13 Jun 2020

How to install KVM for Virtualization in LinuxMint

This article shows you, how to install KVM in Linux Mint for Virtualization

Contents:

1. Install qemu-kvm and libvirt
2. Add user to libvirt group
3. Remote access via SSH
4. Add a pool for ISO file

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1. Install qemu-kvm and libvirt

Use the following command to install qemu-kvm package and some packages for virtual machine operation.

$ sudo apt install -y -o 'apt::install-recommends=true' \
  qemu-kvm libvirt0 libvirt-bin virt-manager libguestfs-tools

2. Add user to libvirt group

This command for the user in libvirt group can run virt-manager and virsh without sudo.

$ sudo gpasswd libvirt -a <username>
$ sudo reboot

3. Remote access via SSH

Following command for virt-manager and virsh provdes remote access via SSH. If you want to use SSH public key authentication, you can omit inputting password.

Create SSH keys on client, which use remote access via SSH.

$ ssh-keygen -t rsa -f ~/.ssh/id_rsa -N ""
Generating public/private rsa key pair.
Your identification has been saved in /home/idatahost/.ssh/id_rsa.
Your public key has been saved in /home/idatahost/.ssh/id_rsa.pub.
<snip>
$ cat ~/.ssh/id_rsa.pub
ssh-rsa AAAAB... [email protected]

Now add SSH public key entry to ~/.ssh/authorized_keys on server which is installed KVM.

$ cat ~/.ssh/authorized_keys
ssh-rsa AAAAB... [email protected]

Now specify server URI with -c option on client.

$ virsh -c qemu+ssh://[email protected]/system

Setting server URI to VIRSH_DEFAULT_CONNECT_URI is equal with specifying server URI with -c option. Write VIRSH_DEFAULT_CONNECT_URI settings in your .bashrc if you need.

$ export VIRSH_DEFAULT_CONNECT_URI=qemu+ssh://[email protected]/system
$ virsh

4. Add a pool for ISO file

Create ISO directory and define as pool.

$ sudo mkdir /var/lib/libvirt/isos
$ virsh pool-define-as isos dir - - - - /var/lib/libvirt/isos
$ virsh pool-autostart isos
$ virsh pool-start isos
11 Jun 2020

406 Error [Not Acceptable An appropriate..]

Not Acceptable
An appropriate representation of the requested resource could not be found on this server.
406 Error in DirectAdmin

That would be because false-positive ModSecurity rules are being hit. You may either try changing ModSecurity ruleset or disabling ModSecurity altogether, for example, to change ModSecurity ruleset from owasp to comodo, execute the following commands:

cd /usr/local/directadmin/custombuild
./build set modsecurity yes
./build set modsecurity_ruleset comodo
./build modsecurity

Additionally you might need to run
For Apache

./build apache
./build rewrite_confs

For Nginx

./build nginx
./build rewrite_confs

How to Disabled ModSecurity altogether

cd /usr/local/directadmin/custombuild
./build set modsecurity no
./build set modsecurity_ruleset comodo
./build modsecurity

Additionally you might need to run:
For Apache:

./build apache
./build rewrite_confs

For Nginx

./build nginx
./build rewrite_confs
09 Jun 2020

How to install ClamAV in DirectAdmin Linux Server

*** Note *** Technical support for ClamAV is very limited. Use at your own risk.

To install ClamAV:

1) Install the binaries:

cd /usr/local/directadmin/custombuild
./build update
./build set clamav yes
./build clamav

If you’re running CustomBuild 2.0 exim.conf changes are not required, as it uses .include_if_exist options in the exim.conf.  Skip to Step 4.

2) Edit your /etc/exim.conf, and add the following before “primary_hostname  =”:

av_scanner = clamd:127.0.0.1 3310

Skip this step (#2) if you are running CustomBuild 2.0, as it adds this for you with /etc/exim.clamav.load.conf.

