Why am I able to connect to Wi-Fi(router) without any issues while all the In/Out traffic is blocked with UFW

askingUbuntuAboutKubuntu

10/11/23, 7:16 PM

When I block all the traffic with ufw, e.g.:

ufw default deny incoming
ufw default deny forward
ufw default deny outgoing

I can't receive or send anything, but I still able to connect to my home Wi-Fi network.

Is this intended? Can you please explain why?

1 + 4

firewall

wireless

ufw

askingUbuntuAboutKubuntu

10/11/23, 7:32 PM

I think I found the reason, yet would love to get a comprehensive answer(if anyone would care to). This is probably due to predefined rules within the `before.rules`. Going to investigate in depth this one

matigo

10/11/23, 11:17 PM

This is an apple and oranges thing. You don’t have network traffic until you are connected to a network. An outgoing device handshake, regardless of how it is carried out, is not technically network traffic. This is why airplane mode will remove power from the transmitters when enabled rather than simply employing firewall rules.

askingUbuntuAboutKubuntu

10/12/23, 6:07 AM

@matigo Airplane mode is a different thing with a different goal, it doesn't care about what happens within the network of a device. Same principle with kill switches. Firewalls (soft & hardware) do care. Device handshake happens on another layer - the network - and not by magic. It's an inner network, yet a network regardless. The fact is, the handshake does goes through iptables(how else) to establish a connection and rules for this are just pre-defined with a disto. Same goes for ICMP, for example. Prove me wrong please.

matigo

10/12/23, 6:55 AM

Not my job to prove anything. I provided an answer you disagree with. I will not walk through lines of code and logic as though this were a pair programming exercise. Such is life.

Score:0

Ubuntu

Pilot6

10/13/23, 2:02 PM

UFW rules are not apply until the interface is up.

It happens after a handshake. But you shouldn't be able to get an IP address if UDP is blocked.

+ 0

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EN: Why am I able to connect to Wi-Fi(router) without any issues while all the In/Out traffic is blocked with UFW

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