What is the origin of the private network address 192.168.*.*? (2009)
84 comments
·September 7, 2025isThereClarity
JdeBP
And said the same on SuperUser the day after.
notepad0x90
And I suppose 127/8 because it's the highest /7 or highest /8 without the MSB on?
null
3np
The entire thread:
>>> This is a fuzzy recollection of something I believe I read, which might well be inaccurate, and for which I can find no corroboration. I mention it solely because it might spark memories from someone who actually knows:
>>> A company used 192.168.x.x example addresses in some early documentation. A number of people followed the manual literally when setting up their internal networks. As a result, it was already being used on a rather large number of private networks anyway, so it was selected when the RFC 1597 was adopted.
>> sun
> Wasn't 192.9.200.x Sun's example network?
of course you are correct. sorry. jet lag and not enough coffee.
---
So no answers.
nickdothutton
I worked in the early 90s getting UK companies connected. The number of people who had copied Suns (and HPs and others) addresses out of the docs was enormous. One of them was a very well known token ring network card vendor.
pumplekin
You should read https://datatracker.ietf.org/doc/html/rfc1627 for a path not travelled.
Not everyone thought this was a good idea, and I still maintain the alternative path would have led to a better internet than the one we today.
zokier
As the authors themselves note, RFC 1597 was merely formalizing already widespread common practice. If the private ranges were not standardized then people would still have created private networks, but just used some random squatted blocks. I can not see that being better outcome.
wongarsu
The optimist in me wants to claim that not assigning any range for local networks would have lead to us running out of IPv4 addresses in the late 90s, leading to the rapid adoption of IPv6, along with some minor benefits (merging two private networks would be trivial, much fewer NATs in the world leading to better IP based security and P2P connectivity).
The realists in me expects that everyone would have used one of the ~13 /8 blocks assigned to the DoD
jvanderbot
The realist in me thinks that we'd probably have had earlier adoption of V6 but the net good from that is nil compared to the headaches.
V6 is only good when V4 is exhausted, so it's tautological to call it a benefit of earlier exhaustion of V4, or am I missing something? I'm probably missing something.
high_priest
Can you please elaborate? How would such a minute change lead to "a better internet"?
emacsen
I'm not the OP or author, but the argument against private network addresses is that such addresses break the Internet in some fundamental ways. Before I elaborate on the argument, I want to say that I have mixed feelings on the topic myself.
Let's start with a simple assertion: Every computer on the Internet has an Internet address.
If it has an Internet Address, it should be able to send packets to any computer on the Internet, and any other computer on the Internet should be able to send packets to it.
Private networks break this assumption. Now we have machines which can send packets out, but can't receive packets, not without either making firewall rule exceptions or else doing other firewall tricks to try to make it work. Even then, about 10-25% of the time, it doesn't work.
But it goes beyond firewall rules... with IP addresses being tied to a device, every ISP would be giving every customer a block of addresses, both commercial and residential customers.
We'd also have seen fast adoption of IPv6 when IPv4 ran out. Instead we seem to be stuck in perpetual limbo.
On team anti-private networking addresses:
- Worse service from ISPs - IPv4 still in use past when it should have been replaced - Complex work around overcoming firewalls
I'm sure we all know the benefits of private networks, so I don't need to reiterate it.
ipdashc
> But it goes beyond firewall rules
Honestly though... does it, all that much? Even in a world where NAT didn't exist and we all switched to IPv6, we'd still all be behind firewalls, as everyone on an IPv6 home network is today. Port forwarding would just be replaced by firewall exemptions.
Like on a philosophical level, I do wish we had a world where the end-to-end principle still held and all that, but I'm not actually sure what difference it would make, practically speaking. "Every device is reachable" didn't die because of IPv4 exhaustion or NAT, it died because of security, in reality most people don't actually want their devices to be reachable (by anyone).
mrheosuper
> Every computer on the Internet has an Internet address
By every computer did you include every MCU that can run TCP/IP stack ?
tzs
> I'm sure we all know the benefits of private networks, so I don't need to reiterate it
That is I think the key. Private networks have sufficient benefit that most places will need one.
