No subnet declaration; Can't open /var/lib/dhcp/dhcpd.leases for append

A publicface at bak.rr.com
Sat Jan 27 21:10:09 UTC 2018



On 01/27/2018 11:57 AM, Simon Hobson wrote:
> A <publicface at bak.rr.com <mailto:publicface at bak.rr.com>> wrote:
>
>> # ip -4 -o addr
>>
>> 1: lo    inet 127.0.0.1/8 scope host lo\       valid_lft forever 
>> preferred_lft forever
>> 2: enp4s5    inet 10.1.1.1/24 brd 10.1.1.255 scope global 
>> enp4s5\       valid_lft forever preferred_lft forever
>> 3: enp6s0    inet [xx.xx.xx.xx/20 brd 255.255.255.255 scope global 
>> enp6s0\       valid_lft forever preferred_lft forever
>> 4: wlp2s0    inet 10.1.1.10/24 brd 10.1.1.255 scope global 
>> wlp2s0\       valid_lft forever preferred_lft forever
>> ...
>> Jan 27 10:37:48 yellow sh[5804]: No subnet declaration for enp4s5 (no 
>> IPv4 addresses).
>> Jan 27 10:37:48 yellow sh[5804]: ** Ignoring requests on enp4s5.  If 
>> this is not what
>> Jan 27 10:37:48 yellow sh[5804]:    you want, please write a subnet 
>> declaration
>> Jan 27 10:37:48 yellow sh[5804]:    in your dhcpd.conf file for the 
>> network segment
>> Jan 27 10:37:48 yellow sh[5804]:    to which interface enp4s5 is 
>> attached. **
>> Jan 27 10:37:48 yellow dhcpd[5804]: No subnet declaration for enp4s5 
>> (no IPv4 addresses).
>> Jan 27 10:37:48 yellow dhcpd[5804]: ** Ignoring requests on enp4s5.  
>> If this is not what
>> Jan 27 10:37:48 yellow dhcpd[5804]:    you want, please write a 
>> subnet declaration
>> Jan 27 10:37:48 yellow dhcpd[5804]:    in your dhcpd.conf file for 
>> the network segment
>> Jan 27 10:37:48 yellow dhcpd[5804]:    to which interface enp4s5 is 
>> attached. **
>> Jan 27 10:37:48 yellow dhcpd[5804]:
>> Jan 27 10:37:48 yellow dhcpd[5804]: Listening on 
>> LPF/wlp2s0/f0:7d:68:c1:b4:13/10.1.1.0/24
>> Jan 27 10:37:48 yellow dhcpd[5804]: Sending on 
>> LPF/wlp2s0/f0:7d:68:c1:b4:13/10.1.1.0/24
>> Jan 27 10:37:48 yellow sh[5804]: Listening on 
>> LPF/wlp2s0/f0:7d:68:c1:b4:13/10.1.1.0/24
>> Jan 27 10:37:48 yellow sh[5804]: Sending on 
>> LPF/wlp2s0/f0:7d:68:c1:b4:13/10.1.1.0/24
>> Jan 27 10:37:48 yellow sh[5804]: Sending on Socket/fallback/fallback-net
>> Jan 27 10:37:48 yellow dhcpd[5804]: Sending on 
>> Socket/fallback/fallback-net
>> Jan 27 10:37:48 yellow dhcpd[5804]: Server starting service.
>
> Hmm, I have an idea what the problem might be. You have two interfaces 
> in the same subnet and I don't think the dhcp server can handle that. 
> The OS can deal with it because it keeps an ARP cache and so can 
> figure out which interface to use for outbound packets.
> BUT, ISC DHCPD doesn't use the OS for routing a lot of it's packets - 
> it works at a lower level as it has to be able to send packets which 
> wouldn't ordinarily be routable (no destination IP address) to clients.
>
> So what I think might be happening is that it's connecting the 
> 10.1.1.0/24 subnet with the wlp2s0 interface, and then when it tries 
> to configure the enp4s5 interface, there is no subnet available to 
> connect with it
>

Sounds reasonable.  And therefore if I was to force it to use enp4s5 
somehow, there'd be no subnet for wlp2s0; right?

I did originally have two separate subnets with a /28 CIDR, but I was 
unable to reach the Internet from blue and someone suggested I have one 
subnet in order to act as a typical home router. So I reconfigured 
everything and it's now borked worse than it was.  Said person 
disappeared shortly after of course.

> I'm assuming this box is permanently connected to both networks ? If 
> not then it wouldn't be very useful as a DHCP server.

Yellow - yes.

> Is there another device bridging the ethernet and WiFi ?

Not anymore.  There was a virtual bridge using bridge-utils at one point 
as mentioned above.  Wouldn't be impossible to put it back.

> I assume there's an AP

I'm using hostapd as I'm unaware of any other option for AP software at 
this time.

> , or it's built into the router - and in that case, you do not need 
> (for DHCP anyway) to listen on the WiFi interface since packets will 
> get bridges to the ethernet interface by the AP.

There is no commercial router.  Yellow is the router, gateway, access 
point, dhcp server, dns server, firewall (iptables) and more.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/dhcp-users/attachments/20180127/7865e21f/attachment.html>


More information about the dhcp-users mailing list