Re: 2.4.0 tcp over firewall - no connection

Eugene Crosser (
11 Jan 2001 00:38:36 +0300

In article <>,
Doug McNaught <> writes:

>> I noticed rather strange behavior: stock 2.4.0 with old ISA 3Com
>> on UP compiled as UP cannot open TCP connection to hosts behind a
>> firewall. E.g. it is impossible to go to -
>> connect just never finishes. 2.2.17 on the same hardware works
>> right. 2.4.0 on SMP over PPP connection works right too. MTU
>> is 1500 in both cases. In both cases, kernel is compiled with
>> netfilter as modules, but those are not loaded.
> Known problem, exhaustively discussed on the list, and not related
> to your NIC. Disable ECN (explicit congestion notification), either
> in your kernel compile or in /proc/sys/<something>.

This really was ECN, sorry for noise in this list...

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