CloudLinux

How to Change Hostname on CentOS or Cloudlinux?


In order to change the your CentOS or Cloudlinux hostname permanently, you need to edit two files. The files are

  • /etc/sysconfig/network
  • /etc/hosts

Prior to changing the hostname, it is wise to check the existing hostname.

1. To do this issue the following command after SSH to you server

hostname

For example, my hostname is “host.domain.net”

2. Once completed, edit “/etc/sysconfig/network” file by issuing the following command

nano /etc/sysconfig/network

The example output as below,

NETWORKING="yes"
NETWORKING_IPV6="no"
GATEWAYDEV="eth0"
HOSTNAME=host.domain.net
DOMAINNAME=domain.net

3. Look for “HOSTNAME=host.domain.net”, and change to your desire hostname and save the file. Take note on the “hostname” format. It must be fully qualified domain name (FQDN).

4. Next, edit “/etc/hosts” file by issuing the following command

nano /etc/host

The example output as below,

127.0.0.1 localhost
88.88.88.88 host.domain.net

5. Again, look for “host.domain.net”, and change to your desire hostname as above and save the file.

6. Finally, and then rebooting the system

reboot

 

How to Modify CloudLinux LVE Limit


I’m using CloudLinux as server OS in OnApp Cloud Platform. Although I’m the only user in the server, I like CloudLinux for system stability as my website regularly under DOS/DDOS attack. However, I would like to use the resource as much as possible & not the default setting.

The best way to control LVE limits is using LVE Manager or lvectl command line tool. The limits are saved in /etc/container/ve.cfg. In other word, we can modify this file directly to modify limit.

Below is the sample of ve.cfg

<?xml version="1.0" ?>
<lveconfig>
	<defaults>
		<cpu limit="25"/>
		<ncpu limit="1"/>
		<io limit="1024"/>
		<mem limit="262144"/>
		<other maxentryprocs="20"/>
		<pmem limit="262144"/>
		<nproc limit="0"/>
	</defaults>
	<lve id="501">
		<cpu limit="95"/>
		<ncpu limit="4"/>
		<io limit="102400"/>
		<mem limit="524288"/>
		<other maxentryprocs="100"/>
		<pmem limit="524288"/>
		<nproc limit="100"/>
	</lve>
</lveconfig>

For the user id, 501 the resource allocated is as follow

<cpu limit="95"/>			-> CPU usage limit is 95%
<ncpu limit="4"/>			-> Number of CPU limit is 4
<io limit="102400"/>			-> IO limit is 102400 kB/s
<mem limit="524288"/>			-> Virtual memory limit is 524288 kB
<other maxentryprocs="100"/>		-> Number of Entry Processes limit is 100
<pmem limit="524288"/>			-> Physical Memory limit is 524288 kB
<nproc limit="100"/>			-> Number of Processes limit is 100

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