Re: [2.1.91-pre1] tcp wierdness and lockup

Ricky Beam (root@defiant.interpath.net)
Sun, 29 Mar 1998 03:32:55 -0500 (EST)

Letting the chips fall where they may, I quote Alan Cox:
>> I have a friend that logs into my machine from a local ISP.
>> This ISP doesn't allow ping packets (perhaps any icmp, not sure?).
>
>In which case he will not be able to use the internet. He should change
>provider immediately to an internet provider instead.

Blocking ping's I can understand, but point-blank no ICMP?

>> logged in. However, after that, anything that requires a lot of output
>> (more than a few lines) locks his connection up hard.
>> (ls -la, xemacs, etc...)
>
>This is bcause they have blocked ICMP. You cannot block all ICMP. Fortunately
>this ISP will go out of business when Win98 comes out as it uses MTU
>discovery and lower MTU's on slower links.

I wish I could impress this point on our network technicians... ICMP is there
for _a_ _reason_. Turning it off will cause all kinds of problems. That's
exactly like turning off TCP.

--Ricky

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