NFS Server Configuration RHEL 7 / Cent OS 7

Using NFS server will share the files/ Directories over the network.
Using this service will install operating system and access the remote server directory/file to read/write files and will share the file/directory to other machines.

Required Package:

libnfsidmap-0.25-15.el7.x86_64
nfs-utils-1.3.0-0.33.el7.x86_64

Installing NFS packages:

Use the below command to install all the required packages in one shot.

#yum install nfs*

 

Check whether the packages are installed by executing below command

[root@server ~]# rpm -qa | grep nfs
libnfsidmap-0.25-15.el7.x86_64
nfsometer-1.7-1.el7.noarch
nfs4-acl-tools-0.3.3-15.el7.x86_64
nfs-utils-1.3.0-0.33.el7.x86_64
nfstest-2.1.1-0.0.el7.noarch

Important configuration files:

/etc/exports :                This file contains which all are exported to remote                                                                 machines 
/etc/host.allow :           Daemon/ Client which matches the entry available in                                                        this file, will be granted access.
/etc/host.deny :           Access is denied for daemon/ client which matches in                                                     this file.
/etc/fstab :                      Will mount the shared directories/ filesystems                                                                   permanently using this file.
/etc/sysconfig/nfs:  Will manage the nfs port using this file.

Services which need to be enabled and started:

rpcbind  service
nfs-server  service

Command to enable the services:

#systemctl enable rpcbind
#systemctl enable nfs-server

[root@server ~]# systemctl enable rpcbind
[root@server ~]# systemctl enable nfs-server
Created symlink from /etc/systemd/system/multi-user.target.wants/nfs-server.service to /usr/lib/systemd/system/nfs-server.service.

Command to start the services:

#systemctl start rpcbind
#systemctl start nfs-server

[root@server ~]# systemctl start nfs-server

[root@server ~]# systemctl start rpcbind

create directory for sharing:

[root@server ~]# mkdir /nfshare

set the all permission to all

#chmod 777 /nfshare

Now share the directory using NFS by mentioning the directory details in /etc/exports file

#vi /etc/exports

/nfsfileshare 192.168.12.7(rw,sync,no_root_squash)

save and exit from the file

Now use the below command to make it available in network as a shared directory

[root@server ~]# exportfs -r

Enable the services permanently in firewall in this session

[root@server ~]# firewall-cmd --permanent --zone public --add-service  mountd
success
[root@server ~]# firewall-cmd --permanent --zone public --add-service rpc-bind
success
[root@server ~]# firewall-cmd --permanent --zone public --add-service nfs
success

reload the firewall  changes and make effect in this session by executing below command

[root@server ~]# firewall-cmd --reload
success

 

Now all the configuration has been done in server side and have to check and mount the shared directory in client machine.

showmount command will help us to list the directory which is shared from remote machine.

[root@node1 ~]# showmount -e 192.168.43.226
Export list for 192.168.43.226:
/nfshare *

Now we need to mount the shared directory in client. Before that we should create a directory to use that as a mount point.

[root@node1 ~]# mkdir /nfsmount

Mount the directory temporarily

#mount 192.168.43.226:/nfshare  /nfsmount

Mount permanently by editing /etc/fstab file and make entry

#vi /etc/fstab
192.168.43.226:/nfshare/ /nfsmount nfs rw,sync 0 0

save and exit from the file.

unmount the directory because we mounted temporarily before restart and after restart issue mount to check whether the shared directory is listing or not. If its not listing then there is an issue with entry in /etc/fstab file.

#umount /nfsmount

Restart the client and check using mount command

[root@node1 ~]# mount | grep /nfsmount
192.168.43.226:/nfshare/ on /nfsmount type nfs (rw,sync,vers=4,addr=192.168.43.226,clientaddr=192.168.43.67)

Configuring SAMBA Server in RHEL7/ Cent OS 7

We are going to learn how to configure SAMBA Server in RHEL7 / Cent OS  7. Its used to share file and printer sharing over the network.

Now a days its used as Domain controller like Windows Active Directory.

Will integrate SAMBA Server with Windows Domain as a Primary domain controller or as a domain member.

Operating System:  RHEL7
Host Name:   server
IP Address:  192.168.43.226 / 255.255.255.0

Port numbers for Samba server :
137/tcp
137/udp
138/tcp
138/udp
139/tcp
139/udp
445/tcp
445/udp
Daemons:
  1. smbd: This is for file and printer sharing services
  2. nmbd:  This is for NetBIOS to IP Address service and Mapping NetBIOS Compluter Name to the TCP/IP IP Addresses.
Installing SAMBA Server:
 
#yum install –y samba samba–commons cups–libs policycoreutils–python samba–client
Below command will install all the packages which is required for samba server configuration.
 [root@server ~]# yum install -y samba
 
Create directory for sharing:
 
[root@server ~]# mkdir /sharedir
Create a new group called samba
 
#groupadd samba
 [root@server ~]# groupadd samba
 
 

change the group and permission for the directory which we are going to share using samba

[root@server ~]# chgrp -R samba /sharedir
[root@server ~]# chmod -R 777 /sharedir


check for the existing group and permission details for the directory.

