> On 13 Jan 2017, at 10:43, Michael Tuexen <Michael.Tuexen@xxxxxxxxxxxxxxxxx> wrote: > > Your router does NOT change any field in the SCTP packet, but the > SCTP checksum was modified from > Checksum: 0xbaea49e5 (not verified) > to > Checksum: 0xa9a86d3f (not verified) > At least one of these is wrong. Read the tracefiles in wireshark and > enable checksum validation and wireshark will tell you which one is > correct. (That is why I asked for .pcap file instead of a .txt). > > My guess is that the initial checksum is correct and your box middlebox > not only changes the destination address and ttl field and header > checksum in the IP-header (which is expected) but also incorrectly the > SCTP checksum. Since no field in the SCTP packet has changed, the checksum > must be the same. At the server have a look at the SNMP counters: cat /proc/net/sctp/snmp You should find a line staring with SctpChecksumErrors If the number reported there is positive, the node received packets with checksum errors. Best regards Michael > > Best regards > Michael >> On 13 Jan 2017, at 04:29, Sun Paul <paulrbk@xxxxxxxxx> wrote: >> >> Frame 2: 98 bytes on wire (784 bits), 98 bytes captured (784 bits) >> Encapsulation type: Ethernet (1) >> Arrival Time: Jan 6, 2017 16:52:49.662321000 Malay Peninsula Standard Time >> [Time shift for this packet: 0.000000000 seconds] >> Epoch Time: 1483692769.662321000 seconds >> [Time delta from previous captured frame: 0.000179000 seconds] >> [Time delta from previous displayed frame: 0.000179000 seconds] >> [Time since reference or first frame: 0.000179000 seconds] >> Frame Number: 2 >> Frame Length: 98 bytes (784 bits) >> Capture Length: 98 bytes (784 bits) >> [Frame is marked: False] >> [Frame is ignored: False] >> [Protocols in frame: eth:ethertype:ip:sctp] >> Ethernet II, Src: Vmware_81:41:6b (00:50:56:81:41:6b), Dst: >> Vmware_81:a6:a3 (00:50:56:81:a6:a3) >> Destination: Vmware_81:a6:a3 (00:50:56:81:a6:a3) >> Address: Vmware_81:a6:a3 (00:50:56:81:a6:a3) >> .... ..0. .... .... .... .... = LG bit: Globally unique >> address (factory default) >> .... ...0 .... .... .... .... = IG bit: Individual address (unicast) >> Source: Vmware_81:41:6b (00:50:56:81:41:6b) >> Address: Vmware_81:41:6b (00:50:56:81:41:6b) >> .... ..0. .... .... .... .... = LG bit: Globally unique >> address (factory default) >> .... ...0 .... .... .... .... = IG bit: Individual address (unicast) >> Type: IPv4 (0x0800) >> Internet Protocol Version 4, Src: 192.168.206.83, Dst: 192.168.206.66 >> 0100 .... = Version: 4 >> .... 0101 = Header Length: 20 bytes (5) >> Differentiated Services Field: 0x02 (DSCP: CS0, ECN: ECT(0)) >> 0000 00.. = Differentiated Services Codepoint: Default (0) >> .... ..10 = Explicit Congestion Notification: ECN-Capable >> Transport codepoint '10' (2) >> Total Length: 84 >> Identification: 0x0000 (0) >> Flags: 0x02 (Don't Fragment) >> 0... .... = Reserved bit: Not set >> .1.. .... = Don't fragment: Set >> ..0. .... = More fragments: Not set >> Fragment offset: 0 >> Time to live: 63 >> Protocol: SCTP (132) >> Header checksum: 0x1d3d [validation disabled] >> [Good: False] >> [Bad: False] >> Source: 192.168.206.83 >> Destination: 192.168.206.66 >> [Source GeoIP: Unknown] >> [Destination GeoIP: Unknown] >> Stream Control Transmission Protocol, Src Port: 50001 (50001), Dst >> Port: 3868 (3868) >> Source port: 50001 >> Destination port: 3868 >> Verification tag: 0x00000000 >> [Assocation index: 0] >> Checksum: 0xa9a86d3f (not verified) >> >> INIT chunk (Outbound streams: 3000, inbound streams: 3000) >> Chunk type: INIT (1) >> 0... .... = Bit: Stop processing of the packet >> .0.. .... = Bit: Do not report >> Chunk flags: 0x00 >> Chunk length: 52 >> Initiate tag: 0xe79f40cb >> Advertised receiver window credit (a_rwnd): 62464 >> Number of outbound streams: 3000 >> Number of inbound streams: 3000 >> Initial TSN: 176990880 >> IPv4 address parameter (Address: 192.168.206.83) >> Parameter type: IPv4 address (0x0005) >> 0... .... .... .... = Bit: Stop processing of chunk >> .0.. .... .... .... = Bit: Do not report >> Parameter length: 8 >> IP Version 4 address: 192.168.206.83 >> IPv4 address parameter (Address: 192.168.1.83) >> Parameter type: IPv4 address (0x0005) >> 0... .... .... .... = Bit: Stop processing of chunk >> .0.. .... .... .... = Bit: Do not report >> Parameter length: 8 >> IP Version 4 address: 192.168.1.83 >> Supported address types parameter (Supported types: IPv6, IPv4) >> Parameter type: Supported address types (0x000c) >> 0... .... .... .... = Bit: Stop processing of chunk >> .0.. .... .... .... = Bit: Do not report >> Parameter length: 8 >> Supported address type: IPv6 address (6) >> Supported address type: IPv4 address (5) >> ECN parameter >> Parameter type: ECN (0x8000) >> 1... .... .... .... = Bit: Skip parameter and continue >> processing of the chunk >> .0.. .... .... .... = Bit: Do not report >> Parameter length: 4 >> Forward TSN supported parameter >> Parameter type: Forward TSN supported (0xc000) >> 1... .... .... .... = Bit: Skip parameter and continue >> processing of the chunk >> .1.. .... .... .... = Bit: Do report >> Parameter length: 4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
