Open port in rhel7

 https://linuxconfig.org/how-to-open-http-port-80-on-redhat-7-linux-using-firewall-cmd

Open port 80 on RHEL

By default, the port 80 for http connection is filtered on Redhat 7 and 8 as you can only access this port from the actual localhost and not from any other public host. To open a port 80 on RHEL 7 and 8 Linux we need to add an iptables rule. For this RHEL uses firewall-cmd.

1. First add your port 80 rule with the following linux command:

   # firewall-cmd --zone=public --add-port=80/tcp --permanent
   

2. Once you add the above firewall rule, reload the firewall service with this command:

   # firewall-cmd --reload
   

3. And check whether the port was added to iptables rule:

   # iptables-save | grep 80
   -A IN_public_allow -p tcp -m tcp --dport 80 -m conntrack --ctstate NEW -j ACCEPT
   

4. If you decide to block/remove http port 80 firewall rule you can again use the firewall-cmd command:

   # iptables-save | grep 80
   -A IN_public_allow -p tcp -m tcp --dport 80 -m conntrack --ctstate NEW -j ACCEPT
   # firewall-cmd --zone=public --remove-port=80/tcp --permanent
   success
   # firewall-cmd --reload
   success
   # iptables-save | grep 80