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So far, I have avahi-daemon running on all my Ubuntu machines, partly because it is installed by default. The router I used to have was quite dumb and did not really do anything except DHCP and DHCPv6. I could access the other Linux computers with hostname.local which worked fine for my purposes.

Now I have an AVM FRITZ!Box 7360 which also does some more regarding hostnames as I can access the Linux machines with hostname.fritz.box in my local network as well.

For some reason, I also can do the following now (Linux → Windows):

$ ping martin-pavilion.local
PING martin-pavilion.local (192.168.188.28) 56(84) bytes of data.
64 bytes from Martin-Pavilion.fritz.box (192.168.188.28): icmp_seq=1 ttl=128 time=0.633 ms

The martin-pavilion is running Windows 8. I do not think that it was accessible via .local previously, and the FRITZ!Box seems to translate the .local into the .fritz.box.

What is happening here? I somewhat got that Zeroconf/Avahi/Bonjour managed to let every computer know about every other one. Does the FRITZ!Box do the same or is this different?

My /etc/resolv.conf is:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.1.1
search fritz.box
Martin Ueding
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1 Answers1

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The FritzBox home router is using DHCP requests to update the FritzBox's DNS forwarding. Specifically: if there is a hostname option provided in the DHCP request then a hostname.fritz.box DNS record is provided by the FritzBox's DNS forwarding.

This is distinct from mDNS's .local domain. The FritzBox is not a mDNS proxy server.

vk5tu
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  • Does this mean in simple words that my tries to ping *xxx.local* will not work if my router is a fritz.box? I have an mDNS setup on an embedded device, but I am not able to reach it for some reason. Is it because mDNS is not supported in fritz.box? – Mohammed Noureldin Nov 08 '20 at 04:04
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    In simple words: mDNS within a single subnet doesn't need support in the router, so the manufacturer doesn't matter. All that matters is that subnet broadcasts sent by one host are seen by all other hosts. Those broadcasts can sometimes be prevented if "host isolation" or "P2P blocking" is set in the access point. On the FritzBox set "Wireless | Security | The active wireless devices displayed below may communicate with each other". – vk5tu Nov 09 '20 at 09:59
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    Thank you for your reply, this is weird, this option is selected, never the less mDNS does not work in my case for ESP chip. I have to investigate this further. Thank you! – Mohammed Noureldin Nov 09 '20 at 11:01
  • @MohammedNoureldin Yes, .local will work, fortunately it does not need the fritz. But you need an mdns responder on your devices. On Linux, it can be done by avahi. On Windows, it needs a policy setting. Afaik ios has it by default (never tried). Android probably can do it only by rooting the thing. Btw, if you have a choice in the future, avoid fritz. – peterh Oct 06 '21 at 00:28
  • @peterh Avoid it why? – Robert Siemer Dec 23 '21 at 22:07
  • @RobertSiemer Because it is the exact opposite of what an open source enthusiast (and, in a more beoad sense, an enthusiast of a society based on creativity and not on slavery) would expect from such a thing. This little comment is not enough for a complete listing but I will do it multiple comments if you wish it. Many people in the opensource world dislikes microsoft, while many companies are more harmful. Imho, apple and fritz are worser than the ms (if such a comparison can be done). – peterh Dec 24 '21 at 01:07