Matthias Oertli <[EMAIL PROTECTED]> writes:

> On the Debian 2.4.20 box the SYN, CWR and ECN flags are set to which the
> printserver replies with RST and ACK set (causing the connection to be
> terminated).
>
> CWR=Congestion window reduced, ECN=ECN-Echo - Whatever that means.
>
> This intrigues me. What's going on here, and how would I influence
> which flags are initially set? Is this even the problem?

,----[ /usr/src/linux/Documentation/filesystems/proc.txt  ]
| tcp_ecn
| -------
| This file controls the use of the ECN bit in the IPv4 headers, this is a
| new feature about Explicit Congestion Notification, but some routers and
| firewalls block trafic that has this bit set, so it could be necessary
| to echo 0 to /proc/sys/net/ipv4/tcp_ecn, if you want to talk to this
| sites. For more info you could read RFC2481.
`----

I also turn off tcp_timestamps as well, when its on it adds 18 bytes
(from memory) to the tcp header making MSS 1442 (instead of 1460).

I think CWR is part of ECN.
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