Messages in this thread | | | Date | 29 Nov 2002 08:55:00 +0200 | From | (Kai Henningsen) | Subject | Re: connectivity to bkbits.net? |
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miquels@cistron.nl (Miquel van Smoorenburg) wrote on 28.11.02 in <as6aks$amj$1@ncc1701.cistron.net>:
> 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/
Lesson #4 of firewalling: a friendly firewall will (unless there are *specific* reasons to do otherwise) allow for ICMP_UNREACH_NEEDFRAG (and some similar things), ping, and traceroute. That's how I usually set them up. (ping == good)
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