stackbees

Introduction Creating a new image is a step done outside of your OpenStack installation. You create the new image manually on your own system and then upload the image to your cloud. To create a new image, you will need the installation CD or DVD ISO file for the guest operating system. You will also need access to a virtualization tool. You can use KVM for this. Or, if you have a GUI desktop virtualization tool (such as, VMware Fusion or VirtualBox), you can use that instead. [Read More]

I want to force openstack to resize every instance on the same host if it is possible to do. How can I do that? Before that, why should I do that. Here, you have a use case, you are on a private cloud and running some critical virtual machines in a very limited resources. You should take a turn to do this. Add the following lines in /etc/nova/nova.conf allow_resize_to_same_host=True scheduler_default_filters=AllHostsFilter Restart Services [Read More]

Everybody knows top or htop. Ever wished there was something similar but to monitor your files instead of CPU usage and processes? Well, there is. Run this: watch -d -n 2 ‘df; ls -FlAt;’ and you’ll get to spy on which files are getting written on your system. Every time a file gets modified it will get highlighted for a second or so. The above command is useful when you grant someone SSH access to your box and wish to know exactly what they’re modifying. [Read More]

Use case login using the pem key Elevate your privileges Create a new user Set the password for the new user Restart SSH Service Use case The cloud images bundled by various linux distributions have password authentication disabled by default for security reasons. The only possible way to login to an instance launched using one of these images is by specifying a security key during boot and using the key to ssh. [Read More]

Install required softwares Get the Image Unarchive Concatenate all the VMDK files to single QCOW2 Upload to Glance Kali Linux is a Debian-derived Linux distribution designed for digital forensics and penetration testing. It is maintained and funded by Offensive Security Ltd. Mati Aharoni, Devon Kearns and Raphaël Hertzog are the core developers. Now a days lots of people using it for Security assessment. Here we will see how to create a QCOW2 image of Kali for Openstack. [Read More]

Some times, when you are doing a live migration , it will ended up with the following error in the nova-compute.log of hypervisor. The reason for this as follows. The Interface was removed by the user, but LIBVIRT doesnt acknowledged about this. But nova did. So, when nova initiates a live migration, libvirt is looking for this interface, which actually doesnt exists. virsh domiflist Interface Type Source Model MAC tap29b1bcde-c7 bridge qbr29b1bcde-c7 virtio fa:16:3e:79:06:2a tap887baa4b-2e bridge qbr887baa4b-2e virtio fa:16:3e:d8:e9:db At the same time [Read More]

What is an EXT4 The ext4 file system is a scalable extension of the ext3 file system. It can support files and file systems up to 16 terabytes in size. It also supports an unlimited number of sub-directories (the ext3 file system only supports up to 32,000), though once the link count exceeds 65,000 it resets to 1 and is no longer increased. Ext4 uses extents (as opposed to the traditional block mapping scheme used by ext2 and ext3), which improves performance when using large files and reduces metadata overhead for large files. [Read More]

Preface grep command syntax redirect output using pipe Regex patterns using -E Preface One of the most useful and versatile commands in a Linux terminal environment is the “grep” command. The name “grep” stands for “global regular expression print”. This means that grep can be used to see if the input it receives matches a specified pattern. This seemingly trivial program is extremely powerful when used correctly. Its ability to sort input based on complex rules makes it a popular link in many command chains. [Read More]

Meltdown is a chip-level security vulnerability that breaks the most fundamental isolation between user programs and the operating system. It allows a program to access the operating system kernel’s and other programs’ private memory areas, and possibly steal sensitive data, such as passwords, crypto-keys and other secrets. spectre-meltdown-checker is a simple shell script to check if your Linux system is vulnerable against the 3 “speculative execution” CVEs (Common Vulnerabilities and Exposures) that were made public early this year. [Read More]