hello,

I am using intel nics with netbsd-3-1 and netbsd-4-beta2 kernel 
versions. It seems that the hardware-assisted checksums don't work 
correctly.

example (disabled hardware-assisted checksums):
ifconfig wm0:

wm0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         capabilities=87<IP4CSUM,TCP4CSUM,UDP4CSUM,TSO4>
         enabled=0
         address: 00:14:22:1d:8b:41
         media: Ethernet autoselect (1000baseT full-duplex)
         status: active
         inet 139.18.25.35 netmask 0xfffffff8 broadcast 139.18.25.39
         inet6 fe80::214:22ff:fe1d:8b41%wm0 prefixlen 64 scopeid 0x1
         inet6 2001:638:902:1:214:22ff:fe1d:8b41 prefixlen 64 detached


bash-3.2# tcpdump -vpni wm0 port 22
tcpdump: listening on wm0, link-type EN10MB (Ethernet), capture size 96 bytes
14:58:28.922305 IP (tos 0x0, ttl 127, id 15365, offset 0, flags [DF], 
length: 40) 139.18.11.72.2430 > 139.18.25.35.22: . [tcp sum ok] ack 
2524156043 win 64243


example (enabled hardware-assisted checksums):
ifconfig wm0
wm0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         capabilities=87<IP4CSUM,TCP4CSUM,UDP4CSUM,TSO4>
         enabled=87<IP4CSUM,TCP4CSUM,UDP4CSUM,TSO4>
         address: 00:14:22:1d:8b:41
         media: Ethernet autoselect (1000baseT full-duplex)
         status: active
         inet 139.18.25.35 netmask 0xfffffff8 broadcast 139.18.25.39
         inet6 fe80::214:22ff:fe1d:8b41%wm0 prefixlen 64 scopeid 0x1
         inet6 2001:638:902:1:214:22ff:fe1d:8b41 prefixlen 64


bash-3.2# tcpdump -vpni wm0 port 22
tcpdump: listening on wm0, link-type EN10MB (Ethernet), capture size 96 bytes
15:11:16.469732 IP (tos 0x10, ttl  64, id 32065, offset 0, flags [DF], 
length: 292, bad cksum 0 (->741a)!) 139.18.25.35.22 > 139.18.25.33.65436: 
P 946513:946753(240) ack 1008 win 33580 <nop,nop,timestamp 22 22>

I think the problem only occurs with outgoing packets.

You can simply disable the hardware-assisted checksums, but it would be 
nice, if anyone could fix the problem.



Thank you for your efforts
Uwe