3) Restart Exim

<pre>systemctl restart exim</pre>

09 Jun 2020

What is ModSecurity and How to Enable ModSecurity in DirectAdmin

Overview

With over 70% of all attacks now carried out over the web application level, organizations need every help they can get in making their systems secure. Besides ModSecurity antivirus can help to reduce malware. For linux server ClamAV/Maldet antivirus enough good. You can follow the post

“How to install ClamAV antivirus on DirectAdmin Linux server”

“How to install ClamAV antivirus on DirectAdmin Linux server and scan public_html folder”

Web application firewalls are deployed to establish an external security layer that increases the protection level, detects and prevents attacks before they reach web-based software programs.

ModSecurity is an open-source web-based firewall application (or WAF) supported by different web servers: Apache, Nginx and IIS.

Usage

The module is configured to protect web applications from various attacks. ModSecurity supports flexible rule engine to perform both simple and complex operations. It comes with a Core Rule Set (CRS) which has various rules for:

  • cross website scripting
  • bad user agents
  • SQL injection
  • trojans
  • session hijacking
  • other exploits

To enable ModSecurity:

cd /usr/local/directadmin/custombuild
./build set modsecurity yes
./build set modsecurity_ruleset owasp
./build modsecurity

Additionally you might need to run

For Apache:

./build apache
./build rewrite_confs

For nginx:

./build nginx
./build rewrite_confs

 

08 Jun 2020

How to Fix “failed to mount /etc/fstab” Error in Linux

In this article, i will explain how to solve “failed to mount /etc/fstab” boot error in Linux. The file in question contains descriptive information concerning the filesystems the system can mount automatically at boot time.

This information is static and is read by other programs on the system such as mount, umount, dump and fsck. It has six important filesystem mount specification fields: the first field describes the block special device or remote filesystem to be mounted, the second field defines the mount point for the filesystem and the third specifies the filesystem type.

The fourth field defines the mount options associated with the filesystem, and the fifth field is read by dump tool. The last field is used by fsck tool to establish the order of filesystem-checks.

After editing the /etc/fstab to create an automount and rebooting my system; it booted into emergency mode showing the error message below.

Linux Emergency Mode

I logged in as root from the interface above, and typed the following command to look through the systemd journal; then I saw the errors shown in the screen shot (indicated using red).

As you can see, the main error (failure of etc-fstab.mount unit) lead to several other errors (systemd unit dependency issues) such as failure of local-fs.target, rhel-autorelabel-mark.service etc.

# journalctl -xb

 

Boot Error Messages

Causes of “failed to mount /etc/fstab” Error in Linux

The error above may result from any of the issues below, in the /etc/fstab file:

  • missing /etc/fstab file
  • wrong specification of filesystem mount options,
  • failing mount points or
  • unrecognized characters in the file.

To solve it, you can use the original file if you created a backup, otherwise comment out any changes you made using the “#” character (and also ensure that all the uncommented lines are filesystem mount lines).

So I opened the /etc/fstab using vi/vim/nano text editor to check for any errors.

# vi /etc/fstab

Linux /etc/fstab File

I realized I had typed an “r” letter at the beginning of the file as shown in the screen shot above – this was recognized by the system as a special device which did not actually exist in the filesystem, thus resulting to the sequential errors shown above.

This took me several hours before noticing and fixing it. So I had to remove the letter, commented out the first line in the file, closed and saved it. After running a reboot, the system booted well again.

How to Avoid Such Issues in the Future

To avoid encountering such issues on your system, take note of the following:

Always create a backup of your config files before editing them. In case of any errors in your configs, you can revert to the default/working file.

For instance:

# cp /etc/fstab /etc/fstab.orig

Secondly, check config files for any errors before saving them, certain applications offer utilities to check syntax of config files before running the application. Use these utilities where possible.

However, if you happen to get any system errors messages:

First look through the systemd journal using the journalctl utility to determine what exactly caused them:

# journal -xb

If you can’t resolve the errors in one way or the other, run to any of the millions of Linux forums on the web and post the issue there.

