Based on this question: "Safe mode" on Linux? - So there is a configured knockd on a server, and a wrong firewall command was given out, so everybody got locked out from the server via layer3 (iptables). OK.
Could this be resolved by knocking the ports as in the knockd, so then the knockd will open given ports? Could this be a last chance to get in to the server via layer3?
As comment of the article Knockd, to secure your ports, i’ve received:
“Port knocking is bad idea; a very bad idea.
...”
Well, in my opinion knockd it’s a layer of security, perhaps thin but still can save you from some brute force script and so it adds a bit of security to your solution, in this article i’ll show you fail2ban that add another layer of security to our network services.
If I try to start it via boot, it fails.
Iptables, is a great tool to create firewall in Linux, actually it is not only for that, but useful to pre-process or post-process any package of data that arrives to our Linux Operating System machine.
The other day I was needing to block the access to my network using the mac address of a machine, and Iptables come to save my day.
Fail2Ban is an intrusion prevention framework written in the Python programming language. It is able to run on POSIX systems that have an interface to a packet-control system or firewall installed locally (for example, iptables or TCP Wrapper).
The story starts when I read the news about Linux Trojan.
I tried to block the IP of that trojan but one led to another and now I'm confused about Fedora firewall.
However I wonder if anyone can help to figure out what's the difference between firewall and firewalld?
Should I download firewalld on my system?
Which one is better original firewall comes with fedora 17 or firewalld?
I have an OpenWrt router where I installed knockd:
knockd.conf
[options]
logfile = /var/log/knockd.log
[openSSH]
sequence = 7000,8000,9000
seq_timeout = 5
command = /usr/sbin/iptables -I INPUT -s %IP% -p tcp --dport 22 -j ACCEPT
tcpflags = syn
[closeSSH]
sequence = 9000,8000,7000
seq_timeout = 5
command = /usr/sbin/iptables -D INPUT -s %IP% -p
I need a firewall because I was decade long user of internet security suites on windows.
How to Ensure Data Security by Using an Effective Firewall
By V K Rajagopalan
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