网络协议2天集训

抓包工具安装

Wireshark

Tcpdump

CentOS

yum install tcpdump -y

Ubuntu

apt-get install tcpdump -y

k8s抓包测试环境

查看虚拟网卡veth pair

查看网桥cni0上的虚拟网卡

[master]# yum install bridge-utils -y
[master]# brctl show
bridge name     bridge id               STP enabled     interfaces
cni0            8000.822a0551fe51       no              veth01d2bc26
                                                        veth1b7415be
                                                        veth48059492
                                                        veth6174f7d6
                                                        veth6a56ab55
                                                        vethf3807a14
                                                        vethfbd1eb75
docker0         8000.024218847f20       no

查找容器网卡对应的主机上veth pair

比如，容器tea-6fb46d899f-4zkt2的IP地址是10.244.0.60：

[[email protected] conf]# kubectl describe pod tea-6fb46d899f-4zkt2 | grep IP
IP:           10.244.0.60

它的MAC地址是B2:AD:3A:6E:3A:4F，如下：

[[email protected] conf]# kubectl exec -it tea-6fb46d899f-4zkt2 -- sh
/ $ ip addr
3: [email protected]: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1450 qdisc noqueue state UP 
    link/ether b2:ad:3a:6e:3a:4f brd ff:ff:ff:ff:ff:ff
    inet 10.244.0.60/24 brd 10.244.0.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::b0ad:3aff:fe6e:3a4f/64 scope link 
       valid_lft forever preferred_lft forever

注意，它的eth0序号是17。那么，它对应的主机veth pair虚拟网卡就是vetha1f852ea：

[[email protected] wp]# ip link show | egrep "veth" | awk -F":" '{print $1": "$2}'
14:  [email protected]
15:  [email protected]
16:  [email protected]
17:  [email protected]
18:  [email protected]
19:  [email protected]
20:  [email protected]
21:  [email protected]

当需要抓包时，用tcpdump -i vetha1f852ea即可抓取到容器报文：

[[email protected] wp]# tcpdump -i vetha1f852ea
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on vetha1f852ea, link-type EN10MB (Ethernet), capture size 262144 bytes


19:51:49.847648 IP 10.244.0.60.54477 > 10.96.0.10.domain: 58561+ A? www.baidu.com.default.svc.cluster.local. (57)
19:51:49.847731 IP 10.244.0.60.54477 > 10.96.0.10.domain: 59710+ AAAA? www.baidu.com.default.svc.cluster.local. (57)
19:51:49.849113 IP 10.244.0.58.domain > 10.244.0.60.54477: 59710 NXDomain*- 0/1/0 (150)
19:51:49.849268 IP 10.244.0.58.domain > 10.244.0.60.54477: 58561 NXDomain*- 0/1/0 (150)

跨L3三层vxlan网络抓包

当172.27.0.11主机上访问172.27.16.10主机上的10.244.1.3容器时，IP、MAC地址的获取如下：

Underlay层的IP与MAC地址

在源主机上执行ifconfig，从eth0上即可看到Underlay源IP为172.27.0.11，以及Underlay源MAC为52:54:00:c2:ee:db：

[[email protected] wp]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.27.0.11  netmask 255.255.240.0  broadcast 172.27.15.255
        inet6 fe80::5054:ff:fec2:eedb  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:c2:ee:db  txqueuelen 1000  (Ethernet)
        RX packets 783420  bytes 872472212 (832.0 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 462834  bytes 135019947 (128.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

在目的主机上执行同样步骤，获取到Underlay目的IP为172.27.16.10：

[[email protected] ~]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.27.16.10  netmask 255.255.240.0  broadcast 172.27.31.255
        inet6 fe80::5054:ff:fe4e:502  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:4e:05:02  txqueuelen 1000  (Ethernet)
        RX packets 39103520  bytes 6692916434 (6.2 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1169194048  bytes 117270853999 (109.2 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

需要注意，Underlay目的MAC并不是52:54:00:4e:05:02！Underlay目的MAC实际上是交换机的MAC地址fe:ee:32:07:ea:07：

[[email protected] net]# arp -v
Address                  HWtype  HWaddress           Flags Mask            Iface
gateway                  ether   fe:ee:32:07:ea:07   C                     eth0

这样，Underlay层的4个地址都已得到！

Overlay层的IP与MAC地址

目标容器的IP地址是10.244.1.3，但MAC地址却不能是容器的MAC地址，而必须是flannel.1的地址，因为flannel程序需要将Underlay层剥离，同时修改Overlay层，所以目标MAC地址其实是2a:3c:a0:e1:a9:b6：

