Centos#
firewall-cmd --zone=public --add-port={PORT}/tcp --permanent
--zone # Scope
--add-port=80/tcp # Add port, format: port/protocol
--permanent # Make the operation permanent, without this parameter, it will be invalid after restart
# For example, to allow port 80 for HTTP protocol, you can use the following commands:
sudo firewall-cmd --add-port=80/tcp --permanent
sudo firewall-cmd --reload
Ubuntu#
Ubuntu uses ufw firewall by default. To allow a port, you can use the following command:
sudo ufw allow <port>/<protocol>
# For example, to allow port 80 for HTTP protocol, you can use the following command:
sudo ufw allow 80/tcp
Debian#
Debian uses iptables firewall by default. If it is not pre-installed on the system, you can execute the following commands to install iptables:
apt-get update
apt-get install iptables
apt-get install iptables-persistent
To allow a port, you can use the following command:
sudo iptables -A INPUT -p <protocol> --dport <port> -j ACCEPT
# For example, to allow port 80 for HTTP protocol, you can use the following command:
sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT
# Save rules (invalid after restart)
iptables-save
# Save rules (still effective after restart)
netfilter-persistent save
netfilter-persistent reload
# View current firewall rules
iptables -L