The computers and devices on our private network will fall into 3 groups: (1) those that should only communicate within our private network, (2) those that sometimes need to initiate communication with something outside our network but should otherwise have no outside contact, and (3) those that need to respond to communication initiated from something outside our network.
We could run our private network on something other than IP, but then dealing with cases #2 and #3 is likely going to be at least as complicated as the current private IP range approach.
We could use IP but not have private ranges. If we have actual assigned addresses that work from the outside for each device we are then going to have to do something at the router/firewall to keep unwanted outside traffic from reaching the #1 and #2 types of devices.
If we use IP but do not have assigned addresses for each device and did not have the private ranges I'd expect most places would just use someone else's assigned addresses, and use router/firewall rules to block them off from the outside. Most places can probably find someone else's IP range that they are sure contains nothing they will ever need to reach so should be safe to use (e.g., North Korea's ranges would probably work for most US companies). That covers #1, but for #2 and #3 we are going to need NAT.
I think nearly everyone would go for IP over using something other than IP. Nobody misses the days when the printer you wanted to buy only spoke AppleTalk and you were using DECnet.
At some point, when we are in the world where IP is what we have on both the internet and our private networks but we do not have IP ranges reserved for private networks, someone will notice that this would be a lot simpler if we did have such ranges. Routers can then default to blocking those ranges and using NAT to allow outgoing connections. Upstream routers can drop those ranges so even if we misconfigure ours it won't cause problems outside. Home routers can default to one of the private ranges so non-tech people trying to set up a simple home network don't have to deal with all this.
If for some reason IANA didn't step in and assign such ranges my guess is that ISPs would. They would take some range within their allocation, configure their routers to drop traffic using those address, and tell customers to use those on their private networks.
zokier
> every ISP would be giving every customer a block of addresses, both commercial and residential customers.
or more likely, you would still receive only handful of addresses and would have needed to be far more considerate what you connect to your network, thus restricting the use of IP significantly. Stuff like IPX and AppleNet etc would have probably then been more popular. The situation might have been more like what we had with POTS phones; residential houses generally had only one phone number for the whole house and you just had to share the line between all the family members etc.
dang
Related. Others?
What's the history behind 192.168.1.1? - https://news.ycombinator.com/item?id=17467203 - July 2018 (48 comments)
zettabomb
Weirdly enough, there are a few systems at my workplace which are in the 192.9.200.x subnet! They're only about 20 years old, though. We are actively looking to replace the entire system.
Aeolun
From another post on here:
> > Wasn't 192.9.200.x Sun's example network?
> of course you are correct. sorry. jet lag and not enough coffee.
EvanAnderson
I've done work for several municipalities and police departments in western Ohio and found 192.9.200.0/24 in several. They all had a common vendor who did work back in the 90s and was the source.
Hilift
Most SMB companies did not have IP addresses in 1994 when RFC 1597 was published, although the range was known. However, the well known companies did, and some of those have the older full class B assignments. It was common for those companies to use those public IP addresses internally to this day, although RFC-1918 addresses were also in use.
Since Netware was very popular in businesses and it was possible/common to use only the IPX protocol for endpoints, you could configure endpoints to use a host that had both an IPX and IP address as the proxy, and not use an IP address on most endpoints. That was common due to Netware actually charged for DHCP and DNS add-ons. When Windows became more popular, IP on endpoints likely used RFC-1918 around ~1996.
B1FF_PSUVM
> It was common for those companies to use those public IP addresses internally to this day
Yep, a desktop PC with its own IPv4 address. Back in the day, no firewall afaik.
simne
Well, I'll try summarize answers and my experience.
At beginning, Internet used network classes, because of hardware limitations (later switched to address blocks). And even in 1990s still existed very old hardware, only could use class addresses.
What classes mean, existed early very large organizations, got more addresses than they could use. And even happen few cases, when such organizations lost rights for these addresses.
