CentOS 7 only allows Fully Qualified Domain Names (FQDN’s). Acceptable values include lower-case letters a to z, numbers 0 to 9, the period, and the hyphen, and between 2 and 63 characters.
At the console, type:
hostnamectl set-hostname my.new-hostname.server
NOTE: Replace my.new-hostname.server with your chosen hostname.
Check the Hostname
In this tutorial, I use the hostname server1.example.com with the IP p 192.168.1.100. These settings might differ for you, so you have to replace them where appropriate.
I will add the EPEL repo here to install latest phpMyAdmin as follows:
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY*
yum -y install epel-release
To edit files on the shell, I’ll install the nano editor. If you prefer vi for file editing, then skip this step.
yum -y install nano
Installing MySQL / MariaDB
MariaDB is a MySQL fork of the original MySQL developer Monty Widenius. MariaDB is compatible with MySQL and I’ve chosen to use MariaDB here instead of MySQL. Run this command to install MariaDB with yum:
yum -y install mariadb-server mariadb
Then we create the system startup links for MySQL (so that MySQL starts automatically whenever the system boots) and start the MySQL server: Continue reading “Install LAMP on Centos 7 with PHP 5.x/7.0/7.1/7.2” »
MariaDB is an open source relational database management system, backward compatible, binary drop-in replacement of MySQL. It is developed by some of the original developers of the MySQL and by many people in the community. With the release of CentOS 7, MySQL was replaced with MariaDB as the default database system.
If you, for any reason need to install MySQL, check the How to Install MySQL on CentOS 7 tutorial. If your application does not have any specific requirements, you should stick with MariaDB, the default database system in CentOS 7.
In this tutorial we will show you how to install the latest version of MariaDB on CentOS 7 using the official MariaDB repositories.
Make sure you are logged in as a user with sudo privileges before proceeding with the tutorial. Continue reading “Install MariaDB on CentOS 7” »
If you are looking for the options to avoid any DNS-related downtime or the way to manage dns across all server you have, you might consider to set up dns cluster.
Create user dns-cluster on a server which will be used as dns slave
On the second server (slave) with vestacp you should create new user with name dns-cluster (via gui or cli)Code:
v-add-user dns-cluster passowrd email@example.com
On the first server (master) you should run this command: Continue reading “Vesta- How to set up master-slave DNS cluster” »
I had few issues on my container and KVM on installing vestacp. Issues were like quite weird, such as-
- Post installation on KVM- it moved into emergency maintenance mode
- Post installation on LXC container- DNS resolution halted
After hours and hours of search, found few root causes-
- I have to withdraw quota with vestacp installation package
- No firewall on LXCcontainer
So let’s start.
Download installation script
curl -O http://vestacp.com/pub/vst-install.sh
bash vst-install.sh --nginx yes --phpfpm yes --apache no --named yes --remi yes --vsftpd yes --proftpd no --iptables no --fail2ban no --quota no --exim yes --dovecot yes --spamassassin yes --clamav yes --softaculous yes --mysql yes --postgresql no --hostname yourdomain.com --email firstname.lastname@example.org --password yourpassword
You can also generate your installation command from vesta website: Continue reading “Install Vesta Control Panel (vestacp) on Centos 7 with PHP-FPM and PHP 7.2” »
To use RHEL/CentOS 6 system as an iSCSI initiator or client, you must have iscsi-initiator-utils package installed. You can verify that this is installed on your system using the rpm command, as shown in the following example:
$ rpm -qa | grep iscsi-initiator-utils
Install the package if its not already available on your system using yum.
# yum install iscsi-initiator-utils
Start the iscsi demaon and use chkconfig to enable it to start after reboot as well.
