Configure firewalld on AlmaLinux 9

Status

systemctl status firewalld
firewall-cmd --state
firewall-cmd --list-all

Allow common services

firewall-cmd --permanent --add-service=http
firewall-cmd --permanent --add-service=https
firewall-cmd --permanent --add-service=ssh
firewall-cmd --permanent...

Configure firewalld on RHEL 9

Status

systemctl status firewalld
firewall-cmd --state
firewall-cmd --list-all

Allow common services

firewall-cmd --permanent --add-service=http
firewall-cmd --permanent --add-service=https
firewall-cmd --permanent --add-service=ssh
firewall-cmd --permanent --ad...

Configure UFW on Ubuntu 24.04

Install and set defaults

apt install -y ufw
ufw default deny incoming
ufw default allow outgoing

Allow services

ufw allow ssh
ufw allow 80/tcp
ufw allow 443/tcp
ufw enable

Status

ufw status verbose

Allow from specific IP

ufw allow from 192.168.1.100 to a...

Configure UFW on Debian 12

Install and set defaults

apt install -y ufw
ufw default deny incoming
ufw default allow outgoing

Allow services

ufw allow ssh
ufw allow 80/tcp
ufw allow 443/tcp
ufw enable

Status

ufw status verbose

Allow from specific IP

ufw allow from 192.168.1.100 to any...

Configure iptables on Gentoo Linux

Install

emerge --ask net-firewall/iptables

Ruleset (/etc/iptables/iptables.rules)

*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp --d...

Configure UFW on Arch Linux

Install and set defaults

pacman -S --noconfirm ufw
ufw default deny incoming
ufw default allow outgoing

Allow services

ufw allow ssh
ufw allow 80/tcp
ufw allow 443/tcp
ufw enable

Status

ufw status verbose

Allow from specific IP

ufw allow from 192.168.1.100...

Configure PF Firewall on OpenBSD 7.5

/etc/pf.conf

ext_if = "em0"
set block-policy return
set loginterface egress
set skip on lo0
block log all
pass in quick on egress proto tcp to port ssh \
    flags S/SA keep state (max-src-conn 15, max-src-conn-rate 5/3, overload  flush global)
pa...

Configure NPF Firewall on NetBSD 10

/etc/rc.conf

npf=YES
npf_conf=/etc/npf.conf

/etc/npf.conf

$ext_if = inet4 addr "wm0"
alg "icmp"
group default {
    pass stateful on lo0 all
    pass stateful all
    pass stateful in final on wm0 proto tcp to $ext_if port 22
    pass stateful in final on...