[CentOS] Centos 7 dhcpd failure to allow a 2nd network over same interal nic

Mon Jan 16 09:42:52 UTC 2017
John R Pierce <pierce at hogranch.com>

On 1/16/2017 1:29 AM, Rob Kampen wrote:
> On 16/01/17 21:54, John R Pierce wrote:
>> On 1/16/2017 12:44 AM, Rob Kampen wrote:
>>> Here's an idea - untested.
>>> set up a network on the single nic - say 192.168.55.xx/24
>>> set up the dhcp to offer leases from a subset of this network - say 
>>> set up fixed leases based upon mac address from the remainder of the 
>>> network - i.e. outside the subset above - e.g.
>>> then route / firewall as required - i.e. trusted known mac address 
>>> hence IP address allowed vs unknown guest given an IP address we can 
>>> block or otherwise handle.
>>> As indicated, this is not tested but if memory serves, dhcpd will 
>>> allow this kind of allocation. 
>> the untrusted wireless users will be able to access other LAN 
>> machines without going through the firewall.
> surely that depends upon the subnet they operate on (i.e the subnet 
> mask in old vernacular) - the two I show above are mutually exclusive 
> but can both talk to the server.

you can't mix subnets like that.     it just won't work.   the local 
broadcast address for the /24 isn't in either of your /28's, and what do 
the two /28's use for their default gateway ?

john r pierce, recycling bits in santa cruz