Locking users after X failed login attempts with pam_tally2

Using pam_tally2 on Linux Most Linux distributions use pluggable authentication modules (PAM). This modular type of configuration allows system administrators to configure and fine-tune the authentication of users. It also defines the behavior on specific events, like providing an invalid user account or password. PAM can use these events to automatically take an action, like locking an account. Introduction to PAM The configuration of PAM is not that hard, but there are risks involved in the process of making changes. […]

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Configure the minimum password length on Linux systems

Linux and password strength One of the options to improve password security is by setting a minimum length. This prevents users from choosing easy passwords. As part of Linux system hardening, you don’t want your passwords to be cracked too quickly by modern password crackers. Configuration Login settings The first area where you can set a password length is in /etc/login.defs. The related setting is PASS_MINLEN and already tells us it is about the minimum length of a password. Modern Linux […]

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File Integrity of Password Files

Authentication Security Password files on Linux are used to store user details, like your unique user ID and name. It defines who you are on the system, your access to files, and the permissions you have. Proper password management, together with file integrity of your password files, is important. It keeps your system and user accounts safe.   Password Files For most Linux distributions there are two related files available: /etc/passwd and /etc/shadow. The first file defines what local users […]

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Granting Temporary Access to Your Servers (Using Signed SSH Keys)

Temporary access with SSH In need of support from a colleague or vendor, but don’t want to give them permanent access? SSH has an option to allow temporary access! Next time you need to provide temporary access for an hour or day, use this great option. Our Setup We have two machines for this purpose. One is a system running Arch Linux, the client system. The other one is a server, running Ubuntu Linux. For temporary support, we have created a […]

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Distributing SSH keys: using ssh-copy-id, manually or automated

Distribution of SSH keys When you want to allow public key authentication, you have to first create a SSH keypair. Next step is then the distribution of the public key to the other systems. Let’s have a look at a few options, including using the ssh-copy-id utility. Option 1: Manually In the past, you had to log in manually to the new system and do things yourself. Especially if you created your key with a tool like PuTTYgen on Windows. […]

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