Re: Problem on SCTP

From: Xin Long
Date: Mon Feb 27 2017 - 10:07:45 EST

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On Mon, Feb 27, 2017 at 5:01 PM, Sun Paul <paulrbk@xxxxxxxxx> wrote:
> Hi, can I confirm that the problem is on the Linux router itself or on
> both server and client?
>
try with a new kernel in router, like build and install a upstream
kernel on your route machine.

git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git

https://kernelnewbies.org/KernelBuild :
part "Setting up your kernel configuration" and
part "Building the kernel"

> On Thu, Feb 23, 2017 at 2:07 PM, Xin Long <lucien.xin@xxxxxxxxx> wrote:
>> On Thu, Feb 23, 2017 at 1:30 PM, Sun Paul <paulrbk@xxxxxxxxx> wrote:
>>> does this fixed in RHEL7?
>> yes, I think so.
>>
>>>
>>> On Wed, Feb 22, 2017 at 11:03 AM, Xin Long <lucien.xin@xxxxxxxxx> wrote:
>>>> On Wed, Feb 22, 2017 at 10:29 AM, Sun Paul <paulrbk@xxxxxxxxx> wrote:
>>>>> Hi Xin
>>>>>
>>>>> do you mean we need to patch the kernel?
>>>> Yups, pls comment on that bz if it's really needed for your env.
>>>> A z-stream kernel may be available for that issue soon.
>>>>
>>>> Thanks.
>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Feb 22, 2017 at 10:00 AM, Xin Long <lucien.xin@xxxxxxxxx> wrote:
>>>>>> On Wed, Feb 22, 2017 at 9:12 AM, Sun Paul <paulrbk@xxxxxxxxx> wrote:
>>>>>>> Hi
>>>>>>>
>>>>>>> the router is actually is a linux running on RHEL6.8
>>>>>>> (2.6.32-642.4.2.el6.x86_64). it uses iptables to do SNAT aand DNAT
>>>>>>> forward.
>>>>>> https://bugzilla.redhat.com/show_bug.cgi?id=1412038
>>>>>>
>>>>>> sctp_manip_pkt->sctp_compute_cksum:
>>>>>> struct sctphdr *sh = sctp_hdr(sub);
>>>>>>
>>>>>> But in rhel6, skb->transport_header is not yet set at that time.
>>>>>> This patch should be backported into rhel6.
>>>>>>
>>>>>> commit 21d1196a35f5686c4323e42a62fdb4b23b0ab4a3
>>>>>> Author: Eric Dumazet <edumazet@xxxxxxxxxx>
>>>>>> Date: Mon Jul 15 20:03:19 2013 -0700
>>>>>>
>>>>>> ipv4: set transport header earlier
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> On Tue, Feb 21, 2017 at 11:53 PM, Xin Long <lucien.xin@xxxxxxxxx> wrote:
>>>>>>>> On Tue, Feb 21, 2017 at 12:26 PM, Sun Paul <paulrbk@xxxxxxxxx> wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> sorry to get back late, the platform is running on KVM. and this
>>>>>>>>> problem is resolved by moving to VMware environment, however, a new
>>>>>>>>> problem is coming out, we noticed that the HB REQ is being ABORT from
>>>>>>>>> client.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> 03:32:35.233572 IP 10.165.250.22.3868 > 192.168.2.13.40001: sctp (1)
>>>>>>>>> [HB REQ] (from server to sctp router)
>>>>>>>>> 03:32:35.233603 IP 192.168.2.14.3868 > 192.168.2.13.40001: sctp (1)
>>>>>>>>> [HB REQ] (from sctp router to client)
>>>>>>>>> 03:32:35.233852 IP 192.168.2.13.40001 > 192.168.2.14.3868: sctp (1)
>>>>>>>>> [ABORT] (from client to sctp router)
>>>>>>>>>
>>>>>>>>> 03:32:37.928679 IP 10.165.250.22.3868 > 192.168.2.13.40001: sctp (1) [HB REQ]
>>>>>>>>> 03:32:37.928717 IP 192.168.2.14.3868 > 192.168.2.13.40001: sctp (1) [HB REQ]
>>>>>>>>> 03:32:37.929247 IP 192.168.2.13.40001 > 192.168.2.14.3868: sctp (1) [ABORT]
>>>>>>>>>
>>>>>>>>> For the above packet flow, 10.165.250.22 is the server and
>>>>>>>>> 192.168.2.13 is the client, the server 10.165.250.22 sends HB REQ to
>>>>>>>>> client 192.168.2.13 through 192.168.2.14 (the SCTP router), and the
>>>>>>>>> SCTP router change the src address before forward the HB REQ to the
>>>>>>>>> client.
>>>>>>>>>
>>>>>>>>> But somehow the client is ABORT the HB REQ, any idea? is it related to
>>>>>>>>> the HEARTBEAT information? or the checksum again>?
>>>>>>>> The incorrect checksum won't cause ABORT, but the abnormal HB REQ
>>>>>>>> could be, if HB information was modified when calculating the checksum
>>>>>>>> on router, the ABORT may be caused in client process.
>>>>>>>>
>>>>>>>> is your SCTP router linux ? if yes, what's the kernel version ?
>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Fri, Jan 13, 2017 at 9:19 PM, Michael Tuexen
>>>>>>>>> <Michael.Tuexen@xxxxxxxxxxxxxxxxx> wrote:
>>>>>>>>>>> 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
>>>>>>>>>>>
>>>>>>>>>>> --
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>>>>>>>>>>
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In reply to: Sun Paul: "Re: Problem on SCTP"
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