View
76
Download
0
Category
Preview:
DESCRIPTION
Network Packet Generator. Final Presentation Presenting: Igor Brevdo Eugeney Ryzhyk, Supervisor: Mony Orbach. Agenda. Introduction Packet generator role in networking Packet Generator in details Usage of Packet Generator Results. Project goals. - PowerPoint PPT Presentation
Citation preview
1
Network Packet GeneratorFinal PresentationPresenting:
Igor Brevdo
Eugeney Ryzhyk,
Supervisor: Mony Orbach
2
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
3
Project goals
• Building network packet generator (using ML310 board and Linux OS as a platform).
• Allow customization and fine-tuning of the various packet generation parameters at different network stack layers (Ethernet frame, IP packet, TCP/UDP packet)
4
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
5
The use of packet generator in networking (1)
• Test resistance and durability of networks connecting/serving devices as routers, servers or switches – Are some sort of packets get lost in particular
device ?– What is the maximum rate of packets per
second that a specific router can route ?– What is maximum open connections a target
server can handle ?
6
The use of packet generator in networking (2)
• Physical device transmitting capability
– Test the maximum speed of physical networking card attached to system
• Creation of artificial packet saturation in particular network
• Test firewall for penetrability (port scan)
7
General approach to solution (1)
• On one hand, freedom of OS constraints such as – Will not use OS TCP/IP stack– Eliminate context switches– Complete freedom in packet crafting– Talking to network device directly
• On other hand, exploit the full advantages of running within OS– Use running environment– Use networking services and data structures
8
General approach to solution (2)
• As in our case the OS is Linux, the self evident solution is use a kernel loadable modules mechanism
• That way the kernel networking stack is not forced but offered to our use (skb buffers, netdevice structure)
• Running in kernel mode – no context switches and system calls overpays
• Direct access to network card• Accurate timing measurement• On fly inserting to running kernel
9
General approach to solution (3)
• Disadvantages to this approach– Various libraries are not provided when
running kernel code – not even C standard library. Only kernel API can be used
– The debugging is tricky: no debugger for kernel, only special printk() function
– How to tell kernel module what we want?
10
Project requirements (1) A Packet Generator should be able to craft standard
networking packets of type UDP, TCP, IP, Ethernet
Full control over UDP and TCP ports should be provided to user of Packet Generator
Full control over IP addresses should be provided to user of Packet Generator
UDP and TCP and IP checksums must be calculated and set in packets headers
A user should be able to insert a data in packets which can allow faster packet recognition
Ethernet header IP header TCP header Data
11
Project requirements (2) Provide a way to configure a stream of packets of
particular protocol type when both IP addresses and UDP/TCP addresses limits are set by user.
Packet Generator will provide for user configuration
number of packets in stream, the desired rate (speed) of packets network device to use for transmitting.
Easy to use and detailed user interface which runs on PC will be provided to configure Packet Generator tasks
12
Development Environment (1) Xilinx ML310 Two PowerPC 405 cores 256 MB DDR Onboard 10/100 Ethernet NIC Standard output through COM
serial connection (on RS-232 cable)
Sansa Flash as storage device Cross LAN network cable Linux with kernel 2.4.20 Bash shell
13
Development Environment (2) Monta Vista development environment
Cross compilation for PPC 405
Linux tools on Windows like bash, make and gcc
Linux kernel sources – must be used to compile the kernel module
Microsoft Visual studio – developing Packet Generator GUI and COM serial communicator
Ethereal Network sniffer – great (and free) tool for receiving and checking the packet streams
Putty – free program for serial communication with the target while debugging
14
AgendaAgenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
15
Implementation: GUI agent on PC
Written in MFC
Provides an easy interface for scenario configuration
Presents the results output
Serial communication with target
17
Implementation: kernel-mode part of Packet Generator
Implemented as kernel loadable module
Communicates with user mode through /proc file system
Uses SK buffers to build networks packets
Activates NIC directly through net device interface
18
Communicating with kernel through /proc file system
in-memory file system used to provide file based communication with the kernel. o Any kernel component that
wants to communicate with the user can create a file under the proc and that can be used to exchange data
Common operations like reading from or writing to file are accessible to all user processes.
