# MAPT fragments issue ### mapt debug command echo config nat46MAP debug 10 > /proc/net/nat46/control dmesg -n 8 tcpdump -i nat46MAP -w /data_save/udp_download_1600_debug.pcap tcpdump -i nat46MAP -w /data_save/udp_upload_1600_debug3.pcap ### checksum 計算 https://blog.csdn.net/qy532846454/article/details/7010852 # mapt kernel https://lore.kernel.org/netdev/20191008120432.GB2761030@kroah.com/T/ http://www.embeddedlinux.org.cn/linux_net/0596002556/understandlni-CHP-22-SECT-2.html#understandlni-CHP-22-SECT-2.6 https://lore.kernel.org/netdev/20191008120432.GB2761030@kroah.com/T/ http://www.embeddedlinux.org.cn/linux_net/0596002556/understandlni-CHP-2-SECT-1.html ![](https://i.imgur.com/VcrVRaa.png) ![](https://i.imgur.com/vWmGamV.png) ![](https://i.imgur.com/5XmZBI3.png) https://www.packetmania.net/en/2021/12/26/IPv4-IPv6-checksum/ ## TCP/UDP Header Checksum For TCP segment and UDP datagram, both have 16-bit header checksum fields used for error-checking by the destination host. The checksum computing algorithm is the same as the IP header, except for the difference of covered data. Here the checksum is calculated over the whole TCP/UDP header and the payload, plus a pseudo-header that mimics the IPv4 header as shown below: ### ipv4 pseudo-header for tcp,udp ![](https://i.imgur.com/181D65K.png) For IPv6 TCP segment and UDP datagram header checksum computing, the pseudo-header that mimics the IPv6 header is shown below ### ipv6 tcp pseudo-header for tcp, udp ![](https://i.imgur.com/HKgiPUh.png) http://hanteye01.blog.fc2.com/blog-entry-2.html ## Structure of an IPv6 Packet 一個IPv6封包包含一個IPv6 header、 零到多個Extension Headers（擴充表頭）以及一個upper-layer protocol data unit（上層通訊協定資料單元）。請注意： IPv6封包的payload（承載資料）是由Extension Headers及Upper-Layer Protocol Data Unit組成。最大長度為65,535 bytes。 ![](https://i.imgur.com/pCSPP2I.png) ![](https://i.imgur.com/5SEyPE3.png) ![](https://i.imgur.com/BMGGE8v.png) **IPv6 Header** 永遠存在且固定長度40 bytes。 **Extension Header** 零到多個擴展表頭，並且長度是可變動的。IPv6表頭中的Next Header欄位表示下一個擴展表頭的類型。在每個擴展表頭中還有另一個Next Header欄位，用來表示下一個擴展表頭的類型。最後一個擴展表頭的Next Header欄位表示上層通訊協定類型或為No next header(59)（當上層資料不存在時）。 **Upper-Layer Protocol Data Unit** 上層資料，例如ICMPv6、UDP或TCP。 ![](https://i.imgur.com/CHKLdKg.png) **Fragment Header** 在 IPv6 中，只有來源節點可對payload 進行分段。 當發送的封包大於path MTU時，則必須用Fragment Header對封包做分段處理後，再一個個發送分段好的片段封包。最後由目的節點將所有片段封包重組成原始封包。可在上一個Header的 Next Header 欄位中將值設為 44 來識別此Header。 Image 39 **Next Header** 用來識別下一個表頭的類型。 **Fragment Offset** 長度13 bits，8 bytes為單位。片段位移： 相對於分段前的原始封包的可分段部分的開始位置。 **More Fragments** 值為1代表此分段後還有分段。值為0代表此分段為最後一個分段。 **Identification** 當有大封包需要做分段處理時，發送端會對每個需要分段的原始封包產生不同的識別值，並且把這個識別值填入每個分段好后的片段封包的Identification欄位。Identification欄位主要是便於目的節點區別並重組不同的片段封包成為原始封包，然後再做進一步的處理。 **IPv6 Fragmentation Process 封包切割處理** 在將 IPv6 封包分段前，先將它分成不可分段部分和可分段部分： **不可分段部分** 由於此分段部分為每個router必須處理的部分，即使做了分段，每個分段後的封包必須重複包含此部分。 它包含 IPv6 表頭、Hop-by-Hop Options表頭、中間目的的 Destination Options表頭以及 Routing表頭組成。 **可分段部分** 此分段部分包含僅被最終目的節點處理的擴展表頭及上層 PDU。 **分段後的片段封包由以下部分組成：** **（1） 不可分段部分** IPv6表頭的Payload Length欄位值須設為此片段封包的承載長度。由於分段後加入了Fragment擴展表頭，不可分段部分的最後一個擴展表頭的Next Header欄位須設為Fragment擴展表頭的識別值44。請注意，由於做分段時不可分段部分的最後一個擴展表頭的Next Header欄位已經被更改，所以重組片段成原始封包時必須回復這個欄位值。 **（2） Fragment Header 它的內容如下：** - Next Header欄位設為原始封包的可分段部分的第一個擴展表頭的識別值。當目的節點將片段封包重組成原始封包時，此欄位用來回復不可分段部分的最後一個擴展表頭的Next Header的原始設定值。 - Fragment Offset欄位設為位移值（8 bytes為單位）: 相對於原始封包的可分段部分的開始位置。 - 如果此片段為最後一個，則M flag欄位設為0。其它片段則設M flag欄位為1。 - 設定Identification欄位。 ![](https://i.imgur.com/fRK4dg9.png) ![](https://i.imgur.com/EOq23uP.png) ![](https://i.imgur.com/R2futXA.png) ![](https://i.imgur.com/LW9eYcF.png) ### kernel 4.4 主要的變動 https://lore.kernel.org/netdev/20191008120432.GB2761030@kroah.com/T/ ## nat46 module github information https://github.com/ayourtch/example-nat46/blob/master/nat46-core.c https://github.com/ayourtch/nat46/issues/24 ![](https://i.imgur.com/X2391l7.png) ### nat46_ipv4_in --> ip6_update_csum (52-sc_ipv4_ignore_option.patch) ![](https://i.imgur.com/HA1BpDU.png) ### nat46_ipv6_in ![](https://i.imgur.com/fK66Wjz.png) #define NEXTHDR_TCP 6 /* TCP segment. */ #define NEXTHDR_UDP 17 /* UDP message. */ ![](https://i.imgur.com/KOB5F2J.png) ### spf12 從 dut "ping 206.1.1.116 -s 