Synology DCHP / DNS update script broken in DSM 6.0-7321

[chriscjcj]

The script that takes the Synology DHCP database and creates DNS A records from them is unfortunately broken in DSM 6. The script runs and deletes all A records from the DNS zone file, but it no longer repopulates it. So, if you update to DSM 6, beware... you'll have an empty zone file. I attempted to reach out to Tim Smith through the Synology forums, but his last post was in 2014 and he hasn't responded yet. I have been trying to figure this one out myself, but I'm in over my head. Any chance you could take a look at it and see if you can figure out why it's not working?

The original thread where this script was discussed can be found here:
https://forum.synology.com/enu/viewtopic.php?f=233&t=88517&p=429340

Many thanks,
-Chris Johnson

[zimmerlis]

Hi Chris, I have had the same issue, and I have found a solution.
If you run the script in DSM v6 on the console then the following erorr is shown:

awk: cmd. line:5: fatal: cannot open file `/etc/dhcpd/dhcpd-static-static.conf' for reading (No such file or directory)

The name of the DHCPStatic file containing the reservations has changed:
/etc/dhcpd/dhcpd-eth0-static.conf

So change the line contains the "DHCPStatic" in your script:
from: DHCPStatic=/etc/dhcpd/dhcpd-static-static.conf
to: DHCPStatic=/etc/dhcpd/dhcpd-eth0-static.conf

On my DSM v6 this script workes again as before! :-)

Regards, Rene

[gclayburg]

Good catch, guys. I haven't yet tried this on DSM 6, but I plan to shortly. I'll update these scripts so that they work on both DSM 5 and 6. Testing might be a bit tricky though, since I only have one synology server to work with.

[chriscjcj]

Rene, Thank you so very much for posting this! It works for me as well. I shall post this fix in the Synology forum where this script was originally discussed.

[gclayburg]

Or better yet, @zimmerlis , could you create a pull request from with your script update?

[chriscjcj]

I'll update these scripts so that they work on both DSM 5 and 6. Testing might be a bit tricky though, since I only have one synology server to work with.

I will be happy to test it on DSM 6. Just let me know. 👍

[gclayburg]

@chriscjcj @zimmerlis I wonder if you guys are using an older version of this script. I added error checking quite some time ago to first check for the existence of the DHCP static leases file.

BTW, I just also updated the script to also check for leases that may exist in the /etc/dhcpd/dhcpd-eth0-static.conf file. @chriscjcj can you verify that this script now works under DSM 6?

[chriscjcj]

I was indeed using a rather old version of this script. I have updated with the most current revision. (3317c4e) I deleted several A records from the zone file which were based on DHCP lease reservations. I then ran the script. The script successfully repopulated the zone file with all of the host names from the DHCP server. So near as I can tell, it works beautifully.

THANK YOU for your assistance on this. I'm truly grateful. If you ever find yourself in San Francisco, please let me know. I'll buy you a beer. :-)

P.S. Just installed DSM 6.0-7321 Update 2. Script works fine under both the initial DSM6 release as well as this "update 2."

[tonysurma]

First off thanks for this! It is working great for me. One note on above in DSM 6.0 it appears that it went from a single static file to one per interface that DHCP is configured on. For example: I have DHCP only on the 4th Ethernet adapter (eth3) and so I don't have a -static-static or a -eth0-static and instead only have a -eth3-static. So it looks like the fix for 6.0 would be to add in static entries from any file -ethX-static.

I have a potential pull request for this but I think there would have to be a decision of do we have this concatenate together all ethX or make it a setting to pick which one (defaulting to eth0)?

I could imagine a world where someone wants different reverse zones updated from different ethX files if there are different IP ranges on multiple NICs... but maybe that isn't an issue...

[gclayburg]

On my system, I notice static dhcp-host addresses appear in both /etc/dhcpd/dhcpd-static-static.conf and /etc/dhcpd/dhcpd.conf. Both of these files are scanned by the script as it is now. @tonysurma does your system have duplicate dhcp-host entries?

My system uses the name "bond0" as the interface name. Maybe the simplest thing to do here is just look for dhcp-host entries in any /etc/dhcpd/dhcpd*static.conf file.

[tonysurma]

on mine DS1515 on 6.1 I have nothing in dhcpd.conf and just in the static.conf file(s) (in my case only eth3 as I only have it live on my 4th NIC.

That all being said I just ran the current versions from your repo and all works properly so looks like it is fixed (for me at least)

Apologies for delay in testing but I think this can be closed - thanks again @gclayburg

[gclayburg]

For you folks running DSM 6, you might check the latest version just committed. @WolfspiritM created a PR that does a better job of determining network interfaces on your system.