Question 3How can the established keyword in an ACL entry be used?1 pointto permit only the returning TCP packets from an already existing TCP connection, and deny the initial TCP packet of a new session from an untrusted networkto permit both the initial TCP packet of a new session and the returning TCP packets from an existing TCP connectionto permit only the initial TCP packet of a new sessionto change a router into a true stateful firewall controlling the access on a session-by-session basis

The established keyword in an ACL entry can be used to permit only the returning TCP packets from an already existing TCP connection, and deny the initial TCP packet of a new session from an untrusted network. This helps in ensuring that only established connections are allowed and prevents unauthorized access from untrusted sources. By using the established keyword, you can permit both the initial TCP packet of a new session and the returning TCP packets from an existing TCP connection. This allows for the establishment of new connections while still maintaining the security of established connections. Alternatively, you can use the established keyword to permit only the initial TCP packet of a new session. This would restrict access to only new connections and deny returning packets from existing connections. Lastly, using the established keyword can also be used to change a router into a true stateful firewall controlling the access on a session-by-session basis. This means that the router can analyze and control the traffic based on the state of the connection, providing enhanced security and control over network access.