Re: [PATCH v2] add stealth mode

From: David Miller
Date: Mon Jul 06 2015 - 22:22:56 EST


From: Matteo Croce <matteo@xxxxxxxxxxx>
Date: Mon, 6 Jul 2015 21:44:06 +0200

> 2015-07-06 12:49 GMT+02:00 <Valdis.Kletnieks@xxxxxx>:
>> On Thu, 02 Jul 2015 10:56:01 +0200, Matteo Croce said:
>>> Add option to disable any reply not related to a listening socket,
>>> like RST/ACK for TCP and ICMP Port-Unreachable for UDP.
>>> Also disables ICMP replies to echo request and timestamp.
>>> The stealth mode can be enabled selectively for a single interface.
>>
>> A few notes.....
>>
>> 1) Do you have an actual use case where an iptables '-j DROP' isn't usable?
>
> If you mean using a default DROP policy and allowing only the traffic
> do you want,
> then the use case is where the port can change at runtime and you may not want
> to update the firewall every time

Dynamically updated firewalls are "a thing" and quite effective for
solving problems like this one.

With nftables such updates are even extremely efficient.
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