# Libpcap with Ruby

**URL:** <https://www.ruby-forum.com/t/libpcap-with-ruby/148552>\
**Category:** Rails\
**Created:** [September 14, 2008, 8:38pm UTC](https://www.ruby-forum.com/t/libpcap-with-ruby/148552 "2008-09-14T20:38:54Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![FryShadow](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/4af34b/32.png) [@FryShadow](https://www.ruby-forum.com/u/FryShadow)\
**Post date:** [September 14, 2008, 8:38pm UTC](https://www.ruby-forum.com/t/libpcap-with-ruby/148552/1 "2008-09-14T20:38:54Z")

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I just try some script from fukusima

[http://www.goto.info.waseda.ac.jp/~fukusima/ruby/pcap/examples/](http://www.goto.info.waseda.ac.jp/~fukusima/ruby/pcap/examples/)

When I try to run the script it give a warning

/usr/lib/ruby/site\_ruby/1.8/i686-linux/pcap.so: warning: do not use  
Fixnums as Symbols  
/usr/lib/ruby/site\_ruby/1.8/i686-linux/pcap.so: warning: do not use  
Fixnums as Symbols  
/usr/lib/ruby/site\_ruby/1.8/i686-linux/pcap.so: warning: do not use  
Fixnums as Symbols

Is there any mistake or library that I didn’t include ?

I also try this code :

#!/usr/bin/env ruby

# this line imports the libpcap ruby bindings

require ‘pcaplet’

# create a sniffer that grabs the first 1500 bytes of each packet

$network = Pcaplet.new(‘-s 1500’)

# create a filter that uses our query string and the sniffer we just

made  
$filter = Pcap::Filter.new(‘tcp and dst port 80’, $network.capture)

# add the new filter to the sniffer

$network.add\_filter($filter)

# iterate over every packet that goes through the sniffer

for p in $network

# print packet data for each packet that matches the filter

puts p.tcp\_data if $filter =~ p  
end

and suppose it appear some output after run it, nothing appear ☹

anyone have some solutions ?

thanks in advance

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**Author:** ![FryShadow](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/4af34b/32.png) [@FryShadow](https://www.ruby-forum.com/u/FryShadow)\
**Post date:** [September 14, 2008, 8:40pm UTC](https://www.ruby-forum.com/t/libpcap-with-ruby/148552/2 "2008-09-14T20:40:41Z")

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On 14 Sep 2008, at 19:27, FryShadow wrote:

> Fixnums as Symbols  
> /usr/lib/ruby/site\_ruby/1.8/i686-linux/pcap.so: warning: do not use  
> Fixnums as Symbols
> 
> Is there any mistake or library that I didn’t include ?

that library is just a little old.  
[http://lists.freebsd.org/pipermail/freebsd-ports-bugs/2008-May/141159.html](http://lists.freebsd.org/pipermail/freebsd-ports-bugs/2008-May/141159.html)  
looks like it should fix it ( i did something very similar my self a  
long time ago)

> # create a filter that uses our query string and the sniffer we just
> 
> end
> 
> and suppose it appear some output after run it, nothing appear ☹

did you run it as root ?

The script i had looked more like.

$network.each\_packet do |p|  
…  
end

You don’t need to check if the packet matches the filter - it will  
only get passed to you if it does.

Fred

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**Author:** ![FryShadow](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/4af34b/32.png) [@FryShadow](https://www.ruby-forum.com/u/FryShadow)\
**Post date:** [September 14, 2008, 8:57pm UTC](https://www.ruby-forum.com/t/libpcap-with-ruby/148552/3 "2008-09-14T20:57:08Z")

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Yup, I run the script with root

Look like the library is quite old, is it still working ? 🙂

On Sep 14, 11:39 am, Frederick C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)

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**Author:** ![FryShadow](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/4af34b/32.png) [@FryShadow](https://www.ruby-forum.com/u/FryShadow)\
**Post date:** [September 14, 2008, 9:03pm UTC](https://www.ruby-forum.com/t/libpcap-with-ruby/148552/4 "2008-09-14T21:03:36Z")

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On 14 Sep 2008, at 19:56, FryShadow wrote:

> Yup, I run the script with root
> 
> Look like the library is quite old, is it still working ? 🙂

was working for me a few months ago

Fred