08 Jun 2020

How to Boot into Single User Mode in CentOS/RHEL 7

Single User Mode (sometimes known as Maintenance Mode) is a mode in Unix-like operating systems such as Linux operate, where a handful of services are started at system boot for basic functionality to enable a single superuser perform certain critical tasks.

It is runlevel 1 under system SysV init, and runlevel1.target or rescue.target in systemd. Importantly, the services, if any, started at this runlevel/target varies by distribution. It’s generally useful for maintenance or emergency repairs (since it doesn’t offer any network services at all), when a computer is not capable of normal operations.

Some of the low-level repairs include running such as fsck of damaged disk partitions, reset root password if you have lost it, fix “failed to mount /etc/fstab” error – just to mention the most critical of them. And also when the system fails to boot normally.

In this tutorial, we will describe how to boot into single user mode on CentOS 7. Note that practically this will help you enter the emergency mode and access an emergency shell.

How to Boot into Single User Mode

1. First restart your CentOS 7 machine, once boot process starts, wait for the GRUB boot menu to appear as shown in the screen shot below.

Centos7 password reset image

 

2. Next, select your Kernel version from the grub menu item and press e key to edit the first boot option. Now use the Down arrow key to find the kernel line (starts with “linux16“), then change the argument ro to rw init=/sysroot/bin/sh as shown in the screen shot below.

3. Once you have finished the task in the previous step, press Ctrl-X or F10 to boot into single user mode (access an emergency shell).

4. Now mount root (/) filesystem using the following command.

chroot /sysroot

At this point, you can perform all the necessary low-level system maintenance tasks. Once you are done, reboot the system using this command.

reboot -f

Thank you. Enjoy 🙂

04 Jun 2020

How To Reset Root Password On CentOS 7

CentOS7 is root password changing is totally different from CentOS 6. Now I going to show you how to reset root password in CentOS 7. This way also working for Citrix Xenserver Virtual Machine, KVM and other’s Virtual Machine platform. Even you can reset CentOS 7 password, if your server going to Emergency Maintenance mode.

Step 1: In the boot grub menu select option to edit

Press e

Centos7 password reset image

Step 2: Go to the line of Linux 16 and find out ro

Step 3: Now change ro with rw init=/sysroot/bin/sh

Step 4: Now press Control+x to start on single user mode

Step 5: Now access the system with this command

chroot /sysroot

Step 6: Reset the password.

passwd root

Step 7: Update selinux information

touch /.autorelabel

Step 8: Exit chroot

exit

Step 9: Reboot your system

reboot

That’s it 🙂 Enjoy! 🙂

01 Jun 2020

How to force WordPress site HTTP to HTTPS

Are you looking to move WordPress from HTTP to HTTPS and install an SSL certificate on your website? We have been getting a lot of requests on this topic because Google announced that Chrome browser will start marking all websites without SSL as insecure starting July 2018. In this article, we will show you how to properly move WordPress from HTTP to HTTPs by adding a SSL certificate.

Moving WordPress from HTTP to HTTPS / SSL

Don’t worry, if you have no idea what SSL or HTTPS is. We’re going to explain that as well.

What is HTTPS?

HTTPS or Secure HTTP is an encryption method that secures the connection between users’ browser and your server. This makes it harder for hackers to eavesdrop on the connection.

Every day we share our personal information with different websites whether it’s making a purchase or simply logging in.

In order to protect the data transfer, a secure connection needs to be created.

That’s when SSL and HTTPS come in.

Each site is issued a unique SSL certificate for identification purposes. If a server is pretending to be on HTTPS, and its certificate doesn’t match, then most modern browsers will warn the user from connecting to the website.

Insecure website warning

Now you are probably wondering, why do I need to move my WordPress site from HTTP to HTTPS specially if it’s a simple blog or small business website that doesn’t collect any payments.

Why do you need HTTPS and SSL?

Last year Google announced a plan to improve overall web security by encouraging website owners to make the switch from HTTP to HTTPS. As part of this plan, their popular Chrome web browser would mark all websites without a SSL certificate as “Not Secure” starting July 2018.

