[SNMP4J] UDP Checksum in trap packet in Sniffer

[Jochen Katz]

Hi,

> I have a snmp agent running and it can send traps. However, when I capture
> the trap packet in a sniffer(wireshark), I see "Incorrect Checksum(maybe
> caused by UDPChecksum Offload?)". Can anybody explain what could be causing
> this. I checked the fields of the packet and they seem to be fine.

most current network cards can compute the checksums in hardware, so the 
operating system / network driver do not compute it. Therefore the 
captured OUTGOING packets do not have the right checksum.

If you capture the packet on the receiving system, the packet will have 
the right checksum.

Regards,
   Jochen