[root@server ~]# ll / | grep sharedir
drwxrwxrwx. 2 root samba 6 Nov 11 08:59 sharedir
Now change the group and permission for the directory

Now again check for the group and permission for the directory and it’s changed.

Create a new user called test and add it to our newly created group which is called samba. Then set the samba password for the user.


[root@server ~]# useradd smbuser
[root@server ~]# usermod -G samba smbuser
[root@server ~]# smbpasswd -a smbuser
New SMB password:
Retype new SMB password:
Added user smbuser.
For samba default configuration file is /etc/samba/smb.conf 


We are going to edit this configuration file. Before that its advisable to take backup of configuration file.

#cp -p /etc/samba/smb.conf  /etc/samba/smb.conf.bkp


now we will edit the smb.conf file

[root@server ~]# vi /etc/samba/smb.conf
make the below entries at end of line.
Comment:   This will explain the operation what we are doing like sharing directory or sharing printer.
Path:           We are going to share a directory. So, here we should mention the directory with absolute path
Valid users:  Here we can mention the users and groups who has permission to access this directory.
Writeable:    i am giving yes, because i need read and write both permission.
browseable:  If you want to access the shared things using browser, we can make it as yes
Public:          We are not going to share this directory for all users. So, we should use no option.
[sharedir]
 comment = shared-directory
 path = /sharedir
 valid users = smbuser, @samba
 writeable = yes
 browseable = yes
 read only = no
 inherit acls = Yes

In the same smb.conf  file we should add our interface name and IP Address to allow the network in samba server.

And one more entry is very important that we need to mention our windows machines workgroup name. First we will use default one. If the windows machines are falling under different workgroup name. Then we have to change the workgroup name in this configuration file.

WORKGROUP  =  MYGROUP

We can add the services in /etc/services file.


[root@server ~]# vi /etc/services
netbios-ns 137/tcp # netbios name service
netbios-ns 137/udp # netbios name service
netbios-dgm 138/tcp # netbios datagram service
netbios-dgm 138/udp # netbios datagram service
netbios-ssn 139/tcp # netbios session service
netbios-ssn 139/udp # netbios session service


Now start the samba service and enable the service permanently on this run level.

[root@server ~]# systemctl start smb.service
[root@server ~]# systemctl enable smb.service
Created symlink from /etc/systemd/system/multi-user.target.wants/smb.service to /usr/lib/systemd/system/smb.service.

Same like that start and enable nmb service.

#systemctl start nmb.service
#systemctl enable nmb.service



 Add the firewall rule to allow the samba service via firewall.
In RHEL 7 firewall has been shipped from iptables to firewalld.

[root@server ~]# systemctl start firewalld
[root@server ~]# firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="192.168.56.0/24" service name="samba" log prefix="samba" level="info" limit value="1/m" accept'
success
[root@server ~]# systemctl enable firewalld Created symlink from /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service to /usr/lib/systemd/system/firewalld.service.
Created symlink from /etc/systemd/system/basic.target.wants/firewalld.service to /usr/lib/systemd/system/firewalld.service.



Then reload the firewall configuration using below command

[root@server ~]# firewall-cmd --reload
success

Now all the configuration has been completed and will check in windows machine whether the samba is working well or not.

Connecting SAMBA server from linux  client machine.

samba client should be installed in linux client machine.

Package: samba-client-4.4.4-9.el7.x86_64

#yum install samba-client*

[root@server ~]# smbclient -L 192.168.43.126 -U test


-L :    This option will list the shared directories
192.168.43.226 :  IP Address of samba server
-U :  Option to mention the user name next to this which has access to this shared directory.

Output should be like below

Accessing via samba console:

#smbclient //192.168.43.226/sharedir -U test

above command will help you to show the content of shared directory and to do operations over their.



We successfully configure SAMBA server. Thanks for the support. 


Configuring DHCP Server in RHEL7/ Cent OS 7

DHCP – Dynamic host configuration protocol

We are going to configure DHCP Server in RHEL7

It’s a network protocol used to assign IP’s to the client dynamically over the network.

DHCP Workflow:

Required Package installation:

#yum install dhcp

Now we should assign a insterface in DHCPDARGS in /etc/sysconfig/dhcpd

 [root@localhost ~]# vi /etc/sysconfig/dhcpd
 
  DHCPDARGS=enp0s3

After installing package it will create one empty configuration file /etc/dhcp/dhcpd.conf  and we have one sample configuration file under /usr/share/doc/dhcp-4.2.15/dhcpd.conf.exmaple.