Chrome HTTP Not Secure

As part of the announcement, Google also said that websites with SSL will also see SEO benefits and higher rankings. Since last year, a large number of websites have switched from HTTP to HTTPS.

Google has been slowly rolling out the “Not Secure” warning in Chrome. For example, if someone visits a HTTP website using the incognito window, it will be marked as Not Secure. If someone visits a HTTP website on regular mode and tries to fill out a contact form or another form, then the website will be marked as insecure.

When your readers and customers see this notice, it gives them a bad impression for your business.

This is why all websites need to move form HTTP to HTTPS and install SSL immediately.

Not to mention, if you want to accept payments online on your eCommerce website, then you need SSL.

Most payment companies like Stripe, PayPal Pro, Authorize.net, etc will require you to have a secure connection before accepting payments.

We use SSL for our websites including iDataHost, FRA Technology, and BD SOFT IT.

Requirements for using HTTPS/SSL on a WordPress Site

The requirements for using SSL in WordPress is not very high. All you need to do is purchase an SSL certificate, and you might already have it for free.

The best WordPress hosting companies are offering free SSL certificates for all their users:

For more details, see our guide on how to get a free SSL certificatefor your WordPress website.

If your hosting company does not offer a free SSL certificate, then you’ll need to purchase an SSL certificate.

We recommend using idatahost.com because they offer the best SSL deal for both regular and wildcard SSL certificates.

By purchasing a SSL certificate from them, you also get a TrustLogo site seal for your website.

Once you have purchased an SSL certificate, you will need to ask your hosting provider to install it for you.

Setting up WordPress to Use SSL and HTTPs

After you have enabled SSL certificate on your domain name, you will need to set up WordPress to use SSL and HTTPs protocols on your website.

We will show you two methods to do that, and you can choose one that best fits your need.

Method 1: Setup SSL/HTTPS in WordPress Using a Plugin

This method is easier and is recommended for beginners.

First, you need to install and activate the Really Simple SSL plugin.

Upon activation, you need to visit Settings » SSL page. The plugin will automatically detect your SSL certificate, and it will set up your WordPress site to use HTTPs.

SSL enabled on a WordPress website

The plugin will take care of everything including the mixed content errors. Here’s what the plugin does behind the scenes:

  • Check SSL certificate
  • Set WordPress to use https in URLs
  • Set up redirects from HTTP to HTTPs
  • Look for URLs in your content still loading from insecure HTTP sources and attempt to fix them.

Note: The plugin attempts to fix mixed content errors by using output buffering technique. It can have a negative performance impact because it’s replacing content on the site as the page is being loaded. This impact is only seen on first-page load, and it should be minimal if you are using a caching plugin.

While the plugin says you can keep SSL and safely deactivate the plugin, it’s not 100% true. You will have to leave the plugin active at all times because deactivating the plugin will bring back mixed content errors.

Method 2: Setup SSL/HTTPS in WordPress Manually

This method requires you to troubleshoot issues manually and edit WordPress files. However this is a permanent and more performance optimized solution. This is what we’re using on WPBeginner.

If you find this method difficult, then you can hire a WordPress developer or use the first method instead.

As part of this method, you may need to edit WordPress theme and code files. If you haven’t done this before, then see our guide on how to copy and paste code snippets in WordPress.

First, you need to visit Settings » General page. From here you need to update your WordPress and site URL address fields by replacing http with https.

Update WordPress URLs

Don’t forget to click on the ‘Save changes’ button to store your settings.

Once the settings are saved, WordPress will log you out, and you will be asked to re-login.

Next, you need to set up WordPress redirects from HTTP to HTTPS by adding the following code to your .htaccess file.

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<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
</IfModule>

If you are on nginx servers (most users are not), then you would need to add the following code to redirect from HTTP to HTTPS in your configuration file:

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server {
listen 80;
server_name example.com www.example.com;
return 301 https://example.com$request_uri;
}

Don’t forget to replace example.com with your own domain name.