1600" crash ![](https://i.imgur.com/VYzb1i1.png) ### test howto #### 產生1600byte 內容為00 dd if=/dev/zero of=1600_byte.bin bs=1600 count=1 dd if=/dev/zero bs=1 count=1600 | tr "\000" "\377" >paddedFile.bin ### ipv6 down-stream #### in ipv6 server (10.1.1.213) to set up tcp or udp server nc -lu fd00::ffff:ce:101:7400:0 5001 < 1600_byte.bin nc -l fd00::ffff:ce:101:7400:0 5001 < 1600_byte.bin #### dut linux lan client nc -lu 206.1.1.116 5001 > udp_download_file nc -l 206.1.1.116 5001 > tcp_download_file ### ipv4 down-stream #### in ipv6 server (10.1.1.213) to set up tcp or udp server nc -lu fd00::ffff:ce:101:7400:0 5001 > udp_upload_file nc -l fd00::ffff:ce:101:7400:0 5001 > tcp_upload_file #### dut linux lan client nc -lu 206.1.1.116 5001 < 1600_byte.bin nc -l 206.1.1.116 5001 < 1600_byte.bin #### downstream v6 1600 byte (1448 ) root@SAX1V1R:/data_save# [ 1430.672451] nat46_ipv4_input packet [ 1430.672475] nat46_ipv4_input protocol: 17, len: 29, flags: 01 [ 1430.674747] ip_hdrlen = 20, l4_hdrlen = 8 [ 1430.674747] [ 1430.680673] xlate_map_v4_to_v6: ntohs(l4id): 7ffe psid_bits_len: 6, rule psid-offset: 6, psid: 63 [ 1430.680673] [ 1430.686045] Src addr 10.0.3.2 to 2001:0db8:0000:02fc:0000:0a00:0302:003f [ 1430.686045] [ 1430.696365] Dst addr 206.1.1.116 to fd00:0000:0000:ffff:00ce:0101:7400:0000 [ 1430.696365] [ 1430.704606] [nat46] pairs_xlate_v4_to_v6_outer result: src 0 dst 0 [ 1430.713206] about to send v6 packet, flags: 00 [ 1430.719273] [nat46] not set DF [ 1430.719273] [ 1430.725184] dev=br-wan skb_len=208 fd00:0000:0000:ffff:00ce:0101:7400:0000 -> 2001:0db8:0000:02fc:0000:0a00:0302:003f [ 1430.725188] dev=br-wan skb_len=1496 fd00:0000:0000:ffff:00ce:0101:7400:0000 -> 2001:0db8:0000:02fc:0000:0a00:0302:003f [ 1430.725192] ipv6_input fragment id: B88FCB14 [ 1430.728139] ipv6_input fragment id: B88FCB14 [ 1430.754252] nat46_ipv6_input packet [ 1430.758172] nat46_ipv6_input fd00:0000:0000:ffff:00ce:0101:7400:0000 -> 2001:0db8:0000:02fc:0000:0a00:0302:003f next hdr: 44, len: 1496, is_fragment: 1 [ 1430.758172] [ 1430.761391] reasm_payload_len = 1608, l3_infrag_payload_len = 1456 [ 1430.761391] [ 1430.776658] Fragment ID: B88FCB14 [ 1430.784112] 00000000: 11 00 00 01 14 CB 8F B8 13 89 7F FE 06 48 AF 10 .............H.. [ 1430.787597] 00012480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.795761] 00124800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.803998] 00136C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.812250] 01248000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.820495] 0125A480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.828742] 0136C800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.836992] 0137EC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.845235] 12480000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.853477] 12492480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.861729] 125A4800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.869975] 125B6C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.878224] 136C8000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.886468] 136DA480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.894710] 137EC800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.902961] 137FEC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.911208] 24800000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.919454] 24812480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.927701] 24924800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.935960] 24936C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.944191] 25A48000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.952448] 25A5A480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.960690] 25B6C800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.968934] 25B7EC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.977180] 36C80000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.985425] 36C92480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1430.993668] 36DA4800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.001918] 36DB6C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.010166] 