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LLMNR is multicast resolution protocol. It is enabled in systemd-resolved since it has become default in f33 and provides Windows compatible resolution of names. It works over multicast on local networks and is potentially insecure. Any machine on the same network link can impersonate any hostname without dot present. But even Microsoft, which is behind its RFC has announced its deprecation [MS-LLMNR]. Ubuntu server has it disabled in default installation. I think we want that too. We do not want mdns, proposed replacement, enabled on servers by default either. What is not caused by the protocol itself, but the way systemd-resolved implements it, it directs single label names to LLMNR resolution *only*. So it also answers for queries not really intended for LLMNR resolution [stub-llmnr]. Reproducible: Always Steps to Reproduce: 1. resolvectl llmnr 2. dig -t ns org. Actual Results: # resolvectl llmnr Global: resolve Link 2 (eth0): resolve # dig -t ns org. ; <<>> DiG 9.18.17 <<>> -t ns org. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 45940 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;org. IN NS ;; Query time: 3580 msec ;; SERVER: 127.0.0.53#53(127.0.0.53) (UDP) ;; WHEN: Tue Aug 01 12:58:27 EDT 2023 ;; MSG SIZE rcvd: 32 Expected Results: # resolvectl llmnr Global: no Link 2 (eth0): no # dig -t ns org. ; <<>> DiG 9.18.17 <<>> -t ns org. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18927 ;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;org. IN NS ;; ANSWER SECTION: org. 3593 IN NS b2.org.afilias-nst.org. org. 3593 IN NS b0.org.afilias-nst.org. org. 3593 IN NS c0.org.afilias-nst.info. org. 3593 IN NS d0.org.afilias-nst.org. org. 3593 IN NS a0.org.afilias-nst.info. org. 3593 IN NS a2.org.afilias-nst.info. ;; Query time: 0 msec ;; SERVER: 127.0.0.53#53(127.0.0.53) (UDP) ;; WHEN: Tue Aug 01 12:59:53 EDT 2023 ;; MSG SIZE rcvd: 170 I have found also reference in cloud-init, disabling it explicitly in systemd-resolved template [init-resolved]. Created also ticket on fedora-server [1]. [MS-LLMNR] https://techcommunity.microsoft.com/t5/networking-blog/aligning-on-mdns-ramping-down-netbios-name-resolution-and-llmnr/ba-p/3290816 [init-resolved] https://github.com/canonical/cloud-init/blob/7cbe0f647737d9adf8635206b68f7fd363d67e0f/templates/systemd.resolved.conf.tmpl#L8 [1] https://pagure.io/fedora-server/issue/114 [stub-llmnr] https://github.com/systemd/systemd/issues/23622
This bug appears to have been reported against 'rawhide' during the Fedora Linux 39 development cycle. Changing version to 39.
As mentioned in the linked server WG ticket, we should start this as a change proposal. I have created a clone of the template [1]. I am happy to help and make this change happen. [1] - https://fedoraproject.org/wiki/Changes/Disable_LLMNR_name_resolution
This bug appears to have been reported against 'rawhide' during the Fedora Linux 42 development cycle. Changing version to 42.
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Fedora Linux 42 entered end-of-life (EOL) status on 2026-05-27. Fedora Linux 42 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora Linux please feel free to reopen this bug against that version. Note that the version field may be hidden. Click the "Show advanced fields" button if you do not see the version field. If you are unable to reopen this bug, please file a new report against an active release. Thank you for reporting this bug and we are sorry it could not be fixed.