By following these steps, you will avoid the WordPress HTTPS not working error because WordPress will now load your entire website using https.

If you want to force SSL and HTTPS on your WordPress admin area or login pages, then you need to configure SSL in the wp-config.php file.

Simply add the following code above the “That’s all, stop editing!” line in your wp-config.php file:

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define('FORCE_SSL_ADMIN', true);

This line allows WordPress to force SSL / HTTPs in WordPress admin area. It also works on WordPress multisite networks.

Once you do this, your website is now fully setup to use SSL / HTTPS, but you will still encounter mixed content errors.

These errors are caused by sources (images, scripts, or stylesheets) that are still loading using the insecure HTTP protocol in the URLs. If that is the case, then you will not be able to see a secure padlock icon in your website’s address bar.

Not secure

Many modern browsers will automatically block unsafe scripts and resources. You may see a padlock icon but with a notification about it in your browser’s address bar.

Insecure content blocked

You can find out which content is served through insecure protocol by using the Inspect tool. The mixed content error will be displayed as a warning in the console with details for each mixed content item.

Mixed content errors displayed in browser console

You will notice that most URLs are images, iframes, and image galleries while some are scripts and stylesheets loaded by your WordPress plugins and themes.

Fixing Mixed Content in WordPress Database

Majority of the incorrect URLs will be images, files, embeds, and other data stored in your WordPress database. Let’s fix them first.

All what you need to do is find all mentions of your old website URL in the database that started with http and replace it with your new website URL that starts with https.

You can easily do this by installing and activating the Better Search Replace plugin. For more details, see our step by step guide on how to install a WordPress plugin.

Upon activation, you need to visit Tools » Better Search Replace page. Under the ‘Search’ field, you need to add your website URL with http. After that, add your website URL with https under the ‘Replace’ field.

Search and replace

Below that, you will see all your WordPress database tables. You need to select all of them to run a thorough check.

Lastly, you need to uncheck the box next to ‘Run as dry run?’ option, and then click on ‘Run Search/Replace’ button.

The plugin will now search your WordPress database for URLs starting with http and will replace them with secure https URLs. It may take a while depending on your WordPress database size.

Fixing Mixed Content Errors in WordPress Theme

Another common culprit causing mixed content error is your WordPress theme. Any decent WordPress theme following WordPress coding standards will not cause this issue.

First, you will need to use your browser’s Inspect tool to find the resources and where they are loading from.

Using inspect tool to find mixed content error

After that, you will need to find them in your WordPress theme and replace them with https. This will be a little difficult for most beginners, as you will not be able to see which theme files contain these URLs.

Fixing Mixed Content Errors Caused by Plugins

Some mixed content resources will be loaded by WordPress plugins. Any WordPress plugin following WordPress coding standards will not cause mixed content errors.

We don’t recommend editing WordPress plugin files. Instead, you need to reach out to the plugin author and let them know. If they do not respond or are unable to fix it, then you need to find a suitable alternate.

Note: If for some reason, you’re still encountering mixed content error, then we recommend using the Really Simple SSL plugin temporarily, so your users are not impacted while you fix the issue on a staging website or hire a developer.

Submit Your HTTPS Site to Google Search Console

Search engines like Google consider https and http as two different websites. This means you will need to let Google know that your website has moved to avoid any SEO issues.

To do that, you just need to go to your Google Search Console account and click on ‘Add a Property’ button.

Add https site as a new property in Google Search Console

This will bring up a popup where you need to add your website’s new https address.

Add your https URL

After that, Google will ask you to verify ownership of your website. There are several ways to do that, select any method and you will instructions to verify your site.

Verify your website

Once your site is verified, Google will start showing your search console reports here.

You also need to make sure that both the https and http versions are added in your Search Console.

This tells Google that you want the https version of your website to be treated as the primary version. Combined with the 301 redirects that you setup earlier, Google will transfer your search rankings to the https version of your website, and you will most likely see improvements in your search rankings.

We know that we did when switched our websites from http to https.

We hope this article helped you add HTTPS and SSL in WordPress.

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