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DNS Forwarding Services not responding with Allow-From
Closed, InvalidPublicBUG


When configuring the DNS Forwarding Service, 'allow-from' is now a required parameter, committing the configuration fails when this is not specified. This is fine, however during my testing only the /32 and /0 network prefix lengths caused the DNS Service to respond. Note I am using and exclusively testing this using an IPv4 network.

When specifying a standard network prefix length to cover the entire network, such as or, it is successfully accepted and commits without errors, however the DNS Forwarding Service does not respond.

When specifying the /32 prefix length, I specified a single private IP address that was on the internal network, the IP address of the client computer I was testing from. When I specified this, that single client computer was able to successfully query the service (as expected).

When specifying the /0 prefix length, using '' the service successfully responds to requests on the local network.

I'm not sure if this is intentional, however I'm thinking it's not. I did not try all network prefixes, however I covered a large handful of common ones I experience, and only /32 and /0 caused the service to respond.

My configuration is as follows:

service {
	dns {
		forwarding {
			cache-size 0


Difficulty level
Unknown (require assessment)
Why the issue appeared?
Will be filled on close
Is it a breaking change?
Unspecified (possibly destroys the router)

Event Timeline

syncer changed the task status from Open to Needs testing.Nov 16 2019, 11:39 PM
syncer assigned this task to zsdc.
syncer triaged this task as Normal priority.
syncer edited projects, added VyOS 1.3 Equuleus; removed VyOS 1.2 Crux.
zsdc reassigned this task from zsdc to Unknown Object (User).Apr 3 2020, 11:48 AM
zsdc added a subscriber: zsdc.
Unknown Object (User) closed this task as Invalid.Apr 5 2020, 9:42 AM

I was not able to recreate that issue. Both /24 and /8 networks were tested.
All the tests have been done on the VyOS 1.3-rolling-202004020117.