[[email protected] net]# arp -v
Address                  HWtype  HWaddress           Flags Mask            Iface
10.244.1.0               ether   2a:3c:a0:e1:a9:b6   CM                    flannel.1

而源IP地址与MAC要根据路由规则来。比如，访问10.244.1.3是通过flannel.1网卡进行的：

[[email protected] net]# ip route
default via 172.27.0.1 dev eth0
10.244.1.0/24 via 10.244.1.0 dev flannel.1 onlink
172.27.0.0/20 dev eth0 proto kernel scope link src 172.27.0.11

而flannel.1虚拟网卡的IP地址则是10.244.0.0：

[[email protected] net]# ifconfig flannel.1
flannel.1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1450
        inet 10.244.0.0  netmask 255.255.255.255  broadcast 10.244.0.0
ether 8e:5c:79:80:cd:cc  txqueuelen 0  (Ethernet)
[[email protected] net]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.27.0.11  netmask 255.255.240.0  broadcast 172.27.15.255
ether 52:54:00:c2:ee:db  txqueuelen 1000  (Ethernet)

它的MAC地址则是8e:5c:79:80 💿 cc。

常见网络编码

ASCII编码

参见wiki，如果打不开，可以查看下表:

控制字符

二进制	十进制	十六进制	缩写	Unicode表示法	脱出字符表示法	名称／意义
0000 0000	0	00	NUL	␀	^@	空字符（Null）
0000 0001	1	01	SOH	␁	^A	标题开始
0000 0010	2	02	STX	␂	^B	本文开始
0000 0011	3	03	ETX	␃	^C	本文结束
0000 0100	4	04	EOT	␄	^D	传输结束
0000 0101	5	05	ENQ	␅	^E	请求
0000 0110	6	06	ACK	␆	^F	确认回应
0000 0111	7	07	BEL	␇	^G	响铃
0000 1000	8	08	BS	␈	^H	退格
0000 1001	9	09	HT	␉	^I	水平定位符号
0000 1010	10	0A	LF	␊	^J	换行键
0000 1011	11	0B	VT	␋	^K	垂直定位符号
0000 1100	12	0C	FF	␌	^L	换页键
0000 1101	13	0D	CR	␍	^M	CR (字符)
0000 1110	14	0E	SO	␎	^N	取消变换（Shift out）
0000 1111	15	0F	SI	␏	^O	启用变换（Shift in）
0001 0000	16	10	DLE	␐	^P	跳出数据通讯
0001 0001	17	11	DC1	␑	^Q	设备控制一（XON 激活软件速度控制）
0001 0010	18	12	DC2	␒	^R	设备控制二
0001 0011	19	13	DC3	␓	^S	设备控制三（XOFF 停用软件速度控制）
0001 0100	20	14	DC4	␔	^T	设备控制四
0001 0101	21	15	NAK	␕	^U	确认失败回应
0001 0110	22	16	SYN	␖	^V	同步用暂停
0001 0111	23	17	ETB	␗	^W	区块传输结束
0001 1000	24	18	CAN	␘	^X	取消
0001 1001	25	19	EM	␙	^Y	连线介质中断
0001 1010	26	1A	SUB	␚	^Z	替换
0001 1011	27	1B	ESC	␛	^[	退出键
0001 1100	28	1C	FS	␜	^\	文件分割符
0001 1101	29	1D	GS	␝	^]	组群分隔符
0001 1110	30	1E	RS	␞	^^	记录分隔符
0001 1111	31	1F	US	␟	^_	单元分隔符
0111 1111	127	7F	DEL	␡	^?	Delete字符

可显示字符

二进制	十进制	十六进制	图形
0010 0000	32	20	(space)
0010 0001	33	21	!
0010 0010	34	22	"
0010 0011	35	23	#
0010 0100	36	24	$
0010 0101	37	25	%
0010 0110	38	26	&
0010 0111	39	27	'
0010 1000	40	28	(
0010 1001	41	29	)
0010 1010	42	2A	*
0010 1011	43	2B	+
0010 1100	44	2C	,
0010 1101	45	2D	-
0010 1110	46	2E	.
0010 1111	47	2F	/
0011 0000	48	30	0
0011 0001	49	31	1
0011 0010	50	32	2
0011 0011	51	33	3
0011 0100	52	34	4
0011 0101	53	35	5
0011 0110	54	36	6
0011 0111	55	37	7
0011 1000	56	38	8
0011 1001	57	39	9
0011 1010	58	3A	:
0011 1011	59	3B	;
0011 1100	60	3C	<
0011 1101	61	3D	=
0011 1110	62	3E	>
0011 1111	63	3F	?

