Lynis Security Controls
SSH-7408 - SSH configuration
Proper hardening of your SSH configuration can reduce known weaknesses
How to solve
The secure shell, or SSH, is one of the most used services. Nearly all machines have a SSH daemon running, to allow system administrators connect and manage the system. SSH is not limited to interactive system administration via the shell. Things like backups, remote configuration, and data transfers are common other uses as well.
Since SSH has an important function on the system, and firewalls are often opened up to allow traffic, proper hardening of the service is needed. Lynis checks for several key options and helps to avoid weak configurations. With every system having a different role, the right combination of settings needs to be configured.
Harden your SSH configuration with the specified configuration option listed in the Lynis output. Consult the SSH documentation for the meaning of each option, and select the best possible option for your system. Where possible choose the most strict option, to increase your security defenses.
The specific configuration settings to harden are listed in the log file (/var/log/lynis.log) and your report file (/var/log/lynis-report.dat).
A note from the SSH man page: Note that disabling TCP forwarding does not improve security unless users are also denied shell access, as they can always install their own forwarders.
- OpenSSH Settings (Man page of OpenSSH with settings)
- Audit and harden your SSH configuration (Tips to improve the security of OpenSSH)
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Linux and Unix System Hardening
This information is provided as part of the Lynis community project. It is related to Lynis control SSH-7408. All information should be considered as-is, without guarantees. Any advice or snippets should be tested before implementing in production environments.
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