37EC8000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.018419] 37EDA480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.026660] 37FEC800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.034908] 37FFEC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.043148] 48000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.051398] 48012480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.059646] 48124800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.067892] 48136C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.076138] 49248000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.084381] 4925A480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.092632] 4936C800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.100878] 4937EC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.109125] 5A480000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.117371] 5A492480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.125617] 5A5A4800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.133859] 5A5B6C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.142110] 5B6C8000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.150357] 5B6DA480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.158603] 5B7EC800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.166849] 5B7FEC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.175097] 6C800000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.183344] 6C812480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.191590] 6C924800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.199859] 6C936C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.208097] 6DA48000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.216339] 6DA5A480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.224587] 6DB6C800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.232840] 6DB7EC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.241088] 7EC80000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.249322] 7EC92480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.257562] 7EDA4800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.265809] 7EDB6C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.274051] 7FEC8000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.282300] 7FEDA480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.290548] 7FFEC800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.298793] 7FFFEC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.307042] 80000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.315287] 80012480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.323530] 80124800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.331780] 80136C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.340027] 81248000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.348274] 8125A480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.356519] 8136C800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.364761] 8137EC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.373013] 92480000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.381260] 92492480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.389505] 925A4800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.397752] 925B6C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.406000] 936C8000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.414241] 936DA480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.422492] 937EC800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.430739] 937FEC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.438987] A4800000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.447232] A4812480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.455479] A4924800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.463721] A4936C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.471972] A5A48000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.480218] A5A5A480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.488465] A5B6C800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.496710] A5B7EC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.504958] B6C80000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.513199] B6C92480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.521451] B6DA4800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.529697] First