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

[Bill Shirley]

I would suggest setting wlp2s0 as a different subnet, say 10.1.2.1/24
and create an additional subnet declaration in DHCP with option routers
10.1.2.1.  'yellow' should route between 10.1.1.0/24 and 10.1.2.0/24
for your internal devices.

Bill

On 1/27/2018 4:10 PM, A wrote:
>
>
>
> 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.
>
>
>
>
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