a_test NetworkStackTests:android.net.apf.ApfTest
https://en.wikipedia.org/wiki/Internet_Protocol_version_4
IPv4 header format
+---------+-------+---------------------------------------+---------------------------------------+---------------------------------------+---------------------------------------+
| Offsets | Octet | 0 | 1 | 2 | 3 |
| Octet | Bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
+---------+-------+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
| 0 | 0 | Version [4] | IHL [>=5] | DSCP | ECN | Total length [>=20, >=4*IHL] |
+---------+-------+-------------------+-------------------+-----------------------------+---------+----+----+----+----------------------------------------------------------------+
| 4 | 32 | Identification | 0 | DF | MF | Fragment offset |
+---------+-------+---------------------------------------+---------------------------------------+----+----+----+----------------------------------------------------------------+
| 8 | 64 | Time to Live | Protocol | Header checksum |
+---------+-------+---------------------------------------+---------------------------------------+-------------------------------------------------------------------------------+
| 12 | 96 | Source address |
+---------+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 16 | 128 | Destination address |
+---------+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 20 | 160 | Options (if IHL > 5) |
| .. | ... | |
| 56 | 448 | |
+---------+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+
https://en.wikipedia.org/wiki/IPv6_packet
Fixed header format
+---------+-------+---------------------------------------+---------------------------------------+---------------------------------------+---------------------------------------+
| Offsets | Octet | 0 | 1 | 2 | 3 |
| Octet | Bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
+---------+-------+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
| 0 | 0 | Version [6] | Traffic class (DSCP 6 + ECN 2 bits) | Flow label |
+---------+-------+-------------------+---------------------------------------+-------------------+---------------------------------------+---------------------------------------+
| 4 | 32 | Payload length | Next header | Hop limit |
+---------+-------+-------------------------------------------------------------------------------+---------------------------------------+---------------------------------------+
| 8 | 64 | Source Address |
| 12 | 96 | |
| 16 | 128 | |
| 20 | 160 | |
+---------+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 24 | 192 | Destination address |
| 28 | 224 | |
| 32 | 256 | |
| 36 | 288 | |
+---------+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+
https://en.wikipedia.org/wiki/ICMPv6
ICMPv6 header (4 bytes): u8 type, u8 code, u16 checksum
(4 bytes in) Message body... (but note in practice it's actually 4 bytes reserved, then 'real' message body at 8 bytes in)
https://en.wikipedia.org/wiki/Transmission_Control_Protocol
TCP segment header
+---------+-------+---------------------------------------+---------------------------------------+---------------------------------------+---------------------------------------+
| Offsets | Octet | 0 | 1 | 2 | 3 |
| Octet | Bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
+---------+-------+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
| 0 | 0 | Source port | Destination port |
+---------+-------+-------------------------------------------------------------------------------+-------------------------------------------------------------------------------+
| 4 | 32 | Sequence number |
+---------+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 8 | 64 | Acknowledgment number (if ACK set) |
+---------+-------+-------------------+-------------------+----+----+----+----+----+----+----+----+-------------------------------------------------------------------------------+
| 12 | 96 | Data Offset | Reserved (zero) | CWR| ECE| URG| ACK| PSH| RST| SYN| FIN| Window size |
+---------+-------+-------------------+-------------------+----+----+----+----+----+----+----+----+-------------------------------------------------------------------------------+
| 16 | 128 | Checksum | Urgent pointer (if URG set) |
+---------+-------+-------------------------------------------------------------------------------+-------------------------------------------------------------------------------+
| 20 | 160 | Options (if data offset > 5. Padded at the end with "0" bits if necessary.) |
| .. | ... | |
| 56 | 448 | |
+---------+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+
https://en.wikipedia.org/wiki/User_Datagram_Protocol
UDP datagram header (8 bytes): be16 source port, destination port, length, checksum
+---------+-------+---------------------------------------+---------------------------------------+---------------------------------------+---------------------------------------+
| Offsets | Octet | 0 | 1 | 2 | 3 |
| Octet | Bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
+---------+-------+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+----+
| 0 | 0 | Source port | Destination port |
+---------+-------+-------------------------------------------------------------------------------+-------------------------------------------------------------------------------+
| 4 | 32 | Length | Checksum |
+---------+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------+
root@athina:~# tcpdump -i eth0 -c 1 -s 65536 -ee -vv -XX 2>/dev/null | sed -r $'s@^\t0x[0-9a-f]{4}: (([0-9a-f]{4} ){0,7}[0-9a-f]{2,4}) .*$@\\1@'
64:87:88:fd:6d:f0 (oui Unknown) > a0:8c:fd:e1:f3:70 (oui Unknown), ethertype IPv6 (0x86dd), length 86: (class 0x20, flowlabel 0xaaab2, hlim 108, next-header TCP (6) payload length: 32) dl-in-f168.1e100.net.5031 > 2620:15c:211:200:7981:81a3:c51b:662c.35954: Flags [.], cksum 0x4d75 (correct), seq 3375638517, ack 3821395769, win 379, options [nop,nop,TS val 4243925517 ecr 1682148025], length 0
a08c fde1 f370 6487 88fd 6df0 86dd 620a
aab2 0020 066c 2607 f8b0 4023 0c0d 0000
0000 0000 00a8 2620 015c 0211 0200 7981
81a3 c51b 662c 13a7 8c72 c934 27f5 e3c5
df39 8010 017b 4d75 0000 0101 080a fcf5
2a0d 6443 8ab9
tcpdump -i eth0 -c 1 -s 65536 -ee -vv -XX 2>/dev/null | sed -r $'s@^\t0x[0-9a-f]{4}: (([0-9a-f]{4} ){0,7}[0-9a-f]{2,4}) .*$@\\1@' | sed -r '/:/!s@ @@g'
Change-Id: I35d23556a0e864c9f2d3982f39f6b32db87d0eb6
4 files changed
