There are a number of ways that the Uyuni Server can communicate with clients. Which one you use depends on your network architecture.
The Uyuni daemon (
rhnsd) runs on traditional client systems and periodically connects with Uyuni to check for new updates and notifications.
It does not apply to Salt clients.
Push via SSH and Push via Salt SSH are used in environments where clients cannot reach the Uyuni Server directly. In this environment, clients are located in a firewall-protected zone called a DMZ. No system within the DMZ is authorized to open a connection to the internal network, including the Uyuni Server.
OSAD is an alternative contact method between Uyuni and its clients. OSAD allows registered client systems to execute scheduled actions immediately.