# Manually installing SSM Agent on Red Hat Enterprise Linux instances
<a name="agent-install-rhel"></a>

The Amazon Machine Images (AMIs) for Red Hat Enterprise Linux (RHEL) that are provided by Amazon do not come with Amazon Systems Manager Agent (SSM Agent) preinstalled by default. For a list of Amazon managed AMIs on which the agent might be preinstalled, see [Find AMIs with the SSM Agent preinstalled](ami-preinstalled-agent.md).

Use the information in this section to help you manually install or reinstall SSM Agent on a RHEL instance.

**Before you begin**  
Before you install SSM Agent on a RHEL instance, note the following:
+ For important information that applies to installation of SSM Agent on all Linux-based operating systems, see [Manually installing and uninstalling SSM Agent on EC2 instances for Linux](manually-install-ssm-agent-linux.md).
+ If you use a `yum` command to update SSM Agent on a managed node after the agent has been installed or updated using the SSM document `AWS-UpdateSSMAgent`, you might see the following message: `"Warning: RPMDB altered outside of yum."` This message is expected and can be safely ignored.

**Topics**
+ [Install SSM Agent on RHEL 8.x, 9.x, and 10.x](agent-install-rhel-8-9.md)
+ [Install SSM Agent on RHEL 7.x](agent-install-rhel-7.md)