New answers tagged backdoor
cat /etc/protocols (on Linux) will show you all possible protocols; though it is likely (?) your kernel won't support all of them. However the good news is that iptables, by default, acts on all protocols. So this line, which often comes at the end of your iptables.rules, -A FIREWALL-INPUT -j REJECT --reject-with icmp-host-prohibited rejects packets not ...
You said "I want to be 100% sure that my machine only connects where and when I want it to", but do you have a strategy for covering what is sent? Blocking ports is always a good idea, but to browse the web you'd want to be able to connect out on port 80, and at that point malware has a way to communicate out. You realise this, so you block all IP address ...
The following is only valid if an attacker is not able to control parts of your network, e.g. DNS servers or routers; if so, you are doomed anyway :) If I use a firewall that blocks all UDP and TCP packets but those that I explicitly allow to pass, can I be 100% sure that my machine does not connect anywhere without my approval? While you can be sure ...
Blocking all TCP and UDP traffic is the equivalent of pulling the network cable out of the back of your computer. Yes blocking TCP and UDP will stop unwanted connections from being made.... but its going to stop a lot of connections you do want.
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