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Re: nft newbie



On Tue, Jul 12, 2022 at 08:00:42PM +0000, Marco wrote:
> Am Tue, 12 Jul 2022 21:17:40 +0200
> schrieb <tomas@tuxteam.de>:
> 
> > That looks like a sensible strategy to me.
> 
> It isn't at all, completely blocking incoming ICMP is a very stupid
> idea.

I didn't get that "blocking incoming ICMP" part. Just the "DROP instead
of REJECT" part. Blame it on missing incoming coffee.

If it was there, I agree with you: especially blocking the incoming
"fragmentation required" ICMP will cause you lots of grief [1] if you
are behind something with a smaller MTU (cf. path MTU discovery, the
next Wikipedia shop in your quarters carries that).

Cheers

[1] I've seen symptoms like: you ssh into a box, everything seems fine,
   until you do the first `ls -al'. Then the connection hangs. You start
   to believe in ghosts until you understand the underlying mechanism.
-- 
t

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