Centos generally new Server have iptables enabled
for testing you can Flush ip tables :
iptables -xnvL (post output)
iptables -F
you can check as below :
ps -ef | grep ufw
ps -ef | grep firewall
you can disable if you running firewalld
systemctl status firewalld (check the status)
systemctl stop firewalld (stop the firewall) if you like to start again - systemctl start firewalld
If you using UFW firewal :
ufw status (if this running )
ufw allow icmp (can allow ICMP)
