The Linux kernel’s network packet processing subsystem is called Netfilter, and iptables is the command used to configure it. Until recently, just plain iptables was the default firewall manager on every Linux distro. It still is on most distros, but Red Hat Enterprise Linux 7 and all of its offspring now use the new firewalld […]
Archives for September 2022
How to Verify the Syntax of the file /etc/ssh/sshd_config
If you have done any changes to the ssh configuration file, we will have to either reload or restart the sshd service. But if you have any syntax error in the file, the ssh service will not start and you might lose access to the server. To avoid these issues, there is an option in […]
mkfs.xfs: command not found
XFS is one of the fastest filesystems around, especially in combination with RAID volumes. But, this comes with a cost: you’ll need at least 1 GB of memory in your virtual machine if you want to use XFS. And if you want to be able to repair the filesystem, you’ll need at least 2 GB […]
lsof: command not found
At times, we face situations where we cannot unmount a disk as it says that the files are being used, but we cannot understand which file it is referring to. In such situations, we can check which files are open by which process is running on the system. This can be done using the lsof […]
raspistill: command not found
The Raspbian Linux distribution is convenient because aside from configuration conveniences, it also provides tools for working with the camera among other things. The command raspistill can be used to capture an image after a five-second preview period. $ raspistill -o test.jpg The raspistill utility has loads of options for manipulating the images it captures. […]
ansible-playbook: command not found
Using ad-hoc commands is an imperative method and is no better than using the SSH client to execute commands remotely. You need two components to make it into real, imperative orchestration: a playbook and modules. The playbook is the basis for your system’s deployment, configuration, and maintenance. It can orchestrate everything, even between hosts! A […]
How to Disable IPv6 on Ubuntu 22.04 LTS Jammy Jellyfish
Internet Protocol version 6 (IPv6) is a 128-bit number identifying an endpoint in a TCP/IP communication. This means that with IPv6 we can assign on the order of 1038 individual machines (devices). In contrast to IPv4, IPv6 uses a hexadecimal representation, eight groups of 16 bits each, separating the groups by a colon (:). Ubuntu […]
How to Disable IPv6 on Ubuntu 20.04 Focal Fossa
Internet Protocol version 6 (IPv6) is a 128-bit number identifying an endpoint in a TCP/IP communication. This means that with IPv6 we can assign on the order of 1038 individual machines (devices). In contrast to IPv4, IPv6 uses a hexadecimal representation, eight groups of 16 bits each, separating the groups by a colon (:). Ubuntu […]
aws-shell: command not found
aws-shell, released by AWS labs, is a rich command-line shell with built-in autocompletion and help documentation. It’s very similar to the previous interactive commands we learned about for Microsoft Azure and Google Cloud. It also offers robust auto-completion, including the ability to autocomplete resources such as EC2 instance names. For most commands, we simply prefix […]
sox: command not found
sox is the Swiss Army knife of audio manipulation, which is held in the package of the same name. Once installed, we can take a look at its man pages, where it is made clear that it can not only play an audio file, but it can also manipulate it! Here are the lines of […]