Skip private networks #49
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`devp2p` did not discriminate "private" and public network addresses. This can lead to at least the following issues: 1) If peers (incorrectly) reports a private network address as endpoint, this fills the discovery with a lot of incorrect entries. 2) On the other hand is it hard to keep nodes in a private network protected from discovery requests from the outside. With this change, each Address from devp2p will be checked against a range of "allowed networks", which consists of a whitelist (default empty) and a blacklist (default populated with most entries from `ipaddress._IPv4Constants._private_networks`). Entries to the whitelist take precedence over the blacklist. User libraries can adjust the behaviour via environment variables or changing the instance `devp2p.discovery.ALLOWED_NETWORKS`.
In tests we need to enable local networks in the discovery module.
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PR opened for discussion
ping @fjl @heikoheiko
please fill in other interested parties!
Description
devp2pdid not discriminate "private" and "public" network addresses.This can lead to at least the following issues:
If peers (incorrectly) report a "private" network addresses as endpoints,
this fills the discovery with a lot of incorrect entries.
see also: https://www.reddit.com/r/ethereum/comments/55xjrb/yet_another_new_attack_using_faked_ip_src/
On the other hand is it hard to keep nodes in a private network protected
from discovery requests from the outside.
With this change, each
Addressfrom devp2p will be checked against a range of"allowed networks", which consists of a whitelist (default empty) and a blacklist
(default populated with most entries from
ipaddress._IPv4Constants._private_networks).If a new
Addressis not in the "allowed" list, it will invalidate with aValueError.Entries to the whitelist take precedence over the blacklist. User libraries
can adjust the behaviour via environment variables or changing the instance
devp2p.discovery.ALLOWED_NETWORKS.