Category: Bash

The Bourne Again Shell (Bash) is a widely used Unix shell, ideal for both interactive use and shell scripting.

  • fail2ban and nftables – Useful Tips

    Troubleshooting Fail2Ban Issues with nftables

    Fail2Ban may sometimes cause issues. In many cases, it’s enough to delete the nftables rules created by Fail2Ban, briefly stop the service, and then restart it. On restart, Fail2Ban will automatically recreate all necessary nftables sets and rules.

    I’ll omit sudo in the following examples. It will be required when running nft commands.

    Example to delete the f2b-table in the inet family context:

    Bash
    nft delete table inet f2b-table
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  • nftables Cheat Sheet: Useful Commands for nft Part 2

    After explaining the basic nft concepts in Part 1, I’ll now present the most important commands in Part 2..

    I’ll omit sudo in the following examples. It will be required when running nft commands.

    Display the complete configuration:

    Bash
    nft list ruleset

    This command displays the entire current nftables ruleset.

    Since the ruleset can become quite large depending on its complexity, I’ve created a custom script that trims the output to the essentials: for multiline blocks within curly braces, only the first and last line are shown.

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  • nftables Cheat Sheet: Useful Commands for nft Part 1

    nftables is a modern packet filtering framework for Linux and is set to replace iptables in the long term. In this post, I present the most useful commands that have proven effective in my daily admin work.

    The creation of new tables and chains is rarely needed in my practice, so I won’t cover that here.

    In Part 1, I explain the basic concepts. In Part 2, I go over the most important commands.

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  • Full Linux System Backups with the dd_image.sh Script – Compressed, Remote, Automated

    Repository: https://github.com/andreas-schwab-swx/dd_image

    If you’re looking for a simple yet powerful solution for full disk image backups on Linux, the dd_image script offers a versatile tool: it creates complete disk images, compresses them on-the-fly, and transfers them automatically via SSHFS to a remote server – with logging, retention logic, and optional notifications.

    Features at a Glance

    • Full disk backups using dd
    • On-the-fly compression with xz
    • Remote storage via sshfs
    • Automatic cleanup of old backups
    • Progress monitoring and detailed logging
    • Prevents concurrent runs using a lock file
    • Optional email notifications on success or failure
    • Optional zero-fill for better compression
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  • grep Cheatsheet

    This overview summarizes the grep commands I frequently use to search for text in files.

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