Quando eu mudo a política padrão de INPUT, a saída de iptables -L para após a terceira linha. Eu verifiquei tanto por ssh quanto localmente. Saída do meu terminal (sim, eu sei que não deveria estar usando root).
root@pi4:/# iptables -L -v
Chain INPUT (policy ACCEPT 73 packets, 16085 bytes)
pkts bytes target prot opt in out source destination
261 18964 ACCEPT tcp -- any any 192.168.0.0/16 anywhere tcp dpt:60022
94 7786 ACCEPT all -- lo any anywhere anywhere
0 0 ACCEPT tcp -- any any 192.168.0.0/16 anywhere tcp dpt:netbios-ssn
0 0 ACCEPT tcp -- any any 192.168.0.0/16 anywhere tcp dpt:microsoft-ds
0 0 ACCEPT udp -- any any 192.168.0.0/16 anywhere udp dpt:netbios-ns
4 962 ACCEPT udp -- any any 192.168.0.0/16 anywhere udp dpt:netbios-dgm
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
root@pi4:/# iptables -P INPUT DROP
root@pi4:/# iptables -L -v
Chain INPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
^C
root@pi4:/#