Raw Sockets - UDP client _  REQUIREMENT

Hi, I work for an Internet Service Provider. I have to design a tool to stress Core backbone equipments. We have tools that can generate far more than 1 million packets per second and can spoof multiple IP addresses,  but unfortunately they are not flexible enough to increment a sequence number inside the payload. Thus my request.

Hi arnold, thank for the link. I am after UDP stress testing though.

PA

change the proto to UDP from 6 to 17
http://rhosted.blogspot.com/2009/08/creating-udp-packetip-spoofing-through.html
follow the link to http://www.networksorcery.com/enp/protocol/ip.htm

The issue I'm seeing is that if you alter the source IP as part of the script, you will not receive a response from the packet you sent. So not sure what you are testing.
A spoof is inevitably a one way test of a DoS.
Is the system on which you plan to run the perl script multihomed i.e. all the IPs are present?

arnold,  I don't need a response from the server.
 The server in question is a Syslog server receiving messages from close to 10,000 devices. The server in question has only have one IP. It receives the messages and store them to disk and that is the end of the story.

How would I modify the code  on the link below to send 10 packets instead of one packet?

http://www.perlmonks.org/index.pl?node_id=17576&lastnode_id=63535

I tried the following :

     for ($count = 10; $count >= 1; $count--)
           {
          send(RAW,$packet,0,$destination);
          }
but got error messages.

OK. I solved the loop part of the problem:

What I did is I populated an array:


$src_host_list[0] = '192.168.100.101';
$src_host_list[1] = '192.168.100.102';
$src_host_list[2] = '192.168.100.103';


Then I did:

  for $src_host (@src_host_list)  
  {

   #print "$src_host\n";
    main();
  }

and that generated packets from different sources.

What I need now is to do the same with UDP. I am concerned however about the checksum  calculation ....

The first link references the checksum function as coming from the following:
http://books.google.com/books?id=ESM3CWY5xRYC&pg=PA764&lpg=PA764&dq=checksum+calculation+W.+Richard+Stevens&source=bl&ots=b3wZ1PtEA2&sig=9IKpoX8urZC4DcZ8bMqc7Dt7mA8&hl=en&ei=D9p6TerVBcSx0QG5_rjcAw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBsQ6AEwAA#v=onepage&q&f=false

Thanks.

Referring to the example provided:
http://www.perlmonks.org/index.pl?node_id=17576&lastnode_id=63535

I have been trying to make sense of the line below so I can modify (if necessary) for UDP.

setsockopt(RAW, 0, 1, 1);

Please see below what I have found. Can you please clarify what the meaning are of LEVEL = 0
OPTNAME = 1 and how I would go about choosing options for UDP?


setsockopt SOCKET,LEVEL,OPTNAME,OPTVAL
Sets the socket option requested. Returns undefined if there is an error. Use integer constants provided by the Socket module for LEVEL and OPNAME. Values for LEVEL can also be obtained from getprotobyname. OPTVAL might either be a packed string or an integer. An integer OPTVAL is shorthand for pack("i", OPTVAL).

Pasted from <http://perldoc.perl.org/5.8.8/functions/setsockopt.html> 

DESCRIPTION
      The setsockopt() function shall set the option specified by the option_name argument, at the protocol level specified by the level argument, to the value pointed to by the option_value argument for the socket associated with the file descriptor specified by the socket argument.
      The level argument specifies the protocol level at which the option resides. To set options at the socket level, specify the level argument as SOL_SOCKET. To set options at other levels, supply the appropriate level identifier for the protocol controlling the option. 

[…]
For Boolean options, 0 indicates that the option is disabled and 1 indicates that the option is enabled.
Options at other protocol levels vary in format and name.

Pasted from <http://pubs.opengroup.org/onlinepubs/009695399/functions/setsockopt.html> 

http://books.google.com/books?id=ptSC4LpwGA0C&pg=PA192&lpg=PA192&dq=setsockopt+W.+Richard+Stevens&source=bl&ots=Kq9GUkckLv&sig=L4Gi9vDHoUYa_A5loxA7ClqA_DE&hl=en&ei=QYt7TfeAJ4r3gAes4bTZBw&sa=X&oi=book_result&ct=result&resnum=1&sqi=2&ved=0CBQQ6AEwAA#v=onepage&q=setsock&f=false

Chapter 7.2

You could use getprotobyname with ipproto_UDP to see what the level should be for UDP.
Level 17 is UDP.
setsockopt (socket_filehandle,17,optional,optional) will set the socket for UDP

137 is currently the higher number in use.

#!/usr/bin/perl

$count=0;
print "Level\tDesc\n";
while ($count<=137) {
$level=getprotobynumber($count);
print "$count\t$level \n";
$count+=1;
}

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Hi Arnold, thanks for your help.

I have been able to accomplish the first two objectives successfully, that is:

1- Spoof multiple source IP addresses (10,000) with correct calculation of checksums
2- Keep track of the number of packets sent by each IP using a 32 bit counter.

Now regarding the third objective ( send half a million packets per seconds ) I am a reaching a bottleneck somewhere.  The test server (quad processor 6 GIG of RAM running Ubuntu 64 bit) is only at 25 percent CPU utilization  and 5G free memory, but I am only getting about 85,000 packets per seconds / 88,341,000 bps

I have tried to run the script multiple times, but it seems that the amount of CPU gets divided by the different instances so I never go over 25% CPU utilization.

Is it a limitation of Perl? Problem with the network card buffers?

Any suggestion?

I am not sure, it might be an issue with the tcp/IP stack dealing with how many entries it can keep.
Not sure whether threaded setup might increase your throughput or whether using fork() within perl is a better alternative.

OK, I will have a look. Thanks

Hi Arnold

I got around the performance issue by:

1) generating udp traffic using the perl script
2_recording the outpug using tcpdump
3) replaying it using a third party tool bittwist.

I managed to generate around 350,000 pps  (a bit short of my objective ) but by combining two servers, I  should be able to get the job done.

Thanks your input

PA