[Dnsmasq-discuss] [PATCH] Add CG-NAT range to non-globally routed IP space per RFC7793

Rob Gill rrobgill at protonmail.com
Tue Jun 24 22:16:04 UTC 2025


The Shared address space (100.64.0.0/10) used by CG-NAT, defined in RFC6598 should
not have reverse DNS queries sent to global DNS infrastructure.

Confirmed in RFC7793 and listed on
https://www.iana.org/assignments/locally-served-dns-zones/locally-served-dns-zones.xhtml

Signed-off-by: Rob Gill <rrobgill at protonmail.com>
---
 src/rfc1035.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/rfc1035.c b/src/rfc1035.c
index bb63083..5f316d8 100644
--- a/src/rfc1035.c
+++ b/src/rfc1035.c
@@ -415,6 +415,7 @@ int private_net(struct in_addr addr, int ban_localhost)
     (((ip_addr & 0xFF000000) == 0x7F000000) && ban_localhost)  /* 127.0.0.0/8    (loopback) */ ||
     (((ip_addr & 0xFF000000) == 0x00000000) && ban_localhost) /* RFC 5735 section 3. "here" network */ ||
     ((ip_addr & 0xFF000000) == 0x0A000000)  /* 10.0.0.0/8     (private)  */ ||
+    ((ip_addr & 0xFFC00000) == 0x64400000)  /* 100.64.0.0/10  (CG-NAT) RFC6598/RFC7793*/ ||
     ((ip_addr & 0xFFF00000) == 0xAC100000)  /* 172.16.0.0/12  (private)  */ ||
     ((ip_addr & 0xFFFF0000) == 0xC0A80000)  /* 192.168.0.0/16 (private)  */ ||
     ((ip_addr & 0xFFFF0000) == 0xA9FE0000)  /* 169.254.0.0/16 (zeroconf) */ ||
-- 
2.34.1





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