Category Archives: CentOS

CentOS, CentOS 8, Linux, Parallels Desktop, Parallels Tools, RedHat

Installing Parallels Tools on Centos 8

N/B: Parallels have since fixed this in the latest version of Parallels Desktop 15, thus it’s no longer an issue

A little while back I tweeted Parallels via their @ParallelsCares twitter account to find out if they could provide support for Parallels Tools with CentOS 8.

RHEL 8 was released 7th May 2019, with Parallels 15 released 13th August 2019, so since CentOS is a free version of RHEL with the commercial, and copyright protected parts removed, I made the presumption that Parallels 15 would support it. However with CentOS 8 taking until 24th September 2019 to be released, all they did was respond to state that they didn’t support it, with a link to their KB article.

I went about looking for a fix, and it turns out it’s fairly easy. It needs two things:

  • Pretending to Parallels that what you’re installing is RHEL 8
  • The EPEL Repo enabled

Here’s the exactly what I did:

  1. Download the CentOS DVD image for the version that you want here
  2. In Parallels, Start the new VM Installation Assistant
  3. Select “Install Windows or another OS from a DVD or image file”
  4. Select “Choose Manually”, then “Select a file…”, and find the DVD image you’ve just downloaded
  5. It will claim “Unable to detect operating system”, click “Continue”
  6. When the Prompt comes up to select your operating system, select “More Linux” > “Red Hat Enterprise Linux”, then proceed through to creating and booting the VM
  7. Proceed with the install
    1. Ensure the network is enabled under “Network & Host Name”
    2. Ensure the drive is checked in “Installation Destination”
    3. To fix the error in “Installation Source”, select “On the network” > “http://”, and enter the following in the text box: mirror.centos.org/centos/8/BaseOS/x86_64/os
    4. Once it’s downloaded the metadata, under the “Software Selection” select the options you want for your install
    5. Proceed with the install, and make sure you enter a root password
  8. Once rebooted under a terminal, install EPEL using the instructions here. Ensure you run the command to enable the PowerTools repository too.
  9. Start the “Install Parallels Tools” process, ensuring that any existing mounted CD/DVD is unmounted. This is needed to mount the Parallels Tools DVD image.
  10. Run the following commands in a terminal:
    mkdir /media/cdrom
    mount /dev/cdrom /media/cdrom
    cd /media/cdrom
    ./install
  11. Proceed through the install process for Parallels Tools, and you should be done.

If you want to do this on an existing VM, shutdown the VM, go to Settings > General and change the type (above the VM Name), to Red Hat Enterprise Linux, then boot, and perform steps 9-11 above.

CentOS, Fail2Ban, Fedora, Fedora 19, FirewallD, Linux, RedHat

Firewalld, firewall-cmd and Fail2Ban

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Basically I’ve been looking at upgrading a web-server to the latest version of Fedora 19, or when it’s released later this year CentOS 7.0 (providing it’s easy for them when RHEL 7.0 is released), however knowing that iptables is now becoming redundant in favour of firewalld in Fedora I started looking at updating my web-server install script to work with firewalld.  Knowing part of that is Fail2Ban and that uses iptables my first port of call was finding a way of getting these two working together.

My first obvious search for “firewalld fail2ban” returned nothing helpful whatsoever, just people wanting a conf file to get it working with no actually helpful response, however once I found that firewalld uses firewall-cmd on the command line to control the rules I searched for that. This turned up a current bug posted on RedHat’s BugZilla: https://bugzilla.redhat.com/show_bug.cgi?id=979622 , where it turns out a very helpful soul, Edgar Hoch, has created an action.d conf file to get it all working: https://bugzilla.redhat.com/attachment.cgi?id=791126

CentOS, CentOS 6, Linux, Linux Kernel, RedHat, Shell Scripting

Installing the default Linux Kernel on a Linode CentOS 6 box

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While creating the new web-server for my employers, to replace a Fedora 10 box which gets no security updates, I needed to compile some software from source, meaning I needed the kernel sources.

Since I couldn’t easily obtain these I needed to install the Kernel provided by the distribution rather than the more recent kernel provided by Linode themselves.

The Linode Library provided a way of doing this for CentOS 5 but not for CentOS 6, thus I adapted the provided script for v5 into one that works with CentOS 6 et voila, distro provided kernel.

Here’s the full source available as a gist on github:

### Starting from a fresh CentOS 6 or newer Linode
### Enable the native kernel to boot from pvgrub
### It will autoconfigure itself with each yum update.
### This is adapted from a previous script for CentOS 5.5 found here:
### http://www.linode.com/docs/assets/542-centos5-native-kernel-selinux-enforcing.sh
### Provided via the linode wiki
### https://www.linode.com/docs/tools-reference/custom-kernels-distros/run-a-distributionsupplied-kernel-with-pvgrub#centos-5
### Provided without warranty, although since it should only be run
### on first box build if your box gets broken simply rebuild it

mkdir /boot/grub/

DISTRO_PLATFORM=`uname -p`
AWK_VERSION_MATCH="{if(\$1==\"kernel.$DISTRO_PLATFORM\") print \$2}"
KERNEL_VERSION=`yum -q list kernel | awk "$AWK_VERSION_MATCH"`

### Write template grub.conf
cat > /boot/grub/grub.conf << EOF
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE:  You have a /boot partition.  This means that
#          all kernel and initramfs paths are relative to /boot/, eg.
#          root (hd0)
#          kernel /boot/vmlinuz-version ro root=/dev/xvda
#          initrd /boot/initramfs-version.img
#boot=/dev/xvda
default=0
timeout=3
title CentOS ($KERNEL_VERSION.$DISTRO_PLATFORM)
        root (hd0)
        kernel /boot/vmlinuz-$KERNEL_VERSION.$DISTRO_PLATFORM root=/dev/xvda
        initrd /boot/initramfs-$KERNEL_VERSION.$DISTRO_PLATFORM.img
EOF

ln -s /boot/grub/grub.conf /boot/grub/menu.lst
yum -y install kernel
if [ $? -ne 0 ]; then
    echo "ERROR aborting..."
    exit 1
fi