I’ve just ended configuring Nethserver as Gateway, DNS, DHCP, MultiWan etc… I’m literally in love with it, so simple that even one like me, without any special skills in linux is able to get astonishing results: thank you all.
Anyway, today I was inspecting the server’s logs and I’ve been afraid discovering that some internet IPs are brute forcing SSH and other services!
Frankly, I thought that out of the box there should have been some kind of firewall rules preventing any kind of traffic toward public IPs (red network).
So, I’ve tried to set up a simple rule:
Destination: Public IP
Sadly, it was not effective, I was able to ssh to the server from internet.
As a quick work around, I’ve changed sshd.conf.
Here comes the question: can I create a firewall rule to deny any kind of traffic (except OpenVPN) toward our public IPs? Could anyone please provide a quick explanation about how to do it?