And these unlucky organizations was some big whales, like IBM or ATT/Bell or Sun.
And once invented solution - state some big enough network as not allocated to use under NAT (or when network is not connected to Internet). So, departments of big organizations could use TCP/IP stack in their networks, even with old hardware, but don't need to contact Internet officials to got real internet addresses.
192.168 was just first C-class network prefix, was not assigned at the moment (or just released).
Later, to list of unassigned added 172.16/12 network.
merlyn
Note, the CIDR RFC didn't come out until Sep 1993. Thus even brand new network equipment in the mid 1990's were still very classful. And even then, knowledge of how to properly use /etc/netmasks in SunOS v4.x (or the equivalent if some other network stack even had one) was very scarce.
In the mid 90's, SMBs connecting to the Internet would have very typically obtained a /24 from their ISP, and had direct connection online, no firewalls, barely any proxy servers (although that was popular for some mid sized customers that would have needed multiple /24s or even a /16 to get all their workstations online).
It wasn't until the company Network Translation, with the PIX came about that anybody even considered doing private IP address in general as a firewall strategy with NAT translation using private IPs. And then it took years and years to become popular. Long bought by Cisco at that point.
I don't think Cisco IOS even had NAT until something like 10.2, when it was a premium license package.
michaelcampbell
This is probably apocryphal, and I'm probably getting the details wrong anyway, but tangentially related to this, when I worked for a small network security firm (later purchased by Cisco, as most were), we had a customer that used, I'm told, the IP ranges typically seen in North Korea as their internal network. They TOLD us they did it because the addresses wouldn't conflict with anything they cared about, and no one had told them about 1918 + NAT, which I find dubious.
This was in the 10's of 1000's of devices.
dreamcompiler
Apparently this is an example of paving the cowpath.
weinzierl
Since the posting does not give a real answer.
192 is 11000000 in binary.
So it is simply the block with the first two bits set in the netmask.
168 is a bit more difficult. It is 10101000, a nice pattern but I don't know why this specific pattern.
marcusb
I don't think this does anything to explain why 192.168/16 was chosen specifically. Three netblocks (10/8, 172.16/12, and 192.168/16) were selected from the class A, B, and C address spaces to accommodate private networks of various sizes. Class C addresses by definition have the two most significant bits set in their first octet and the third set to 0 (i.e., 192 - 223.)
192 in the first octet starts the class C space, but 10 and 172 do not have the same relationship in classes A and B.
weinzierl
Yes you are right. I researched a bit and there are other reserved blocks next the 168 that obviously don't have a nice pattern. So the 101010 is just a coincidence.
drewolbrich
101010 in decimal is 42.
Hikikomori
192 is the first C class, 168 likely next available when rfc1918 was written.
weinzierl
This is the most likely thing that happened.
tmn007
This is a bit of history in https://www.rfc-editor.org/rfc/rfc1466
kragen
Is it? What section do you mean? I don't see anything in there about private networks or 192.168.0.0/16 (in CIDR notation, which didn't exist at the time).
Sharlin
User bmacho cites this Superuser question [1] in a reply to a downvoted comment at the bottom of this thread. It’s much more illuminating than the OP emails; Michael Hampton’s answer in particular is amazing. I had never heard of Jon Postel before.
[1] https://superuser.com/questions/784978/why-did-the-ietf-spec...
morning-coffee
> I had never heard of Jon Postel before.
Reading this makes me a bit sad and reminds me that I'm older now and lucky to have grown up during the golden age of the Internet.
Sharlin
Mm. I’m an older millennial, so solidly in the Web 1.0 generation, but never had the chance to use the internet before the web took off. I missed BBSs too, which were big where I’m from (probably bigger than the pre-Web internet, outside universities at least). I was fourteen when Postel died in 1998. My earliest memories of internet use are probably from ’96 or so, using library or school computers after classes.
Daniel Karrenberg, co-author of RFC1918, said this 2017-10-06 on the NANOG mailing list:
https://web.archive.org/web/20190308152212/https://mailman.n...