Category Archives: Linux Administration

Permanently reject a specific email sender address using postfix

Postfix generally accepts all sender addresses. It might be needed in some rare cases to reject one sender addresses for some reason. With postfix, there is the possibility to use the “check_sender_access” to set individual actions per sender address. For the … Continue reading

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How to get scrollbar arrows in Linux Mint 17

Linux Mint is missing the scrollbar arrow buttons at the end of the scrollbars. There are situations in which those buttons can be very useful. This how-to will explain how to get them back. Sadly I could not find any … Continue reading

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Verifying SSH configuration with a scan

Managing a number of Linux servers and keeping them secure can be a challenge. Certain tools can make the life of an admin a lot easier. To ensure an ssh daemon complies with a desired security configuration the admin can use a scanner … Continue reading

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Debug SSH Connection issue in key exchange

Securing a server means hardening the SSH server settings, but doing so can also cause issues with ssh clients. Finding the cipher or algorithm causing a failled connection can be tricky. Depending on the client used, the error message might be very … Continue reading

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Automount a luks encrypted volume on system start

Linux supports encrypted volumes with luks. When a luks encrypted volume is set up during installation to be booted from, the volume is already configured and set up. When an encrypted volume is set up afterwards, the volume remains locked until … Continue reading

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Harden SSH server settings

Many Linux Administrators use ssh on a daily basis. Many of the ssh servers are in their default configuration. Not changing the default configuration puts the security of the server at risk. That is why it is important to follow a few … Continue reading

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Get vim to paste content without modification

When content is pasted into vim, it tries to automatically detect and re-indent the content. This works most of the time but sometimes it does not, and that can be annoying, but vim would not be so popular if there wasn’t … Continue reading

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Change Date and Time format for LinuxMint panel applet

Modern Linux distributions like LinuxMint provide a nice GUI which is highly configurable. There are so many options and possibilities that most users new to it cannot find where things are configured. Finding the right options means taking some time to … Continue reading

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Manage SSH-keys with the SSH-agent

Many webservices generate ssh keys to access their service. With the amount of services the number of SSH keys grows. To avoid dealing with the keys in the command line and the ssh_config(5), you can simply add the ssh-key to the … Continue reading

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Create a luks encrypted partition on Linux Mint

Encryption is not only for someone who has something to hide. There are simple concerns like a lost or stolen laptop that justify a full disk encryption. There are only a few steps necessary to create a encrypted partition. In … Continue reading

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