1 of 20

Intercepting Communication

Ethernet

Connor Nelson

Arizona State University

2 of 20

Network

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

3 of 20

Network

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

4 of 20

Network

​

​

What is "Host B"?

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

5 of 20

Network

​

​

What is "Host B"?

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

6 of 20

Network Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

7 of 20

Network Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

8 of 20

Network Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

9 of 20

Network Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

10 of 20

Network Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

11 of 20

Ethernet Packet Structure

6 bytes - Destination Mac Address

6 bytes - Source Mac Address

2 bytes - Type

PACKET

00000000

00000008

00000010

00000018

00000020

00000028

00000030

00000038

00000040

00000048

aa bb cc dd ee ff 11 22 | ......."

33 44 55 66 ?? ?? 00 00 | 3DUf....

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

#

12 of 20

Ethernet Packet Structure

6 bytes - Destination Mac Address

6 bytes - Source Mac Address

2 bytes - Type

PACKET

00000000

00000008

00000010

00000018

00000020

00000028

00000030

00000038

00000040

00000048

aa bb cc dd ee ff 11 22 | ......."

33 44 55 66 ?? ?? 00 00 | 3DUf....

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

#

13 of 20

Ethernet Packet Structure

6 bytes - Destination Mac Address

6 bytes - Source Mac Address

2 bytes - Type

PACKET

00000000

00000008

00000010

00000018

00000020

00000028

00000030

00000038

00000040

00000048

aa bb cc dd ee ff 11 22 | ......."

33 44 55 66 ?? ?? 00 00 | 3DUf....

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

#

14 of 20

Ethernet Packet Structure

6 bytes - Destination Mac Address

6 bytes - Source Mac Address

2 bytes - Type

PACKET

00000000

00000008

00000010

00000018

00000020

00000028

00000030

00000038

00000040

00000048

aa bb cc dd ee ff 11 22 | ......."

33 44 55 66 ?? ?? 00 00 | 3DUf....

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

#

15 of 20

Network Broadcast Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

16 of 20

Network Broadcast Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

17 of 20

Network Broadcast Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

18 of 20

Network Broadcast Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

19 of 20

Network Broadcast Transmission

Host A

eth0

11:22:33:44:55:66

10.0.0.2/16

Host B

eth0

aa:bb:cc:dd:ee:ff

10.0.0.3/16

Host C

eth0

11:aa:22:bb:33:cc

10.0.0.4/16

Bridge

bridge0

f1:fb:f2:f4:fe:fc

vethA

01:02:03:04:05:06

vethB

0a:0b:0c:0d:0e:0f

vethC

01:0a:02:0b:03:0c

#

20 of 20

Broadcast Mac Address

6 bytes - Destination Mac Address

6 bytes - Source Mac Address

2 bytes - Type

PACKET

00000000

00000008

00000010

00000018

00000020

00000028

00000030

00000038

00000040

00000048

ff ff ff ff ff ff 11 22 | ......."

33 44 55 66 ?? ?? 00 00 | 3DUf....

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

00 00 00 00 00 00 00 00 | ........

#