How to restrict access of one network to another?

Question

Cisco

There are 4 networks, one server and one admin PC. It is necessary that everyone has access to the server, and networks cannot exchange traffic. Admin must have access to all. How to do it?

Answer 1

Set up a firewall on the router.

Answer 2

do not specify the default gateway and explicitly register routes for each network to the server and to the admin, and it is enough for the admin to register the router as the default gateway or all networks and the server explicitly.

Answer 3

well, there is no firewall in Cisco Packet Tracer:
access-list 100 deny ip any 192.168.0.0 0.0.3.255
access-list 100 permit ip any any
access-list 104 permit tcp 192.168.0.0 0.0.3.255 host 192.168.4.2 eq ftp
access- list 104 permit ip host 192.168.10.4 host 192.168.4.2
per VLAN (192.168.0.1 to 192.168.3.0)
ip access-group 100 in
and out to FTP
ip access-group 104 out