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authorJonas Danielsson <jonasdn@axis.com>2016-06-23 18:26:32 +0200
committerDenys Vlasenko <vda.linux@googlemail.com>2016-06-23 18:26:32 +0200
commit4d5acd2d4264d0a754d3d11c94825fd69d0c7837 (patch)
tree0332502afadae4d4a8c8ec24b5fadbabb0bea956 /miscutils
parent9ca56f9621d9e7265699997d90902fcaf6ed5aad (diff)
downloadbusybox-4d5acd2d4264d0a754d3d11c94825fd69d0c7837.tar.gz
ping: populate icmp_id field for "simple" ping too
The ICMP RFC says that identifier and sequence number may be zero. Having them zero for a Echo message, along with a data of zero's as well will result in a Echo reply message with only zero's. Some NAT implementations seem to get the checksum wrong on these packages. Setting a checksum of 0x0 instead of 0xffff. Through NAT: Internet Control Message Protocol Type: 0 (Echo (ping) reply) Code: 0 Checksum: 0x0000 [incorrect, should be 0xffff] Identifier (BE): 0 (0x0000) Identifier (LE): 0 (0x0000) Sequence number (BE): 0 (0x0000) Sequence number (LE): 0 (0x0000) Data (56 bytes) Data: 000000000000000000000000000000000000000000000000... [Length: 56] Without NAT: Internet Control Message Protocol Type: 0 (Echo (ping) reply) Code: 0 Checksum: 0xffff [correct] Identifier (BE): 0 (0x0000) Identifier (LE): 0 (0x0000) Sequence number (BE): 0 (0x0000) Sequence number (LE): 0 (0x0000) [Request frame: 189] [Response time: 0.024 ms] Data (56 bytes) Data: 000000000000000000000000000000000000000000000000... [Length: 56] And this in turn will make some hardware MAC checksum offloading engines drop the packet. (This was seen with a Synopsis MAC, the same one used in for instance the stmmac Ethernet driver in the linux kernel.) This change can be seen as a workaround for bugs in other layers. But just setting an identifier for the Echo message packet will avoid prodding the hornets nest. function old new delta common_ping_main 424 500 +76 Signed-off-by: Jonas Danielsson <jonasdn@axis.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'miscutils')
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