Включить/отключить межсетевой экран

ufw

Debian/Ubuntu

ufw disable
systemctl stop ufw
systemctl disable ufw

firewalld

CentOS 7

systemctl stop firewalld
systemctl disable firewalld

iptables

CentOS 7

yum install iptables iptables-services
systemctl enable iptables
systemctl start iptables

Arch Linux

pacman -S iptables
systemctl enable iptables
systemctl start iptables

Правила в файле

/etc/iptables/iptables.rules

nftables

Fedora

dnf install nftables
systemctl enable nftables
systemctl start nftables