How to let the Firewall of RHEL7 the SNMP connection passing?

How to let the Firewall of RHEL7 the SNMP connection passing? When I did this command on the computer: systemctl stop firewalld All the SNMP packet are passing well. When I restarted firewalld all the packet arre blocked. I tried several connfigruation with the firewall running of course, like: iptables -A INPUT -p tcp -m state --state NEW -m tcp --dport 161 -j ACCEPT or firewall-cmd --zone=public --add-port=161/tcp --permanent I've not get any error message but the SNMP still in TIMEOUT.