Close ports on Linode Debian

WLS-ITGuy

Hello all,

I have been trying to figure out what firewall I have on our Debian host but cannot. I did a port scan and found that we have some ports open that I want to close as I know we don't use any of them.

JaredBusch

Use UFW

apt-get install -y ufw

Then open only what you need to use. Here are examples.

ufw enable
ufw allow in ssh
ufw allow in http
ufw allow in https
ufw allow in 10000:20000/udp

JaredBusch

FYI, this writes to iptables for you as far as I know.

scottalanmiller

Beyond using a firewall, you can also set whatever ports to simply not be open. Firewalls block ports, but leave them open. You can close them additionally. Your best defense is doing both.

1337

By default Debian comes with iptables. It will allowing everything but a normal Debian install have no services running.

Run iptables -L to see the firewall rules.

On Debian 10 the default is nftables.