firewalldに慣れないので、UFWをRedhat系で扱う場合。
2018/01/12 CentOS6用に作成
2023/11/27 AlmaLinux9用に更新

sudo yum -y update
sudo yum -y upgrade
sudo yum -y install vim wget make gcc-c++ perl

# https://launchpad.net/ufw/
ufw_ver=0.36
ufw_ms_ver=.2
ufw_url=https://launchpad.net/ufw/${ufw_ver}/${ufw_ver}${ufw_ms_ver}/+download/ufw-${ufw_ver}${ufw_ms_ver}.tar.gz


mkdir -p ${HOME}/src
cd ${HOME}/src
wget $ufw_url

tar xzf ufw-${ufw_ver}${ufw_ms_ver}.tar.gz
cd ufw-${ufw_ver}${ufw_ms_ver}
sudo python ./setup.py install
cd ../
rm -rf ufw-${ufw_ver}${ufw_ms_ver}
sudo chmod -R g-w /etc/ufw /lib/ufw /etc/default/ufw /usr/local/sbin/ufw

sudo systemctl stop firewalld
sudo systemctl disable firewalld

# ここからはrootユーザで
sudo su -
ufw disable
yes y | ufw reset
ufw default deny incoming
ufw default allow outgoing
ufw allow from 192.168.0.0/24 to any port 22
yes y | ufw enable
ufw status
# 検索タグ CentOS6 UFW iptables firewall AlmaLinux9