If you want to see the list of users who are logged in server and their IP and what they are doing, here is how you can do.
Login to your server as root and run following command.
w
OR
who
Above command will list all logged in users, their IP, what they are doing.
If for some reason you do not want to update your server kernel but want to update other packages running on CentOS, here is how you can do.
Update can be done using yum command and to exclude kernel from update we need to add exclude command.
Login to your server as root via SSH and run following command:
yum -y --exclude=kernel\* update
OR
yum -y -x 'kernel*' update
Above command will update all packages but will leave kernel update on a CentOS server.
For security reason, it is recommended that you disable directory listings / indexing on your server. Apache default configuration comes with this feature enabled but its always a good idea to get it disabled unless you really need it.
When this option is enabled, user can see the list of files / folder of a directory when no index file is present.
With Apache listings / indexing option disabled, user will not be able to see content of a directory in absence of a index file.
Here is how you can disable this on a cPanel server.
Login to your server WHM as root.
Navigate to:
WHM Main >> Service Configuration >> Apache Configuration >> Global Configuration
Under Directory ‘/’ Options >> uncheck Indexes >> Save >> Restart Apache
Done!!
You have moved your WordPress website to a new server / hosting provider, and all pages on your WordPress website are giving 404 page not found error. This solution may fix your problem.
Login in WordPress Admin Dashaboard and navigate to:
And click Save changes button with same settings.
Check your website now. That should solve your problem.
This tutorial explains how you can start and stop firewall on a CentOS / RedHat Linux server.
Below commands will stop / disable firewall of a redhat / centos server. Login to your server as root via SSH and run following commands:
service iptables save service iptables stop chkconfig iptables off
For IPv6 firewall, use below commands:
service ip6tables save service ip6tables stop chkconfig ip6tables off
Run below commands to start firewall.
chkconfig iptables on service iptables start
For IPv6 firewall, use below commands:
chkconfig ip6tables on service ip6tables start
This tutorial explains how you can list all current iptables rules on a RedHat / CentOS Linux server, and how you can clear / flush current iptables rules.
Below command will list of current iptables rules of your CentOS / RedHat Linux server.
iptables -L
Use below command to delete / clear / flush all current iptables rules of your CentOS / RedHat Linux server.
iptables -F
If your server went down after flushing iptables, please refer to following tutorials:
Solution – Server Down after Flushing IPtables
This tutorial explains how you can start, stop and restart iptables rules of your server firewall. This tutorial is applicable for CentOS / RedHat Linux servers.
service iptables start
OR
/etc/init.d/iptables start
service iptables stop
OR
/etc/init.d/iptables stop
service iptables restart
OR
/etc/init.d/iptables restart
Recently one of my vps (CentOS) went down after flushing / clearing iptables rules using below command:
iptables -F
The above command will flush/clear all current firewall rules of your CentOS / Linux server.
Here is how I fixed it. I just restarted iptables rules using below command and my VPS was UP.
service iptables restart
You can also use below command to restart iptables rules.
/etc/init.d/iptables restart
If you want to copy a file / folder from one server to another, you can use wget or scp command. In this tutorial I will show how to use scp command to copy files / folder from one server to another.
Server One IP is: 1.1.1.1
Server Two IP is: 2.2.2.2
Suppose you want to copy a file from server one to server two.
Location of file on server one is: /home/filename.txt
Login to server two via SSH and run following command
scp root@1.1.1.1:/home/filename.txt /home/
This will copy filename.txt file from server one to server two and save in /home directory.
Suppose you want to copy a complete folder from server one to server two.
Let’s say you want to copy /backup folder from server one to server two.
Login to server two via SSH and run following command
scp -r root@1.1.1.1:/backup /foldername
This will copy /backup directory from server one to server two and save in /foldername directory.
We can test server disk read / write speed from SSH. Below command will show the speed that the server can read and write a 1GB file.
Login to your server via SSH and run below command:
dd if=/dev/zero of=sb-io-test bs=1M count=1k conv=fdatasync
Higher scores is better.
SSD disk will give you very fast read / write speed compared to SATA disks. There are many providers offering SSD VPS like DigitalOcean, RamNode etc