二进制	十进制	十六进制	图形
0100 0000	64	40	@
0100 0001	65	41	A
0100 0010	66	42	B
0100 0011	67	43	C
0100 0100	68	44	D
0100 0101	69	45	E
0100 0110	70	46	F
0100 0111	71	47	G
0100 1000	72	48	H
0100 1001	73	49	I
0100 1010	74	4A	J
0100 1011	75	4B	K
0100 1100	76	4C	L
0100 1101	77	4D	M
0100 1110	78	4E	N
0100 1111	79	4F	O
0101 0000	80	50	P
0101 0001	81	51	Q
0101 0010	82	52	R
0101 0011	83	53	S
0101 0100	84	54	T
0101 0101	85	55	U
0101 0110	86	56	V
0101 0111	87	57	W
0101 1000	88	58	X
0101 1001	89	59	Y
0101 1010	90	5A	Z
0101 1011	91	5B	[
0101 1100	92	5C	\
0101 1101	93	5D	]
0101 1110	94	5E	^
0101 1111	95	5F	_

二进制	十进制	十六进制	图形
0110 0000	96	60	`
0110 0001	97	61	a
0110 0010	98	62	b
0110 0011	99	63	c
0110 0100	100	64	d
0110 0101	101	65	e
0110 0110	102	66	f
0110 0111	103	67	g
0110 1000	104	68	h
0110 1001	105	69	i
0110 1010	106	6A	j
0110 1011	107	6B	k
0110 1100	108	6C	l
0110 1101	109	6D	m
0110 1110	110	6E	n
0110 1111	111	6F	o
0111 0000	112	70	p
0111 0001	113	71	q
0111 0010	114	72	r
0111 0011	115	73	s
0111 0100	116	74	t
0111 0101	117	75	u
0111 0110	118	76	v
0111 0111	119	77	w
0111 1000	120	78	x
0111 1001	121	79	y
0111 1010	122	7A	z
0111 1011	123	7B	{
0111 1100	124	7C
0111 1101	125	7D	}
0111 1110	126	7E	~

网络协议2天集训

Related tags

Overview

抓包工具安装

Wireshark

Tcpdump

k8s抓包测试环境

查看虚拟网卡veth pair

查看网桥cni0上的虚拟网卡

查找容器网卡对应的主机上veth pair

跨L3三层vxlan网络抓包

Underlay层的IP与MAC地址

Overlay层的IP与MAC地址

常见网络编码

ASCII编码

控制字符

可显示字符

Owner

Reproduction process of AlexNet

Code for "Finding Regions of Heterogeneity in Decision-Making via Expected Conditional Covariance" at NeurIPS 2021

Bag of Tricks for Natural Policy Gradient Reinforcement Learning

Leibniz is a python package which provide facilities to express learnable partial differential equations with PyTorch

A script helps the user to update Linux and Mac systems through the terminal

Code for "Multi-Time Attention Networks for Irregularly Sampled Time Series", ICLR 2021.

ML powered analytics engine for outlier detection and root cause analysis.

This is the replication package for paper submission: Towards Training Reproducible Deep Learning Models.

Pytorch Implementation of Zero-Shot Image-to-Text Generation for Visual-Semantic Arithmetic

Code base for the paper "Scalable One-Pass Optimisation of High-Dimensional Weight-Update Hyperparameters by Implicit Differentiation"

fcn by tensorflow

SAN for Product Attributes Prediction

LSTMs (Long Short Term Memory) RNN for prediction of price trends

Source code for CAST - Crisis Domain Adaptation Using Sequence-to-sequence Transformers (Accepted to ISCRAM 2021, CorePaper).

RIFE: Real-Time Intermediate Flow Estimation for Video Frame Interpolation

Instance-level Image Retrieval using Reranking Transformers

Official implementation for (Refine Myself by Teaching Myself : Feature Refinement via Self-Knowledge Distillation, CVPR-2021)

NLMpy - A Python package to create neutral landscape models

This is the 3D Implementation of 《Inconsistency-aware Uncertainty Estimation for Semi-supervised Medical Image Segmentation》