Monitor and Administrate 4 SAP Systems

If there are 4 systems installed SAP, how should I connect all of them in one network so that I can administrate the 4 systems with one among them as main server.

This should help you:

After installing an R/3 System, you can use transaction RZ20 to monitor the system. To monitor all systems of your system landscape centrally from one system, first customize the alert monitor by choosing Tools > CCMS > Configuration > Alert monitor or calling transaction RZ21.

Then, to specify the remote systems by System ID and RFC destination (which must have been created beforehand), choose Technical infrastructure > Create remote monitoring entry.

Next, to change your monitor definitions (you can only change your own monitors), choose Tools > CCMS > Control/Monitoring > Alert monitor or call transaction RZ20.

Activate the maintenance function by choosing Extras > Activate maintenance function.
Then, double click on the monitor and choose Monitoring change.
Parameter R3system defines which systems can be monitored by an alert monitor. Change parameter R3system from (only the current R/3 System can be monitored) to (all R/3 Systems defined in RZ21 can be monitored). Save the changes.

It will help you monitor & use spome other activities centrally.