# service iscsi start
# chkconfig iscsi on
Once you have installed the required package and started the service you can start discovering the available targets. To Obtain a listing of available targets from a given host (please note that ipaddress listed below must be replaced with the resolvable hostname or IP address of the system providing the port if different than default):
# iscsiadm -m discovery -t st -p 192.168.10.10
Continue reading “Configure iSCSI Initiator (client) in CentOS / RHEL 6” »
Device Mapper Multipathing (DM-Multipath) is a native multipathing in Linux, Device Mapper Multipathing (DM-Multipath) can be used for Redundancy and to Improve the Performance. It aggregates or combines the multiple I/O paths between Servers and Storage, so it creates a single device at the OS Level.
For example, Lets say a server with two HBA card attached to a storage controller with single ports on each HBA cards. One lun assigned to the single server via two wwn number of both cards. So OS detects two devices: /dev/sdb and /dev/sdc. Once we installed the Device Mapper Multipathing. DM-Multipath creates a single device with a unique WWID that reroutes I/O to those four underlying devices according to the multipath configuration. So when there is a failure with any of this I/O paths, Data can be accessible using the available I/O Path.
Install the Device Mapper Multipath package.
Verify the device-mapper-multipath package has been installed or not.
[root@linux1 ~]# rpm -q device-mapper-multipath
If it is not installed, Install the Device Mapper Multipath package using yum to avoid dependencies issue. if yum is not configured, please refer the link Yum Configuration on Linux.
[root@linux1 ~]# yum -y install device-mapper-multipath
Basic Configuration of Linux Device Mapper Multipathing
Configuration file is /etc/multipath.conf file, take a backup of it. Edit the configuration file to ensure you have the following entries uncommented out. Continue reading “Add Multipath and connect to XFS system” »
Allow IP forwarding
(Note: if your testing this on the same box your doing this on it won’t work, you need at least 3 machines to test this out, virtual ones work nicely)
First we enable ipv4 forwarding or this will not work:
# echo "1" > /proc/sys/net/ipv4/ip_forward
# sysctl net.ipv4.ip_forward=1
next we add a filter that changes the packets destination ip and allows us to masquerade:
# iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to-destination 10.0.0.3:80
# iptables -t nat -A POSTROUTING -j MASQUERADE
The above filter gets added to iptables PREROUTING chain. The packets first go through the filters in the PREROUTING chain before iptables decides where they go. The above filter says all packets input into eth0 that use tcp protocol and have a destination port 80 will have their destination address changed to 220.127.116.11 port 80. The DNAT target in this case is responsible for changing the packets Destination IP address. Variations of this might include mapping to a different port on the same machine or perhaps to another interface all together, that is how one could implement a simple stateful vlan (in theory). Continue reading “Stateful Load Balancer with iptables and NAT” »
For example, you need to assign the IP range 192.168.10.6 – 192.168.10.100 to your eth0 interface.
Create a range file in /etc/sysconfig/network-scripts/ifcfg-eth0-range0 as below
CLONENUM_START is the number that will be assigned to the first IP alias interface (eth0:1 in this example).
If you need to add more ranges of IPs then just use a different file for eg. ifcfg-eth0-range1, for each one of the ranges. Make sure CLONENUM_START does not overwrite other aliases.
Once you have configured the range/s of IPs you just need to restart the network service in order to activate it
In the event your Linux box experiences disk or file system issues you may receive a “Give root password for maintenance” prompt upon reboot. If you have your root password you can login but in the event your using ‘slide’ or ‘sudo’ for wheel access or you’ve just mis-placed your root password – you’ll need to reset it.
To reset your root password:
- When the GRUB loader shows during boot press the spare bar to pause boot.
- Select your boot kernel.
- Type ‘e’ to edit the default kernel line.
- Type ‘e’ again on the line that starts with ‘kernel’.
- Add ‘init=/bin/bash’ to the end of the ‘kernel’ line then press enter.
- Type ‘b’ to boot the modified kernel parameters.
- Once you’re at the /bin/bash prompt you will need to remount the root file system as read/write in order to edit the passwd file:
# mount -o remount,rw /
- Change your root password:
# passwd root
- Remount the filesystem back to read only:
# mount -o remount,ro /
- Reboot your server using CTR-ALT-DELETE.
- You will now be able to login with your new root password and carry out the maintenance.