[SOLVED] RT-AC3200 FreeBSD client shows MAC address in client list, not hostname

[cmkelley]

I hesitated to ask here, since the only computer on my network that does this is a FreeBSD machine, but maybe understanding the underlying behavior will help me track it down. I searched the forums as best I could, but I didn't find anything more than "sometimes this happens".

I am using a RT-AC3200, with asuswrt-merlin (but I think this has nothing to do with the firmware, so posting here for a wider audience). My network is a mix of windows, freebsd, android, and linux, both wired as well as wireless. I have one FreeBSD machine I use to backup my primary fileserver, which is NAS4Free, which also runs on FreeBSD. Both my fileserver and backup machines are running the same version and patchlevel of FreeBSD.

THE ISSUE: Everything on my network, except the backup machine, correctly displays the hostname from the device on the client list (i.e. without manually setting it in asuswrt), even my fileserver. The backup machine lists the MAC address as the client name.

I attempted to see what's different about NAS4Free's implementation, but couldn't find anything in the NAS4Free configuration files that gave me a hint. There are some similarities and some differences between the two;

Similarities
- Both using FreeBSD 10.2-RELEASE-p8
- Both wired
- Both use same brand NIC (Intel gigabit) (can't possibly see how this could be related)
- I have set IPv4 addresses for both on the machines, although I do use DHCP for some other devices.

Differences
- Backup machine gets an IPv6 address, fileserver does not. But, I have other devices that get IPv6 addresses as well and they work
- Fileserver is using smb/cifs, backup is not (backup accesses fileserver over NFS). But not all other devices on my network use smb/cifs.
- Backup machine goes through a gigabit switch before going to AC3200, fileserver gets one of the ports on the AC3200. But, other machines go through the switch first. (can't possibly see how this could be related)
- Fileserver has many services running, backup machine is only for backup.

So my question is, assuming someone doesn't know what the issue is right off, how are the client names obtained by asuswrt? I'm wondering if there's some system value or DHCP option the fileserver could be setting that the backup machine is not? Of if there's a port I need to specifically open on the backup machine?

Yes, I know I can just manually set the hostname in the setup, but what fun would that be? Being a geek/nerd and naturally curious by nature, it's really got me wondering what's different about that machine. It is the only machine on my network that does this, and it does it consistently, so it's not just some crazy bug.

Thanks!

 

[ColinTaylor]

Sorry, it is not clear to me where you are seeing the "MAC address instead of hostname". Is it on your backup server or the ASUS?

If it's the ASUS:

The router mainly resolves client names from its own DNS server (dnsmasq), but it also uses other methods I believe (local hosts file, NetBIOS broadcasts, etc). Commonly a client will register its name with the routers DNS as part of its DHCP negotiation. If the client doesn't register its name (or it's a stupid name) you can change it by creating a IP reservation on the LAN/DHCP page of the router. So, if your client doesn't register its name through DHCP and isn't broadcasting it's name via NetBIOS, how is the router supposed to know the name?

 

[cmkelley]

Sorry, yes, on the ASUS, in the client list.

Yeah, I know I can fix it in the router. I'm just curious as to why it's happening when I have two FreeBSD computers running the same version and patchlevel, and one registers the name in the router's DNS and one doesn't. It's not "broke", it's more of a technical question of how does the router figure out the host name, and why is one computer registering and the other not.

 

[ColinTaylor]

Similarities
- I have set IPv4 addresses for both on the machines, although I do use DHCP for some other devices.

Differences
- Backup machine gets an IPv6 address, fileserver does not. But, I have other devices that get IPv6 addresses as well and they work
- Fileserver is using smb/cifs, backup is not (backup accesses fileserver over NFS). But not all other devices on my network use smb/cifs.

It sounds like neither machine is using DHCP. Correct? In which case they will not be registering their names with DNS. One of the machines is running Samba so it will be broadcasting its NetBIOS name which the router can detect.

 

[cmkelley]

Yes, both have static IPv4 address. I don't understand enough about IPv6 to speak intelligently, but the IPv6 address are allocated by the router, maybe that's not a two-way communication like IPv4 DHCP is?

I guess that makes sense. But I would have expected the router's IPv6 allocation would have asked for the hostname. Perhaps not.

 

[ColinTaylor]

I guess that makes sense. But I would have expected the router's IPv6 allocation would have asked for the hostname. Perhaps not.

Good point. I don't know how IPv6 works.

 

[cmkelley]

That was it. I put just enough of samba in place on the backup machine to reply to NetBIOS requests and now the router finds and displays the hostname. So, apparently, IPv6 doesn't respond with the hostname when getting an IPv6 address from the router. I learned something this week. Yay!