Possible DHCP Issues

MikeV7896 · Mar 1, 2016, 10:40 PM

Just thought I'd mention that I'm seeing this issue as well. I have two Apple devices that usually show hostnames (and always did under 2.2.6), but now after running 2.3 for a few days, neither is showing a hostname in the DHCP Leases table.

cmb · Mar 2, 2016, 1:39 AM

Anything that's happening here is something to do with dhcpd itself, nothing in our code has any relation. The change from dhcpd 4.2 to 4.3 is probably at fault I'd guess, since that's the only thing that's changed. After a bit of searching I don't see any mention of issues along those lines in dhcpd or any relevant changes in behavior.

MikeV7896 · Mar 2, 2016, 2:02 AM

Now that you've mentioned that, I checked the dhcpd.leases file and it doesn't have hostnames for the (now) three devices that don't have hostnames in the pfSense list… so I guess it must be something in dhcpd...

AsgardianFW · Mar 2, 2016, 2:17 AM

Is dhcpd capable of doing any kind of debug logging so that we can ascertain under what conditions it feels obligated to remove the hostname? If so, how can I enable it?
In a previous post, I mentioned that the same IP lease will be listed twice in dhcp.leases (one with a hostname and one without and each entry has different lease/expire times). Is this expected behavior?

(Please forgive my ignorant questions. I'm a Windows developer and FreeBSD isn't in my core skill set.)

AsgardianFW · Mar 2, 2016, 3:00 AM

As an added FYI…I checked a couple of my 2.2.5 installations and while the dhcp.leases file seems correct all the time on those, the /var/unbound/dhcpleases_entries.conf file seems to lose the occasional entry similar to the way 2.3 does in both files.

AsgardianFW · Mar 7, 2016, 7:47 PM

I'm still interested in trying to diagnose this problem. Is it possible for me to go back to dhcpd 4.2 in pfSense 2.3 to see if the problem still happens? This could help narrow down if there were changes in 4.3 that caused this.

gsiemon · Mar 7, 2016, 11:31 PM

I've just upgraded from 2.2.6 to 2.3 over the weekend and I'm seeing the same problem. Some of my devices are no longer showing hostnames in dhcpd.leases. This seems to affect all of our iOS and OS X devices

I have managed to get them to show up for a short time by editing their hostnames and then forcing a lease renewal on the client but a short time later (I suspect its when the device sleeps or goes out of range) it disappears again. I never saw this behaviour on 2.2.6.

dhcpd is configured with default settings for lease times etc. I do register the leases in a DNS server (not pfsense) and the leases file correctly lists the hostname in the FQDN registered in DNS for every device (affected or otherwise).

The only common thing I can see at the moment (and this may be a red herring) is that all of the devices that seem to have missing hostnames have 24 hour leases. The ones that seem to have sticky hostnames only have 2 hour leases.

cmb · Mar 8, 2016, 7:06 PM

I found one situation where it'll put in a lease entry with no hostname. If you 'ipconfig/release' on Windows, you end up with a "binding state free" lease entry like:

lease 192.168.1.100 {
  starts 2 2016/03/08 00:45:14;
  ends 2 2016/03/08 01:10:17;
  tstp 2 2016/03/08 01:10:17;
  cltt 2 2016/03/08 00:45:14;
  binding state free;
  hardware ethernet 00:0c:29:49:35:f4;
  uid "\001\000\014)I5\364";
}

but dhcpleases still finds the earlier leases and registers the hostname from the leases prior to the release.

Asgardian: if you still have the pcap files from earlier, could you send me those?

The full contents of your dhcpd.leases file from anyone that's affected would be helpful as well.

AsgardianFW · Mar 20, 2016, 1:08 PM

cmb,
I was just checking in to see if you figured out anything from the info I sent? I can still do more debugging for you if needed. Just let me know. Thanks.

cmb · Jul 8, 2016, 5:10 AM

Added a bug ticket for this issue, as there definitely is something to it.
https://redmine.pfsense.org/issues/6589