Description of problem: When Ethereal captures outgoing UDP packets it reports a wrong checksum on them however when I use it to capture the packets on the receiving side the checksum is OK. Version-Release number of selected component (if applicable): 0.10.5 from current devel How reproducible: Run a program which sends out UDP packets and capture them using Ethereal. Steps to Reproduce: 1. 2. 3. Actual results: The captured packets have incorrect checksum but in fact they haven't as verified on receiving side. Expected results: The captured packets have correct checksum. Additional info: tcpdump seems to capture the packets with right checksum.
Sorry for the last info: tcpdump actually captures the packets with WRONG checksums too. So the problem lies probably in libpcap?
Created attachment 105578 [details] A very simple program to send UDP packets Change IP address to host you want to send the packets to.
which NIC?
02:0c.0 Ethernet controller: Intel Corp. 82540EM Gigabit Ethernet Controller (rev 02) Subsystem: Dell Computer Corporation: Unknown device 0151 Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 9 Memory at fcfe0000 (32-bit, non-prefetchable) I/O ports at df40 [size=64] Capabilities: [dc] Power Management version 2 Capabilities: [e4] PCI-X non-bridge device. Capabilities: [f0] Message Signalled Interrupts: 64bit+ Queue=0/0 Enable- libpcap version 0.8.3, kernel 2.6.8-1.610
some network cards compute the checksum on their own.. maybe a dup of bug #129823
Oh, same NIC... *** This bug has been marked as a duplicate of 129823 ***
This is described by ethereal developers - http://www.ethereal.com/faq#q5.14
Changed to 'CLOSED' state since 'RESOLVED' has been deprecated.