Download Final Presentation - High Speed Digital Systems Laboratory

Network Packet Generator
Final Presentation
Presenting:
Igor Brevdo
Eugeney Ryzhyk,
Supervisor: Mony Orbach
1
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
2
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)
3
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
4
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 ?
5
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)
6
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
7
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
8
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?
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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
10
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
11
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
12
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
13
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
14
Implementation: GUI agent on PC
 Written in
MFC
 Provides an
easy interface
for scenario
configuration
 Presents the
results output
 Serial
communicatio
n with target
15
Implementation: user-mode agent
on ML310
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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
17
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.
18
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
19
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,
20
Implementation: kernel-mode part
of Packet Generator
21
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
22
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.
23
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.
24
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
25
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)
26
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.
27
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]
28
Inspecting the results
29
Another example (TCP packet)
• Here is another
example
• TCP protocol is
chosen
• the increment of IP
addresses can be
seen.
30
Another example (cont)
31
Agenda
• Introduction
• Packet generator role in networking
• Packet Generator in details
• Usage of Packet Generator
• Results
32
Results (1)
• Time unit for sending one packet
consists of:
 SK buffer allocation
 Population 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)
33
Results: Transmitting rate as
function of packets number
Sending rate (small packets)
12000000
bits per second
10000000
8000000
length 70 B
6000000
10 Mb per second
4000000
2000000
0
10
100
1000
10,000
100,000 1,000,000
number of packets
34
Results: Controlling the speed by
artificial gaps between packets
Accuracy of artificial rate setting
60,000,000
Bits per second
50,000,000
40,000,000
Measured rate
30,000,000
Ideal rate
20,000,000
10,000,000
0
10,000
100,000
1,000,000
Gap between packet [nsec]
35
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
36
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
37