non-private IPv4 addresses in LAN

[Justinh]

My company (very large, global) has been using a 134.x.x.x address range for intranet devices for like 15 years. (It just recently went to 10.x.x.x, so it made me think about this some more.)
How can a non-private address range be used in the LAN?

 

[ColinTaylor]

Well, just because you shouldn't disregard the agreed standards doesn't mean you can't. This is assuming that you don't actually own the 134.x.x.x address range, and want LAN devices to be directly accessible from the internet. At the end of the day there's nothing stopping you using whatever address range you want.

 

[tgl]

The thing that should stop you is that if you ever try to access external servers that legitimately live in 134.x.x.x, your network will misbehave and send you to local addresses instead. Of course, maybe that's what you want ... but it's the sort of thing that will bite you on the rear at unexpected times.

 

[Tech9]

servers that legitimately live in 134.x.x.x

This very large global company may be legitimately using this IP range.

 

[tgl]

Well, the question was quite vaguely worded ... but what I took it to mean is "what will happen if I just commandeer some public IP address range for my private network?"

 

[RMerlin]

My company (very large, global) has been using a 134.x.x.x address range for intranet devices for like 15 years. (It just recently went to 10.x.x.x, so it made me think about this some more.)
How can a non-private address range be used in the LAN?

This is how it used to work, NAT wasn't always a thing.

That's why in the early days, so many corporations jumped to grab a whole /8 even tho they definitely weren't going to run 16 millions servers within their business.

I've encountered one customer myself who used to do that. Me and our engineer were analyzing their network (a potential new customer at the time). Their rationale as to why it was this way? "We need that to provide remote access to some of our computers".

Yeaaahhhhh...

The scariest part is that potential customer was a governmental-related organisation.

 

[tgl]

Yeah, RFC1918 and the widespread adoption of NAT changed the landscape completely. Without that, IPv4 would've stopped being relevant at all years ago.

 

[Tech9]

but what I took it to mean is "what will happen if I just commandeer some public IP address range for my private network?"

I've read @Justinh question instead. It was pretty clear. The very large global company for sure owns some of the 134.x.x.x range, it's their decision how to use it and the answer is - the configuration is valid.

 

[Justinh]

Got some history on this ... The company did buy that public space. With all the company acquisitions, they found it easier to use this non-private range (re-IP, it was called) to avoid conflicts with the other existing private network ranges instead of using NAT. Also it kept the load down on the firewalls, I'm told.

Appreciate the inputs.

 

[sfx2000]

My company (very large, global) has been using a 134.x.x.x address range for intranet devices for like 15 years. (It just recently went to 10.x.x.x, so it made me think about this some more.)
How can a non-private address range be used in the LAN?

Nothing unusual - if they have the public address space, they can use it however they want - when I joined a large tech company back in '95, all devices had addresses that were publicly routable... having a /16 allows for a lot of IPv4 addresses when one is a Small to Medium Enterprise (they were eventually an S&P500 and NASDAQ listed company)...

They did eventually move over to NAT for IPv4, much like your company with the 10dot's...

Most home networks use NAT - some of it is to conserve IPv4 addresses, but one has to question when the ISP hands out a /24 for a residential/home network... technically I can disable NAT, and assign IP's in the range they've given me with the /24...

 

[sfx2000]

The scariest part is that potential customer was a governmental-related organisation.

Looking back about 6 years ago - the US Department of Defense released a number of /8's to ARIN - about 175 million addresses in total that were reserved way back in the day when the Internet was first getting set up...

There's a lot of other companies that received /8's back in the day, and are now selling off blocks for good money...

Ukraine is doing similar for their blocks of IPv4 to raise funds - likely they may be the first IPv6 only country with a small block of IPv4's for things like CGNAT...