Liberando ping para máquina de firewall e para a rede

iptables -A INPUT -p icmp --icmp-type 0 -m limit --limit 1/sec -j ACCEPT

iptables -A FORWARD -p icmp --icmp-type 8 -m limit --limit 1/sec -j ACCEPT

iptables -A FORWARD -p icmp --icmp-type 0 -m limit --limit 1/sec -j ACCEPT

iptables -A OUTPUT -p icmp --icmp-type 8 -m limit --limit 1/sec -j ACCEPT