[ale] 5.x.x.x IP range

Michael B. Trausch mbt at naunetcorp.com
Fri Dec 13 17:54:54 EST 2013


On 12/13/2013 02:31 PM, Edward Holcroft wrote:
> What is 5.x.x.x? I've never heard of them before and am I allowed to
> use them? More importantly, where are they coming from? I never set
> anything to offer IP's in that range, unless it's some kind of default.

The whois utility can tell you a good bit:

  * 5.0.0.0/8 is *allocated* for assignment by RIPE, meaning that these
    addresses belong in Europe.
  * Various chunks of it are assigned to ISPs and backbone links (e.g.
    5.0.0.0/17).

This means that you should absolutely not be using these IP addresses,
as they /will/ conflict with the public Internet.

Verify that the configuration of the server handing out the addresses is
correct; even Microsoft products should not intentionally be using IP
address space that is not allocated to it, unless some administrator in
the admin chain told it to figuring that it wouldn't hurt anything.

Remember the private IPv4 networks:

 1. 10.0.0.0/8 if you need something very large.
 2. 172.16.0.0/12 if you need something moderately large and nonconflicting.
 3. 192.168.0.0/16 if you need something recognizable.  I don't use this
    range anymore, myself.

I also use the TEST-NET-1 through TEST-NET-3 allocations for LAN-only
testing of development apps and systems, but I never deploy anything
with those addresses.

For dial-in and VPN access, you should be using either addresses
assigned to you by your upstream (e.g., your ISP or ARIN), RFC1918 space
(one of the three ranges listed above), or assigned, delegated or
organization-local IPv6 addressing.

Ideally, the VPN should be its own routed subnet.  This isn't always
possible though, so many VPN servers will actually do proxy-ARP to make
the VPN-connected peers appear to be on the local subnetwork.

    --- Mike

-- 
Naunet Corporation Logo 	Michael B. Trausch

President, *Naunet Corporation*
? (678) 287-0693 x130 or (855) NAUNET-1 x130
FAX: (678) 783-7843

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