Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium


Using unassigned public ip addresses on a private network

Posted on 2008-11-14
Medium Priority
Last Modified: 2013-11-29
I recently came across a client who is using public ip addresses on their LAN and WAN. These ip addresses have not been assigned to them. I suppose they have been able to do this because they are NATed. My question is: isnt this illegal? and what are the real and implied technical implications of such a setup.
Question by:exagger
  • 2
  • 2

Accepted Solution

cluebeck earned 100 total points
ID: 22958728
i would not say its illegal. the implication for this scenario would be, that your client will not be able to communicate with whoevers ip-adresses he is using. (since the router will send the packets within the own subnet)
Other then that i don't see any problems.
LVL 10

Assisted Solution

Kieran_Burns earned 100 total points
ID: 22958758
We have a client doing the exact same thing.
We are also in the middle of undoing this allocation of IP addresses! As above - the REAL world IP address (range) will not be contactable as the internal routing will point all requests to the internal devices.
As long as these IP addresses do not appear on the 'net then there is no problem. If they start to do so then there are legal implications.
I'm really just enforcing what is said first - but having seen it in action (and it has been for some years) I can categorically state that there are no 'real' implications beyond stuffed routing if the IP addresses do become allocated. Our clients actually ARE! (but not for a domain that they would ever need to contact)

Author Comment

ID: 22958781
Well this actually block is actually already assigned. Its actually a whole /16.

I havent had a chance to meet the person who came up with this particular clients address scheme, but Im curious to know, from your experience, with all the flexibility of private ip address why would anyone want a setup like this?
LVL 10

Expert Comment

ID: 22958813
I'm not sure we're allowed to clearly express our opinion of individuals who do that on this forum ;-)
A 16-bit public allocation? Wow. In which case there are 65000 ip addresses he can't see on the 'tinterweb. That's going to hurt, and I expect that there will be odd 'issues' popping up when people browse.
One solution I suppose would be to use a proxy server that has an EXTERNAL DNS Server entry only (can't resolve internal IP addresses) and direct all web browsing traffic to it. Make sure it NATs all through traffic and at least that issue will be sorted.
In the meantime, cost up a project to reallocate IP addresses ;-)

Author Comment

ID: 22958851
Not an opinion of the individual but the situations in which anyone would choose to design their network in this way.

Featured Post

Hire Technology Freelancers with Gigs

Work with freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely, and get projects done right.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I wrote this article to explain some important DNS concepts that should be known to avoid some typical configuration errors I often see in forums. I assume that what is described here is the typical behavior of Microsoft DNS client. I don't know …
BIND is the most widely used Name Server. A Name Server is the one that translates a site name to it's IP address. There is a new bug in BIND (https://kb.isc.org/article/AA-01272), affecting all versions of BIND 9 from BIND 9.1.0 (inclusive) thro…
Viewers will learn how to properly install and use Secure Shell (SSH) to work on projects or homework remotely. Download Secure Shell: Follow basic installation instructions: Open Secure Shell and use "Quick Connect" to enter credentials includi…
In this brief tutorial Pawel from AdRem Software explains how you can quickly find out which services are running on your network, or what are the IP addresses of servers responsible for each service. Software used is freeware NetCrunch Tools (https…
Suggested Courses
Course of the Month14 days, 13 hours left to enroll

578 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question