So as first, append the content from example file to original file using cat command.

[root@localhost ~]# cat /usr/share/doc/dhcp-4.2.5/dhcpd.conf.example >> /etc/dhcp/dhcpd.conf

Open the configuration file to configure DHCP Server:

First will give basic configuration which will be common for your network.

[root@localhost ~]# vi /etc/dhcp/dhcpd.conf


Make the below entries 

 option domain-name "lbcdomain.com";
 option domain-name-servers server.lbcdomain.com;
 default-lease-time 600;
 max-lease-time 7200;
 authoritative;
 log-facility local7;



Now make subnet details in same configuration file.

subnet 192.168.1.0 netmask 255.255.255.0 {
 option routers 192.168.1.254;
 option subnet-mask 255.255.255.0;
 option domain-search "lbcdomain.com";
 option domain-name-servers 192.168.1.1;
 option time-offset -18000; # Eastern Standard Time
 range 192.168.1.10 192.168.1.100;
}

Optional(To reserve IP for a dhcp client machine) :

If you wan to assign a static IP to a client using DHCP service, use the below command.

host station1 {
 option host-name "node11.lbcdomain.com";
 hardware ethernet 00:12:2A:2B:3C:AB;
 fixed-address 192.168.1.100;
}

Restart the dhcp service now to complete the DHCP server configuration.

[root@localhost ~]# systemctl restart dhcp
To check dhcp we should login in client machine which is in same network physically and edit the interface configuration file to make dhcp ip assigned.
#vi /etc/sysconfig/network-scripts/ifcfg-eth0
 change the entry for BOOTPROTO as dhcp

DEVICE=eth0

BOOTPROTO=dhcp

TYPE=Ethernet

ONBOOT=yes
 
Save and quit.
 
Now restart the network service.
 #service network restart
 
now check for the ip and it should be assigned in between 192. 168.1.50 to 192.168.1.254
  
DHCP Configuration has been done.
Do practice well. All the best.

Changing/ Recovering root user password in RHEL7/ Cent OS 7

We are going to see How to Changing/ Recovering root user password in RHEL7/ CentOS 7 in this post

Boot the system and wait for GRUB menu. On some Operating systems, you need to disturb the booting by pressing any keys in your system.

Changing/ Recovering root user password in RHEL7/ Cent OS 7
Highlight the first line which is pointing the Operating System entry like showed in the above image and press “e” key in your keyboard to edit manually.
Then will get the below screen.
Using up/down, left/right arrow keys move the cursor to the “rhgb quiet” which is in kernel line starting with “linux16”
Using delete/backspace keys manually delete “rhgb quiet” entry and append “init=/bin/bash” entry like below.

Than press Ctrl+x  to reboot your OS with specified option. Once rebooted, will get a shell prompt without credentials.

check whether the root filesystem has been mounted or not.

Mount the root filesystem with RW permission.

Now issue the “passwd” command to recover/change the root password. It will ask for the new password and re-enter the password for confirmation. Once provided the new password will receive the “Authentication token successfully updated”

Relabel the SELinux content using below command.
Restart the machine using the below command.
Finally, we recovered the root password. Now will restart the machine and login with a new root password.

Configuring LVM in redhat

For LVM Configuration need to follw the below steps.

1. Partition creation
2. Physical volume creation
3. Volume group creation
4. Logical volume creation

Here i’m using /dev/sda and /dev/sdb hard disks

Size:

/dev/sda – 500GB
/dev/sdb – 500GB

I already shared the steps to create partitions in previous post.

Click here to create new partition/filesystem in a physical disk.

Using fdisk we have to change the partition type by changing the ID.

For that we should use “t” option to change the partition type. Once we executed this, it will ask for
the Hex code of partition type. Here we need to mention “8e” as Hex code for LVM partition type.

Note: change the partition type for all HDD/ Partitions which we are going to configure LVM.

Than follow the below steps for LVM configuration.

Next we have to create physical volumes using below mentioned commands.

#pvcreate /dev/sda1 /dev/sdb1


#vgcreate -s 16M newvg /dev/sda1 /dev/sdb1

“newvg” is new volume group name and /dev/sda1, /dev/sdb1 will be added in this volume group.
Now this two hard disks will act as a single hard disk and the new size of hard disk is 1000GB.

Next we have to create logical volumes over the volume group, which is like a partitioning here.

#lvcreate -n lv1 -L 200G newvg

-n:  This option is to mention the new logical volume group.
lv1: new logical volume group name.
-L:  this option is to mention the size of new logical volume.

Now we have created logical volume and we should format and mount the lv.

#mkfs.xfs /dev/newvg/lv1

directory is required to mount the lv.

#mkdir /data

#mount /dev/newvg/lv1 /data


Now we successfully configured LVM. Follow the lvcreate steps to create more lv’s.