network problems?

Peter Jeremy peterjeremy at
Thu Apr 19 22:38:08 UTC 2007

On 2007-Apr-19 11:43:05 +0300, Krassimir Slavchev <krassi at> wrote:
>The problem is when I try to access ftp servers, the connection stalls 
>randomly. Also I can't do cvsup and fetch.
>This happens only with machines running -current and when the traffic is 
>passed through router based on FreeBSD 4.4. One of the test machines is 
>my notebook which have installed 7.0-CURRENT (from today) and 5.4-STABLE 
>and I see this problem only with -current.

The default TCP send and receive spaces were increased just after
RELENG4 was branched.  The new receive space requires window scaling
to be used.  I know that some versions of IPfilter have bugs in their
window scaling code and incorrectly block packets as "out of window".

You could try reducing net.inet.tcp.recvspace or disabling
net.inet.tcp.rfc1323 and see if that helps.  (Though RELENG5 should
also be affected if this is the problem).

Are you in a position to run tcpdump on your router?  If so, can you
tcpdump both the internal and external interfaces and find packets
that don't make it thru?

Peter Jeremy
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