I was doing some work on AWS and wanted to know what IP addresses were being used. Luckily for me, AWS publishes this all here https://ip-ranges.amazonaws.com/ip-ranges.json. When you go through this list, you’ll quickly see that AWS has a massive asset of IPv4 allocations. Just counting quickly I noticed a lot of big prefixes.
However, the IPv4 ranges on that list are just the ranges that are in use and allocated today by AWS. Time to dig a bit deeper.
IPv4 address acquisitions by AWS
Over the years, AWS has acquired a lot of IPv4 address space. Most of this happens without gaining too much attention, but there were a few notable acquisitions that I’ll quickly summarize below.
2017: MIT selling 8 million IPv4 addresses to AWS
In 2017 MIT sold half of its 18.0.0.0/8 allocation to AWS. This 18.128.0.0/9 range holds about 8 million IPv4 addresses.
2018: GE sells 3.0.0.0/8 to AWS
In 2018 the IPv4 prefix 3.0.0.0/8 was transferred from GE to AWS. With this, AWS became the proud owner of its first /8! That’s sixteen million new IPv4 addresses to feed us hungry AWS customers. https://news.ycombinator.com/item?id=18407173
2019: AWS buys AMPRnet 44.192.0.0/10
In 2019 AWS bought a /10 from AMPR.org, the Amateur Radio Digital Communications (ARDC). The IPv4 range 44.0.0.0/8 was an allocation made to the Amateur Radio organization in 1981 and known as the AMPRNet. This sell caused a fair bit of discussion, check out the nanog discussion here.
Just this month, it became public knowledge AWS paid $108 million for this /10. That’s $25.74 per IP address.
These are just a few examples. Obviously, AWS has way more IP addresses than the three examples I listed here. The IPv4 transfer market is very active. Check out this website to get a sense of all transfers: https://account.arin.net/public/transfer-log
All AWS IPv4 addresses
Armed with the information above it was clear that not all of the AWS owned ranges were in the JSON that AWS published. For example, parts of the 3.0.0.0/8 range are missing. Likely because some of it is reserved for future use.
I did a bit of digging and tried to figure out how many IPv4 addresses AWS really owns. A good start is the Json that AWS publishes. I then combined that with all the ARIN, APNIC, and RIPE entries for Amazon I could find. A few examples include:
https://rdap.arin.net/registry/entity/AMAZON-4
https://rdap.arin.net/registry/entity/AMAZO-4
https://rdap.arin.net/registry/entity/AT-88-Z
Combining all those IPv4 prefixes, removing duplicates and overlaps by aggregating them results in the following list of unique IPv4 address owned by AWS: https://gist.github.com/atoonk/b749305012ae5b86bacba9b01160df9f#all-prefixes
The total number of IPv4 addresses in that list is just over 100 Million (100,750,168). That’s the equivalent of just over six /8’s, not bad!
