From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030703 Description of problem: This is from tcpdump, when a native (64-bit) application attempts to subscribe to a multicast group: 14:22:19.150000 10.0.30.20 > 224.0.0.22: igmp v3 report, 1 group record(s) [gaddr 239.255.0.11 to_in { }] bad igmp cksum ebff! (DF) [tos 0xc0] [ttl 1] (id 0, len 40, optlen=4 RA) I haven't tried a 32-bit application, so I don't know if it would work or not. I strongly suspect it wouldn't. The packet is obviously ignored by the receiving router(s), so the application ends up not receiving any traffic. Version-Release number of selected component (if applicable): kernel-2.4.21-15.ELsmp and 2.4.21-9.0.3.ELsmp How reproducible: Always Steps to Reproduce: 1. run tcpdump -vvv -n igmp 2. run any multicast listener (routed/gated would do, but it's not provided, zebra will probably do as well) 3. Actual Results: observe the bad igmp cksum message from tcpdump Additional info:
Also look at: http://lists.suse.com/archive/suse-amd64/2004-Feb/0322.html for another instance of the same bug, and a proposed solution. I tested that solution (attached below) and it seems to work for me.
Created attachment 100311 [details] IP partial-checksum fix for x86_64
*** This bug has been marked as a duplicate of 131048 ***
A fix for this problem was committed to the RHEL3 U4 patch pool on 14-Sep-2004 (in kernel version 2.4.21-20.6.EL).
An errata has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2004-550.html