Re: linux kernel TCP, network connections and iptables

From: Alan Cox (
Date: Thu Sep 07 2000 - 16:51:50 EST

> should we just eat it and shut up (because that's the way TCP works and it
> will not change)?

It is part of the protocol requirement

> I haven't used iptables yet but I think they can handle packets with various
> bits sets (including RST), unlike ipfw. But, is there any way with iptables
> to know if a port is "used" or "unused" at any time? And if yes, at what
> state (listening, at the middle of a 3-way TCP handshaking etc) also?

Another very simple approach is to add the following to the top of the tcp
code that sends resets in the kernel

        static unsigned long last_time;

        if(jiffies-last_time < HZ/10)
        last_time = jiffies;

which will then limit to one RST per 10th sec

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