From: Bryan Richardson <btricha@...>
Date: 2008-01-16T14:53:29+09:00
Subject: Re: Problem with IPAddr

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Gary,

Thanks for the reply.  Here's what I get when I try something else:

irb(main):001:0> require 'ipaddr'
=> true
irb(main):002:0> net_1 = IPAddr.new("192.168.0.0/16")
=> #<IPAddr: IPv4:192.168.0.0/255.255.0.0>
irb(main):003:0> net_2 = IPAddr.new("192.168.101.0/24")
=> #<IPAddr: IPv4:192.168.101.0/255.255.255.0>
irb(main):004:0> net_1.include?(net_2)
=> true
irb(main):005:0> net_2.include?(net_1)
=> false
irb(main):006:0>

Makes sense I guess.  Is there any way to tell IPAddr to look at it as a
network instead of as an address?  I have a situation where I may come
across an address (ending in .0, so defining a network) where the netmask
isn't given, so I assign it as a small network (say /29).  Later on I may
come across it again, this time with the netmask defined (say /16), and I
want to merge the first one into the second one.  Therefore, each time I add
a new network to my database, I compare it to the existing ones to see if
any should be merged.  Any suggestions?  Thanks!! -- BTR

On Jan 15, 2008 10:32 PM, Gary Wright <gwtmp01@mac.com> wrote:

>
> On Jan 16, 2008, at 12:02 AM, Bryan Richardson wrote:
>
> > Hello all,
> >
> > I'm having a problem with IPAddr, and I'm hoping someone can
> > explain it to
> > me.  I've done the following test, and I get the results shown below.
> >
> > irb(main):001:0> require 'ipaddr'
> > => true
> > irb(main):002:0> net_1 = IPAddr.new("192.168.0.0/16")
> > => #<IPAddr: IPv4:192.168.0.0/255.255.0.0>
> > irb(main):003:0> net_2 = IPAddr.new("192.168.0.0/24")
> > => #<IPAddr: IPv4:192.168.0.0/255.255.255.0>
> > irb(main):004:0> net_1.include?(net_2)
> > => true
> > irb(main):005:0> net_2.include?(net_1)
> > => true
> > irb(main):006:0>
>
> It is because include? is treating its argument as an address not as
> a network.  The subnet mask of the argument is ignored.  So
> net_2.include?(net_1) is really asking whether the first address of
> net_1 (192.168.0.0) is contained in net_2 and that is true.
>
> Gary Wright
>
>
>

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