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

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