的 DNS 出包

Hacker News Daily 上的「Tell HN: added to their DNS record」這邊看到的,看起來是某種 misconfiguration 造成 microsoft.comA record 除了給正常的 IPv4 address 外,還給出了 的 IPv4 address。

不過裡面比較有趣的是 id=38704301 這個,提到他反而查不到,看 log 發現被 dnsmasq 認定是 DNS rebinding 的攻擊而擋下來不回應任何 IP address:

I was getting an empty answer for Turns out my dnsmasq is blocking it:

  $ dig | grep EDE
  ; EDE: 15 (Blocked)

  resolver.log:Dec 20 00:43:57 router dnsmasq[8172]: possible DNS-rebind attack detected:

翻了 dnsmasq 的 manpage,可以看到這個功能:


Reject (and log) addresses from upstream nameservers which are in the private ranges. This blocks an attack where a browser behind a firewall is used to probe machines on the local network. For IPv6, the private range covers the IPv4-mapped addresses in private space plus all link-local (LL) and site-local (ULA) addresses.

id=38704159 這邊也有類似的情況,不過這邊是提到 OpenWrt is currently IPv6-only on my network, because OpenWrt's DNS rebinding protection filters out the A records:

  $ ping -4
  ping: Address family for hostname not supported

  $ ping -6
  PING (2603:1030:c02:8::14)) 56 data bytes
  64 bytes from 2603:1030:c02:8::14 (2603:1030:c02:8::14): icmp_seq=1 ttl=112 time=68.4 ms