Linux关闭默认端口
25端口
apt-get autoremove sendmail-bin
53端口
systemctl stop systemd-resolved.service
systemctl disable systemd-resolved.service
rm /etc/resolv.conf
echo "nameserver 223.5.5.5" >> /etc/resolv.conf
111端口
systemctl stop rpcbind.socket
systemctl disable rpcbind.socket