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What if the my network uses several different local subnets? How would the browser figure that out? No, blocking all these IP ranges is a good idea. After all,

by pferde 6y ago

What if the my network uses several different local subnets? How would the browser figure that out? No, blocking all these IP ranges is a good idea. After all, these ranges are supposed to not be directly routeable to from the Internet.

tzs 6y ago
> What if the my network uses several different local subnets? How would the browser figure that out? It would look at your computer's routing table. If it is an IP address your computer talks to directly, it is on a LAN your computer is on and would be blocked. If it is an IP address that your computer talks to through a gateway, it is on the internet and would not be blocked. > After all, these ranges are supposed to not be directly routeable to from the Internet. They are supposed to not be directly routeable to/from the public internet. They can be directly routable between non-public parts of the internet. A not uncommon example, especially now, is having a VPN connection between a home network and the internal network of a business, both of which are using addresses in the private ranges.
- pdonis 6y ago
  > If it is an IP address that your computer talks to through a gateway, it is on the internet and would not be blocked. No, this would just make the security problem worse, because now any website could use websockets to scan, not just your personal LAN, but any network you are connected to through a VPN or any other gateway.
- pferde 6y ago
  > They are supposed to not be directly routeable to/from the public internet. They can be directly routable between non-public parts of the internet. Sure, but this is different from a VPN. This would be untrusted code downloaded from a remote website talking to unrelated devices on my local network. Effectively, it would be the remote website having free reign inside my local network, with my web browser acting as a proxy (or as a trojan horse, with a bit of exaggeration).

by pferde 6y ago

tzs 6y ago

> What if the my network uses several different local subnets? How would the browser figure that out? It would look at your computer's routing table. If it is an IP address your computer talks to directly, it is on a LAN your computer is on and would be blocked. If it is an IP address that your computer talks to through a gateway, it is on the internet and would not be blocked. > After all, these ranges are supposed to not be directly routeable to from the Internet. They are supposed to not be directly routeable to/from the public internet. They can be directly routable between non-public parts of the internet. A not uncommon example, especially now, is having a VPN connection between a home network and the internal network of a business, both of which are using addresses in the private ranges.

pdonis 6y ago
> If it is an IP address that your computer talks to through a gateway, it is on the internet and would not be blocked. No, this would just make the security problem worse, because now any website could use websockets to scan, not just your personal LAN, but any network you are connected to through a VPN or any other gateway.
pferde 6y ago
> They are supposed to not be directly routeable to/from the public internet. They can be directly routable between non-public parts of the internet. Sure, but this is different from a VPN. This would be untrusted code downloaded from a remote website talking to unrelated devices on my local network. Effectively, it would be the remote website having free reign inside my local network, with my web browser acting as a proxy (or as a trojan horse, with a bit of exaggeration).