A customer’s MSR router is connected to the Internet through the WAN interface S1/0, and to the office network through the LAN interface GE0/0. At present, office network users can access the Internet normally.
Add the following ACL configuration on the router:
firewall enable
firewall default deny
# acl number 3003
rule 0 deny icmp
rule 5 permit tcp destination-port eq 20
#
interface GigabitEthernet0/0
firewall packet-filter 3000 inbound
firewall packet-filter 3000 outbound
So ______ .

A network connection is as follows:
HostA----GE0/0--MSR-1--S1/0---------S1/0--MSR-2--GE0/0----HostB
The customer requires that only ICMP messages between HostA and HostB are restricted. Which of the following is feasible? (multiple choice)

Ping is actually an application developed based on the ______ protocol.

In the process of establishing a PPP session, when authentication is set but the authentication fails, the PPP link enters the ______ phase.

The following description of the characteristics of the router is correct ______. (Multiple choice)