Groups > comp.os.linux.networking > #1606

Re: Dealing with a network knowledge troll!

From	telsar <noone@nowhere.com>
Newsgroups	comp.os.linux.networking
Subject	Re: Dealing with a network knowledge troll!
Date	2012-08-24 12:09 -0500
Organization	none
Message-ID	<k18chb$9dp$1@dont-email.me> (permalink)
References	<slrnk3drvp.1eu.dev.null@usenet.home.b0h0.com>

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On 8/23/2012 10:07 PM, Mike Lovell wrote:
> Hello,
> 
> I've got a guy who claims these:
> 
> 	10.255.255.81/24
> 	192.168.255.81/24
> 
> Are invalid unicast IP's, because any IP with a "255" in it *anywhere*
> is reserved for being a broadcast IP.
> 
> To which he cites:
> http://www.comptechdoc.org/independent/networking/guide/netaddressing.html
> 
> 
> Now I immediately know this is wrong because you can use a "0" or "255"
> on the end of a host IP:
> http://en.wikipedia.org/wiki/IPv4#Addresses_ending_in_0_or_255
> 
> 
> And of course the RFC says it's fine to use a "255" in the 1st to 3rd
> octets.  Nothing about this is reserved or makes the address
> specifically a broadcast one.
> 
> 
> And you can even find reachable hosts out there with "255" in them:
> 
> 
> host ns2.televork.ee
> ns2.televork.ee has address 81.21.255.1
> 
> host www.lepton-line.jp
> www.lepton-line.jp has address 121.83.255.1
> 
> 
> So every router between me and them (for me to reach them) would have to
> be broken it allow this, if the other guy is right about them being
> invalid!
> 
> 
> 
> Question:
> 
> Am I correct (the IP's are valid) or is he (the IP's are invalid)?  And why?
> 
> 

Well, it may say its valid for use and all, and a lot depends on the
mask used.  But, it would be an odd thing to do as most avoid this
value.  Using it may find some bugs scattered around in software.
Arguing about specs like this is a bit silly, anyway.  Its IPv6 time,
lots of room for adventure especially concerning the conversion from
IPv4.  Should have some dazzling times ahead.

PS:  Anyone seeing a "255" would think its some kind of broadcast
thingy, except us.
- -- 
Steal a little and go to jail, steal a lot and become King.
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Thread

Dealing with a network knowledge troll! Mike Lovell <dev.null@b0h0.com> - 2012-08-23 22:07 -0500
  Re: Dealing with a network knowledge troll! David Brown <david@westcontrol.removethisbit.com> - 2012-08-24 09:05 +0200
  Re: Dealing with a network knowledge troll! Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-08-24 07:17 +0000
    Re: Dealing with a network knowledge troll! Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2012-08-24 10:29 -0500
    Re: Dealing with a network knowledge troll! Mike Lovell <dev.null@b0h0.com> - 2012-08-24 10:53 -0500
      Re: Dealing with a network knowledge troll! "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2012-08-24 14:02 -0400
      Re: Dealing with a network knowledge troll! Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-08-24 20:21 +0000
  Re: Dealing with a network knowledge troll! Richard Kettlewell <rjk@greenend.org.uk> - 2012-08-24 09:07 +0100
  Re: Dealing with a network knowledge troll! telsar <noone@nowhere.com> - 2012-08-24 12:09 -0500
    Re: Dealing with a network knowledge troll! Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2012-08-24 14:29 -0500
      Re: Dealing with a network knowledge troll! telsar <noone@nowhere.com> - 2012-08-24 15:58 -0500
        Re: Dealing with a network knowledge troll! Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-08-24 22:23 +0000
          Re: Dealing with a network knowledge troll! telsar <noone@nowhere.com> - 2012-08-25 12:40 -0500
    Re: Dealing with a network knowledge troll! Richard Kettlewell <rjk@greenend.org.uk> - 2012-08-25 09:38 +0100
      Re: Dealing with a network knowledge troll! telsar <noone@nowhere.com> - 2012-08-25 12:35 -0500

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