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Add check for CGNAT IP range when checking for private IPs #4975

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Merged
y9v merged 1 commit into from
Oct 15, 2025
Merged

Add check for CGNAT IP range when checking for private IPs #4975

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4 changes: 3 additions & 1 deletion lib/datadog/core/utils/network.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ module Network
cf-connecting-ipv6
].freeze

CGNAT_IP_RANGE = IPAddr.new('100.64.0.0/10')

class << self
# Returns a client IP associated with the request if it was
# retrieved successfully.
Expand Down Expand Up @@ -131,7 +133,7 @@ def strip_ipv4_port(ip)
end

def global_ip?(parsed_ip)
parsed_ip && !parsed_ip.private? && !parsed_ip.loopback? && !parsed_ip.link_local?
parsed_ip && !parsed_ip.private? && !parsed_ip.loopback? && !parsed_ip.link_local? && !CGNAT_IP_RANGE.include?(parsed_ip)
end
end
end
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2 changes: 2 additions & 0 deletions sig/datadog/core/utils/network.rbs
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Expand Up @@ -4,6 +4,8 @@ module Datadog
module Network
DEFAULT_IP_HEADERS_NAMES: ::Array[::String]

CGNAT_IP_RANGE: ::IPAddr

def self.stripped_ip_from_request_headers: (Datadog::Core::HeaderCollection headers, ?::Array[::String] ip_headers_to_check) -> ::String?
def self.stripped_ip: (::String ip) -> String?

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7 changes: 7 additions & 0 deletions spec/datadog/core/utils/network_spec.rb
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Expand Up @@ -25,6 +25,13 @@
result = described_class.stripped_ip_from_request_headers(headers)
expect(result).to eq('43.43.43.43')
end

it 'does not return IPs from carrier-grade NAT IP range' do
headers = Datadog::Core::HeaderCollection.from_hash({'X-Forwarded-For' => '100.64.0.105,43.43.43.43,fe80::1'})

result = described_class.stripped_ip_from_request_headers(headers)
expect(result).to eq('43.43.43.43')
end
end

context 'with Forwaded header' do
Expand Down