TCP stack errors

Jose Hidalgo Herrera jose at
Mon Jan 31 08:30:10 PST 2005

I have a 4.10p5
	(cvsuped with RELENG_4_10 last friday)
that shows things like this with a netstat -sf inet:

                3630 discarded for bad checksums
                85 discarded for bad header offset fields
        1220093 bad connection attempts
         137097 embryonic connections dropped
        7 with bad checksum
the complete netstat can be found in:

One can assume that the server is that target for some stupid guy, 
BUT the thing is that IS the server the one SENDING the miscalculated 

I saw that with sshd connections, smtps, auths, etc.., the client sent
the handshake but the server was replying with wrong packages.

It occurs with different window-sizes, different flags, the network card
is an em:
	media: Ethernet autoselect (100baseTX <full-duplex>)
with two ip addresses in the same subnet (alias with /32 netmask)
no hardware failures reported.

It sends bad packages from both addresses.

Is there any bug I'm not aware of with this driver ?

Jose Hidalgo Herrera <jose at>
Corp. Hostarica

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