Re: [Exim] OT. Problems on connecting to some servers on por…

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Autor: Tomer H.
Fecha:  
A: Fernando Sanchez
Cc: exim-users
Asunto: Re: [Exim] OT. Problems on connecting to some servers on port 25
Friday, April 30, 2004, 11:33:31 PM, Fernando Sanchez wrote:

FS> -----BEGIN PGP SIGNED MESSAGE-----
FS> Hash: SHA1


FS> I've noticed that some servers do not allow my server to connect on port
FS> 25 for SMTP, when doing a manual test with:


FS> $ telnet mx.some.server.com 25


FS> from the server it just stays on:


FS> Trying x.x.x.x


FS> but if I try to telnet that remote server from another box on mynetwork
FS> I get the welcome message from the MTA on the other side. Does anybody
FS> have had the same kind of problems? I try to search for my server on
FS> sever black lists but is not on any. I was trying with tcpdump, but
FS> don't know what to look for in the output. Any ideas?


I have had this issue with linux once, failing to connect
to one of ICQ's servers and to lists.netsys.com
(full-disclosure@??? mailing list).

The problem was with ECN, as their servers (ICQ & netsys)
did not support it, and caused their firewalls probably to
drop the packets.

Over the Linux kernel v2.4 tree you will find it at the Networking
category as: "IP: TCP Explicit Congestion Notification support", just
disable it.

HTH, Tomer.

----------------------------------
   Tomer H.    tomer@???
       IT Solutions Provider
www.metnix.com     info@???
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