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100.64.0.0/10 is a reserved IP block for carrier-grade NAT.

by yegle 2y ago

metadat 2y ago
More info about Carrier-Grade NAT (for others who, like me, are only encountering this term for the time): https://en.wikipedia.org/wiki/Carrier-grade_NAT https://en.wikipedia.org/wiki/Carrier-grade_NAT Can anyone elighten me regarding what is different or special about 100.64.0.0/10 vs say, 192.168.0.0 or 10.0.0.0. Edit: Answered my own question by digging into more wikis, there is a helpful table of reservations and intentions here: https://en.wikipedia.org/wiki/Reserved_IP_addresses https://en.wikipedia.org/wiki/Reserved_IP_addresses
- throw0101d 2y ago
  > Can anyone elighten me regarding what is different or special about 100.64.0.0/10 vs say, 192.168.0.0 or 10.0.0.0. A bit of context: if an ISP cannot get enough IPv4 addresses for the WAN-side of people's home routers, some problems exist: * something in 192.168/16 is generally used for the LAN-side of people's home routers, so that cannot be used on the WAN side * 10/8 is used for business/enterprise corporate networks, so it also cannot be used on the WAN side because if people VPN connect to the corporate, then the router may get confused * similarly for 172.12/12: often used for corporate networks So the IETF/IANA set aside 100.64.0.0/10 as it had no 'legacy' of use anywhere else, and is specifically called out to only be used for ISPs for CG-NAT purposes. This way its routing does not clash with any other use (home or corporate/business). IPv4 address space is nearly exhausted. However, ISPs must continue to support IPv4 growth until IPv6 is fully deployed. To that end, many ISPs will deploy a Carrier-Grade NAT (CGN) device, such as that described in [RFC6264]. Because CGNs are used on networks where public address space is expected, and currently available private address space causes operational issues when used in this context, ISPs require a new IPv4 /10 address block. This address block will be called the "Shared Address Space" and will be used to number the interfaces that connect CGN devices to Customer Premises Equipment (CPE). * https://www.rfc-editor.org/rfc/rfc6598.html https://www.rfc-editor.org/rfc/rfc6598.html
  - metadat 2y ago
    Interesting, I thought docker uses 172.*.
    - deleted 2y ago
      [deleted]
    - yjftsjthsd-h 2y ago
      It does; 172.16.0.0/12 is just another RFC1918 internal subnet. Edit: I should say, a subnet that docker carves smaller subnets out of for its networks.
    - throw0101d 2y ago
      Yes, 172.18/16 by default. And that actually was a problem at a previous job I was at: when COVID hit our VPN address range just happened to be set to be in that range, and so a bunch of developers were having issues. (IIRC, we re-configured the VPN appliance to use something else.)
    - 9dev 2y ago
      …and it’s a perfect display of the technical competence of Docker Inc. :) they do stuff like that, in all kinds of domains, all the time.

100.64.0.0/10 is a reserved IP block for carrier-grade NAT.

by yegle 2y ago

100.64.0.0/10 is a reserved IP block for carrier-grade NAT.

More info about Carrier-Grade NAT (for others who, like me, are only encountering this term for the time): https://en.wikipedia.org/wiki/Carrier-grade_NAT https://en.wikipedia.org/wiki/Carrier-grade_NAT Can anyone elighten me regarding what is different or special about 100.64.0.0/10 vs say, 192.168.0.0 or 10.0.0.0. Edit: Answered my own question by digging into more wikis, there is a helpful table of reservations and intentions here: https://en.wikipedia.org/wiki/Reserved_IP_addresses https://en.wikipedia.org/wiki/Reserved_IP_addresses

throw0101d 2y ago
> Can anyone elighten me regarding what is different or special about 100.64.0.0/10 vs say, 192.168.0.0 or 10.0.0.0. A bit of context: if an ISP cannot get enough IPv4 addresses for the WAN-side of people's home routers, some problems exist: * something in 192.168/16 is generally used for the LAN-side of people's home routers, so that cannot be used on the WAN side * 10/8 is used for business/enterprise corporate networks, so it also cannot be used on the WAN side because if people VPN connect to the corporate, then the router may get confused * similarly for 172.12/12: often used for corporate networks So the IETF/IANA set aside 100.64.0.0/10 as it had no 'legacy' of use anywhere else, and is specifically called out to only be used for ISPs for CG-NAT purposes. This way its routing does not clash with any other use (home or corporate/business). IPv4 address space is nearly exhausted. However, ISPs must continue to support IPv4 growth until IPv6 is fully deployed. To that end, many ISPs will deploy a Carrier-Grade NAT (CGN) device, such as that described in [RFC6264]. Because CGNs are used on networks where public address space is expected, and currently available private address space causes operational issues when used in this context, ISPs require a new IPv4 /10 address block. This address block will be called the "Shared Address Space" and will be used to number the interfaces that connect CGN devices to Customer Premises Equipment (CPE). * https://www.rfc-editor.org/rfc/rfc6598.html https://www.rfc-editor.org/rfc/rfc6598.html
- metadat 2y ago
  Interesting, I thought docker uses 172.*.
  - deleted 2y ago
    [deleted]
  - yjftsjthsd-h 2y ago
    It does; 172.16.0.0/12 is just another RFC1918 internal subnet. Edit: I should say, a subnet that docker carves smaller subnets out of for its networks.
  - throw0101d 2y ago
    Yes, 172.18/16 by default. And that actually was a problem at a previous job I was at: when COVID hit our VPN address range just happened to be set to be in that range, and so a bunch of developers were having issues. (IIRC, we re-configured the VPN appliance to use something else.)
  - 9dev 2y ago
    …and it’s a perfect display of the technical competence of Docker Inc. :) they do stuff like that, in all kinds of domains, all the time.