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

[A]

On 01/27/2018 01:28 PM, Simon Hobson wrote:
> A <publicface at bak.rr.com <mailto:publicface at bak.rr.com>> wrote:
>
>> 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.
>>
>> There is no commercial router.  Yellow is the router, gateway, access 
>> point, dhcp server, dns server, firewall (iptables) and more.
>
> OK, so this box is your gateway, AP, etc, etc. In that case I believe 
> that your setup is fundamentally broken - you have TWO SEPARATE 
> networks (one wired, one wireless) running the same subnet.

Yes, that's how I was told to set it up by a helpful individual.  I was 
told since it was one subnet, no routing would be needed.  The wireless 
& wired interfaces would be bridged.  Seemed reasonable.  It sounds like 
you are suggesting exactly the same thing so "fundamentally broken" 
seems a bit harsh.

> Thus devices on the wired network cannot talk to devices on the WiFi 
> and vice-verca.
>
> Bear in mind that I've not used WiFi in this manner (I'm used to using 
> external APs), so I am unsure of some of the details. If you want to 
> run a single unified network then you will need to create a bridge, 
> and put the wired and wireless adapters into that bridge - and put 
> your address 10.1.1.1/24 onto the bridge. You will then have one 
> network, and the bridge software will pass packets between them, as 
> well as keeping track of which clients are in which network segment.

I removed the bridge because I was unable to reach the Internet from 
yellow (nor blue).  And that is how things stand now.  Bridge up, 
Internet down.  Bridge down, Internet up.


>
> As far as (almost) all software on your box is concerned, you just 
> deal with one interface (the bridge, eg br0). What I am unsure about 
> is how dhcpd behaves in this case - hopefully someone who's run this 
> setup can comment ? I would hope that it would use the bridge 
> interface in the same manner as it would use a "real" one, but there 
> can be some subtle differences.

I had it working with the bridge at one point - each box could ping the 
other on both wired & wireless, but blue couldn't reach the Internet.  
Lets see if we can put it back.

.... blue now receives an IP of .14; neither machine can ping the other, 
though each can ping its own assigned IP.

# brctl show
bridge name    bridge id        STP enabled    interfaces
br0        8000.7085c23b1324    no                   enp4s5
                enp6s0


$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
group default qlen 1000
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
     inet 127.0.0.1/8 scope host lo
        valid_lft forever preferred_lft forever
     inet6 ::1/128 scope host
        valid_lft forever preferred_lft forever
2: enp4s5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast 
master br0 state UP group default qlen 1000
     link/ether c8:3a:35:da:42:72 brd ff:ff:ff:ff:ff:ff
     inet 10.1.1.1/24 brd 10.1.1.255 scope global enp4s5
        valid_lft forever preferred_lft forever
3: enp6s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast 
master br0 state UP group default qlen 1000
     link/ether 70:85:c2:3b:13:24 brd ff:ff:ff:ff:ff:ff
     inet [xx.xx.xx.xx]/20 brd 255.255.255.255 scope global enp6s0
        valid_lft forever preferred_lft forever
     inet6 fe80::7285:c2ff:fe3b:1324/64 scope link
        valid_lft forever preferred_lft forever
4: wlp2s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue 
state DOWN group default qlen 1000
     link/ether f0:7d:68:c1:b4:13 brd ff:ff:ff:ff:ff:ff
     inet 10.1.1.10/24 brd 10.1.1.255 scope global wlp2s0
        valid_lft forever preferred_lft forever
5: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state 
UP group default qlen 1000
     link/ether 70:85:c2:3b:13:24 brd ff:ff:ff:ff:ff:ff
     inet 10.1.1.1/24 brd 10.1.1.255 scope global br0
        valid_lft forever preferred_lft forever
     inet6 fe80::7285:c2ff:fe3b:1324/64 scope link
        valid_lft forever preferred_lft forever

# ip route
default via 174.xx.yy.1 dev enp6s0
10.1.1.0/24 dev enp4s5  proto kernel  scope link  src 10.1.1.1
174.xx.yy.0/20 dev enp6s0  proto kernel  scope link  src 174.xx.bb.zz


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