There are a number of default settings in the /etc/ssh/sshd_config file that need to be enabled in order to harden the SSH server operation. Unsurprisingly, Linux security hardening is a specialized procedure in its own right, given the wide-range of subtly different Linux distributions. If possible, these should feature a minimum length of at least 10 characters, plus requirements for using special characters or upper and lowercase letters. The same password should never be used for multiple users or software systems. Don’t forget to configure expiration, as no password can provide adequate security indefinitely. When deploying services, go for a ‘default deny’ type of access.
When you have this setup, you can disable password based SSH login. Now, only the clients machines that have the specified SSH keys can access the server via SSH. This will kill all applications on the current virtual console, therefore defeating login spoofing attacks.
Finally, consider encrypting your full disk to avoid data loss in case of theft of machines or drives themselves. In general, a standard system update will make all the necessary changes. Curiously, because the configurations are loaded via the xmm registers, IDA actually misses the first two loaded arguments, which are the binary name and the pool IP placeholder. Donald A. Tevault – but you can call him Donnie – got involved with Linux way back in 2006, and has been working with it ever since.
It also defines what type of access is granted, such as read-only access or more. Although there are several combinations possible, it is not fine-grained. To define a more detailed kind of access, file ACLs can be used.
This functionality can be abused to load a malicious kernel and gain arbitrary code execution in kernel mode, so this sysctl disables it. In this short post, we covered many important configurations for Linux security. But, we’ve just scratched the surface of Linux Hardening—there are a lot of complex, nitty-gritty configurations.
The most secure Linux server or other computer is the one that is powered off and disconnected from the network. But if we want to actually use the machine to provide IT services, we need to maximize its security defenses when it is booted up and attached to the network or even the internet. The application rsync is a popular option for backing up data in Linux. It comes with a host of features that allow you to make daily backups or exclude certain files from being copied. It is notoriously versatile and, therefore, a great option for a vast array of Linux server security strategies.
When selecting a location, consider the potential for SSH key sprawl, in which individuals and organizations lack proper inventory. This is a huge problem because many maintain dozens or even hundreds of SSH key pairs per server. 14 Certificate Management Best Practices to keep your organization running, secure and fully-compliant. Join the Linux Security Expert training program, a practical and lab-based training ground. For those who want to become (or stay) a Linux security expert.
If you are looking to use the GNU Guix distribution, you should absolutely use the Nonguix channel or similar to get microcode updates. You will also gain access to the Canonical Livepatch Service, which provides livepatching for certain kernel variants. Note that the Hardware Enablement (HWE) kernel is not supported. If linux hardening and security lessons you are using Ubuntu LTS, consider subscribing to Ubuntu Pro. Canonical currently allows up to 5 machines with the free subscription. Note that, unlike Android, traditional desktop Linux distributions typically do not have full system Mandatory Access Control policies; only a few system daemons are actually confined.
These details are used by system to decide when a user must change his/her password. It also can be managed from ‘/etc/selinux/config‘ file, where you can enable or disable it. Configure the BIOS to disable booting from CD/DVD, External Devices, Floppy Drive in BIOS.
They are more common in server environments where individual services are built to operate independently. However, you may sometimes see them on desktop systems as well, especially for development purposes. My strategy to deal with this is to revoke all filesystem access first, then test if an application works without it. If it does, it means the app is already using portals and no further action is needed. If it doesn’t, then I start granting permission to specific directories. Many Linux distributions sends some telemetry data by default to count how many systems are using their software.