[Tickets #4814] Re: vlad.horde.org timeout after EHLO

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Ticket URL: http://bugs.horde.org/ticket/?id=4814
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 Ticket             | 4814
 Updated By         | cbs at cts.ucla.edu
 Summary            | vlad.horde.org timeout after EHLO
 Queue              | Horde.org Servers
 Type               | Bug
 State              | Accepted
 Priority           | 2. Medium
 Owners             | 
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cbs at cts.ucla.edu (2007-01-18 15:22) wrote:

I'm looking at  http://lwn.net/Articles/92727/

The window scaling in linux changed in 2.6.17.  If I disable scaling on my
inbound MX, messages come through.  With scaling enabled, I get nothing.

Unfortunately (for me), I can't leave scaling disabled on my inbound MX.

Thinking about it more, disabling scaling on vlad/coyote may not do
anything. If the horde machines are behind a firewall/router that's
stripping tcp scaling from the headers one-way, then any scaling that my
MX tries to do will be stripped, leaving me with a large size window and
vlad/coyote with a very small window, and few or no packets transferred
past a certain point.

This would suggest that anybody running a linux 2.6.17+ kernel on their MX
host with tcp window scaling enabled (the default) and the default values
for tcp_wmem and tcp_rmem should be having the same problems receiving
mail from the horde mailing lists.