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.
Need more details?
Consider the upgrade to Lynis Enterprise to receive additional details and guidance. The Enterprise version helps to you with daily health checks of your environment, learn in-depth system hardening, and resources to protect your systems better.See demo
Lynis is a technical security auditing tool for Unix flavors like Linux, macOS, AIX, Solaris, and *BSD. It is open source software and free to use. Typical usage include system hardening, compliance testing, and vulnerability scanning. The project has an active community, including development via GitHub.
Do you need to collect data from multiple systems or compliance reporting? Lynis Enterprise uses Lynis to collect the data and make your work easier.
Benefits: automate security audits, detailed reporting, compliance testing.
- Centralized management
- Improvement plan with priorities
- Predefined policies
- Integration (API)
- Improvement snippets for tools like Ansible, Chef, Cfengine, Puppet, and SaltStack