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27

This is close to ask whether a shutdown computer needs updates. The answer is not if and only if you are sure that it will always stay off. Your question should receive a similar answer: if you are sure that no listening services are active and will never be you do not need to block incoming connections. But in real world, no network service at all is hard ...


10

Does a machine with no listening services strictly need a firewall? Not really. Does a machine with no listening services exist in practice? Not really, if we're talking about the more common desktop & server operating systems. If you somehow identify and disable every single service that listens on a TCP or UDP port, an update to a package could ...


6

It depends on the risk profile and the stakes involved (these in turn depend on what the machine is used for). Just a few reasons why you MAY need a firewall: A lurking vulnerability in the machine's network stack may enable an attack even if no open TCP or UDP ports exist. The famous "ping of death" attack comes to mind. There may be a ...


4

In short, no. Using firewalls for this is really a bad practice (a form of treating the network layer as access control, a big Considered Harmful), which inevitably leads to bad things like insecure services being left open to LAN or to localhost, in ways that can be exploited. But if you use an operating system with tons of default services that are hard or ...


4

The approach is wrong. The whole point of DNS is that the domain name is what identifies the site or service, and the underlying IP addresses are abstracted away and subject to change. A service is not guaranteed to be uniquely associated with one IP address, nor is an IP address guaranteed to be uniquely associated with one service. Even if you do manage to ...


3

I'll be using the terms ONT (Optical Network Terminal) to refer to your CPE (Customer-premises equipment) ONU, and OLT (Optical Line Terminal) to refer to the network provider's termination point, where the path forward to your ISP begins. To directly address your questions: Simple frame discard. Think of it like a hub network where a device only cares ...


2

Although you probably don't really need a firewall if there no listening service, it can be hard to be sure that there aren't any. Suppose the user of the machine clicks on a trojan horse that installs a listening service, now your premise no longer applies. Firewalls can also be useful for restricting outgoing connections by policy. For instance, if malware ...


2

The trust of HTTPS in normal (ie consumer) use cases, such as network banking, is tied to root certificates preinstalled in your browser. The certificate presented by the web server is validated against one of these root certificates. So if a hostile admin on the network was to create a fake page with a fake certificate, it would be rejected by your browser....


1

Why for every pair is required a keystone and a nic? Why is not possible to use all the needed pairs on the same keystone and nic? Keystones are just passive connectors. You don't need them, just create the required connections any way you like: What you need for 10BASE-T and 100BASE-TX is to split transmit/receive directions and connect each to a separate ...


1

No perfectly configured, bug-free server needs a firewall, listening services or not. After all, what does the FW actually do? It blocks connections to ports where anyway we aren't listening, and lets them through on the ports we are listening. So it actually doesn't change a thing. So we don't use firewalls to block off unused ports. We use firewalls as an ...


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