Re: connectivity to bkbits.net?

Miquel van Smoorenburg (miquels@cistron.nl)
Thu, 28 Nov 2002 23:59:24 +0000 (UTC)

In article <20021128211347.D27234@flint.arm.linux.org.uk>,
Russell King <rmk@arm.linux.org.uk> wrote:
>On Thu, Nov 28, 2002 at 06:53:00PM +0200, Kai Henningsen wrote:
>> >From two or three traceroutes, that problem seems to be at the SGI end. I
>> can't get to them either (nothing after the same IP as for you, at hop
>> #17, some place at Genuity), but you are practically next door.
>
>Lesson #1 of firewalling: drop everything.
>Lesson #2 of firewalling: only accept what you absolutely have to.

Lesson#3 of firewalling: due to #1 and #2 most admins block
ICMP_UNREACH_NEEDFRAG as well (ICMP == ping == bad) breaking
path MTUd. http://alive.znep.com/~marcs/mtu/

Note that IPv6 has no fragmentation and pMTUd is mandatory.
Oh joy.

Mike.

-- 
They all laughed when I said I wanted to build a joke-telling machine.
Well, I showed them! Nobody's laughing *now*! -- acesteves@clix.pt


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