fragment, frag_off: 2000, frag id: 739B orig frag_off: 0001 [ 1431.537949] Dst addr 2001:0db8:0000:02fc:0000:0a00:0302:003f to 10.0.3.2 [ 1431.537949] [ 1431.545149] Src addr fd00:0000:0000:ffff:00ce:0101:7400:0000 to 206.1.1.116 [ 1431.545149] [ 1431.553304] [nat46] pairs_xlate_v6_to_v4_outer result src 0 dst 0 [ 1431.561901] udp: 35091 -> 65151 [ 1431.561901] [ 1431.567973] afu : skb_set_transport_header with fragment 28 [ 1431.572655] about to send v4 packet, flags: 00 [ 1431.577969] nat46_ipv6_input packet [ 1431.582462] nat46_ipv6_input fd00:0000:0000:ffff:00ce:0101:7400:0000 -> 2001:0db8:0000:02fc:0000:0a00:0302:003f next hdr: 44, len: 208, is_fragment: 1 [ 1431.582462] [ 1431.585875] Fragment ID: B88FCB14 [ 1431.601128] 00000000: 11 00 05 A8 14 CB 8F B8 00 00 00 00 00 00 00 00 ................ [ 1431.604346] 00012480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.612509] 00124800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.620757] 00136C80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.629002] 01248000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.637248] 0125A480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.645495] 0136C800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.653737] 0137EC80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.661989] 12480000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.670234] 12492480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ [ 1431.678481] 125A4800: 00 00 00 00 00 00 00 00 ........ [ 1431.686729] Not first fragment, frag_off: 00B5, frag id: 739B orig frag_off: 05A8 [ 1431.694976] Dst addr 2001:0db8:0000:02fc:0000:0a00:0302:003f to 10.0.3.2 [ 1431.694976] [ 1431.702524] Src addr fd00:0000:0000:ffff:00ce:0101:7400:0000 to 206.1.1.116 [ 1431.702524] [ 1431.710687] [nat46] pairs_xlate_v6_to_v4_outer result src 0 dst 0 [ 1431.719276] afu : skb_set_transport_header with fragment 28 [ 1431.725350] about to send v4 packet, flags: 00 [ 1431.730867] nat46_ipv4_input packet [ 1431.735259] nat46_ipv4_input protocol: 1, len: 576, flags: 00 [ 1431.738629] ip_hdrlen = 20, l4_hdrlen = 8 [ 1431.738629] [ 1431.744531] ICMP translated to dest port 0, and src port 0. [ 1431.749925] xlate_map_v4_to_v6: IPv4 address 192.168.1.1 outside of MAP domain 10.0.3.0/24 [ 1431.755393] Dst addr 206.1.1.116 to fd00:0000:0000:ffff:00ce:0101:7400:0000 [ 1431.755393] [ 1431.763721] [nat46] pairs_xlate_v4_to_v6_outer result: src -1 dst 0 [ 1431.772313] [nat46] Could not find a translation pair v4->v6 [ 1431.778394] net_ratelimit: 20 callbacks suppressed [ 1431.778395] [nat46] Could not translate v4->v6 #### up-stream v4 1600 --> second fragment source ip not the as first one root@SAX1V1R:~# [ 1990.694585] nat46_ipv4_input packet [ 1990.694610] nat46_ipv4_input protocol: 17, len: 1500, flags: 09 [ 1990.696874] ip_hdrlen = 20, l4_hdrlen = 8 [ 1990.696874] [ 1990.702802] **xlate_map_v4_to_v6: ntohs(l4id): cff3 psid_bits_len: 6, rule psid-offset: 6, psid: 63** [ 1990.702802] [ 1990.708346] **Src addr 10.0.3.2 to 2001:0db8:0000:02fc:0000:0a00:0302:003f ** [ 1990.708346] [ 1990.718675] Dst addr 206.1.1.116 to fd00:0000:0000:ffff:00ce:0101:7400:0000 [ 1990.718675] [ 1990.726920] [nat46] pairs_xlate_v4_to_v6_outer result: src 0 dst 0 [ 1990.735511] about to send v6 packet, flags: 00 [ 1990.741576] [nat46] not set DF [ 1990.741576] [ 1990.746020] nat46_ipv4_input packet [ 1990.750429] nat46_ipv4_input protocol: 17, len: 148, flags: 09 [ 1990.753911] ip_hdrlen = 20, l4_hdrlen = 8 [ 1990.753911] [ 1990.759810]** xlate_map_v4_to_v6: ntohs(l4id): 0000 psid_bits_len: 6, rule psid-offset: 6, psid: 0** [ 1990.759810] [ 1990.765292] **Src addr 10.0.3.2 to 2001:0db8:0000:0200:0000:0a00:0302:0000** [ 1990.765292] [ 1990.775616] Dst addr 206.1.1.116 to fd00:0000:0000:ffff:00ce:0101:7400:0000 [ 1990.775616] [ 1990.783776] [nat46] pairs_xlate_v4_to_v6_outer result: src 0 dst 0 [ 1990.792368] about to send v6 packet, flags: ![](https://i.imgur.com/AQ8Yv0M.png)