Cannot use 127.0.0.1 as private rDNS server (but adding port fixes it)

[mxk]

Prerequisites

• I have checked the Wiki and Discussions and found no answer

• I have searched other issues and found no duplicates

• I want to report a bug and not ask a question or ask for help

• I have set up AdGuard Home correctly and configured clients to use it. (Use the Discussions for help with installing and configuring clients.)

Platform (OS and CPU architecture)

OpenBSD, AMD64 (aka x86_64)

Installation

GitHub releases or script from README

Setup

On a router, DHCP is handled by the router

AdGuard Home version

0.107.38

Action

Configured 127.0.0.1 under "Private reverse DNS servers" (local_ptr_upstreams), which is my dnsmasq server.

If I change the server IP to either 127.0.0.1:53 or 10.0.0.1, both of which point to the same dnsmasq instance, then everything works correctly.

Expected result

PTR queries for private IPs should be forwarded to dnsmasq and resolved correctly.

Actual result

I get a SERVFAIL response. Adding :53 to the upstream server IP fixes the problem.

Additional information and/or screenshots

Debug log output:

[debug] dnsproxy: handling new udp packet from 10.0.0.3:11768
[debug] github.com/AdguardTeam/dnsproxy/proxy.(*Proxy).logDNSMessage(): IN: ;; opcode: QUERY, status: NOERROR, id: 12254
;; flags: rd ad; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version 0; flags:; udp: 4096

;; QUESTION SECTION:
;1.1.0.10.in-addr.arpa.        IN       PTR

dnsforward: started processing recursion
dnsforward: finished processing recursion
dnsforward: started processing initial
applying filters: looking for client with ip 10.0.0.3 and clientid ""
applying filters: no clients with ip 10.0.0.3 and clientid ""
clients: processing 10.0.0.3 with rdns
dnsforward: finished processing initial
dnsforward: started processing ddr
clients: finished processing 10.0.0.3 with rdns in 175.332M-BM-5s
dnsforward: finished processing ddr
clients: processing 10.0.0.3 with whois
clients: finished processing 10.0.0.3 with whois in 26.731M-BM-5s
dnsforward: started processing local detection
dnsforward: finished processing local detection
dnsforward: started processing dhcp hosts
dnsforward: finished processing dhcp hosts
dnsforward: started processing local restriction
dnsforward: addr 10.0.1.1 is from locally served network
dnsforward: finished processing local restriction
dnsforward: started processing dhcp addrs
dnsforward: finished processing dhcp addrs
dnsforward: started processing filtering before req
dnsforward: finished processing filtering before req
dnsforward: started processing local ptr
dnsproxy: cache: disabled; not caching
dnsforward: resolving private address: selecting general upstream: no upstream specified
dnsforward: finished processing local ptr
github.com/AdguardTeam/dnsproxy/proxy.(*Proxy).logDNSMessage(): OUT: ;; opcode: QUERY, status: SERVFAIL, id: 12254
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;1.1.0.10.in-addr.arpa.        IN       PTR

[EugeneOne1]

@mxk, hello and apologies for delayed response. We've tried to fix it in the latest edge build, so could you please try it? AdGuard Home should now consider the port while filtering its own listening addresses from private upstreams.

[mxk]

Can confirm that this is fixed in the edge build. Thanks!