All the files under the proc file system reside in memory.
19
Building the packets with help of SK buffers (1)
• "SKB" is the most fundamental data structure in the Linux networking code. – Every packet sent or
received is handled using this data structure.
• Skbuffers are held within list data structure
20
Building the packets with help of SK buffers (2)
• Four pointers that responsible for data handling inside sk buffer
• Functions that manipulate these pointers are in heavy use by packet engine and are participate in building of every packet,
22
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
23
Usage of Packet Generator (1)
• Step 0: Set up ml310 board (power, memory, network connection, serial COM connection)
• Step 1: Run Packet Generator GUI from the pc and turn on board’s power supply.
24
Usage of Packet Generator: starting serial connection
• Step 2: Invoke serial connection– Connect/Disconnect will
establish serial connection to board and also will start kernel booting and Linux OS will load.
25
Usage of Packet Generator: Module initialization
• Step 3: Inserting module and initialization – Pressing Init Generator
button will insert Packet Generator module into running kernel and bring up the network card
26
Scenario configuration
• Step 4: Configure the scenario– choose transport layer
protocol type TCP or UDP
– Choose minimum and maximum ports numbers (destination and source)
– Choose minimum and maximum IP addresses (destination and source)
27
Scenario configuration• Step 4(continued): Scenario
configuration– Choose MAC layer addresses,
destination and source
– Insert the data of the generated packets
– General configurations. • network device to use • number of packets to
generate• a time gap between every two
packets • Randomization flags: random
transportation ports, random IP addresses.
28
Running the scenario• Step 5: Run the scenario
• Start ethereal sniffer on destination machine and press start to begin the generation and sending process.
• When the scenario will stop running the packet generator will print it’s performance results:– Time to do the job consisting of idle and
working time– Packets length in [Bytes]– Sending rate in [packets/second]– Speed of sending in [bytes/second]
30
Another example (TCP packet)
• Here is another example
• TCP protocol is chosen
• the increment of IP addresses can be seen.
32
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
33
Results (1)
• Time unit for sending one packet consists of:SK buffer allocationPopulation of buffer by packet’s
data, including adjustment of header fields. (work time)
Waiting for device and sending it through device or if device is busy going to next iteration (work time)
Checking whether process rescheduling is needed (goes to idle time)
Waiting inter packet gap time it done by user (goes to idle time)
34
Results: Transmitting rate as function of packets number
Sending rate (small packets)
0
2000000
4000000
6000000
8000000
10000000
12000000
10 100 1000 10,000 100,000 1,000,000
number of packets
bits
per
sec
ond
length 70 B
10 Mb per second
35
Results: Controlling the speed by artificial gaps between packets
Accuracy of artificial rate setting
0
10,000,000
20,000,000
30,000,000
40,000,000
50,000,000
60,000,000
10,000 100,000 1,000,000
Gap between packet [nsec]
Bits
per
sec
ond
Measured rate
Ideal rate
36
Improvements and expansions
o Trying the alternative to communication with kernel module through it’s own API and not by /proc files.
o Use of skb clones to utilize the sending speed of the packets
o Rewrite the packet generator for current kernel (2.6.X)
o Usage of packet generator with specially designed devices
o Usage of packet generator in large networks
o Usage of packet generator in high speed networks
37
Bibliography
• TCP/IP Illustrated Volume 1 – The Protocols, Richard Stevens
• Linux Device Drivers, 2nd edition – Alessandro Rubini, Jonathan Corbet
• Linux Kernel Sources (version 2.4)
• Linux Kernel Modules Programming Guide
• Transmission Control Protocol, RFC 793• http://tools.ietf.org/html/rfc793
• Proc file system guide• http://www.geocities.com/ravikiran_uvs/articles/proc.html
• How SKB work• http://vger.kernel.org/~davem/skb_data.html
Recommended