[CentOS] CentOS-6 dhcpd

Timothy Murphy gayleard at eircom.net
Fri Jul 15 23:59:06 UTC 2011


Les Mikesell wrote:

>> But what puzzles me is, what defines the correspondence
>> between interface and network,
>> eg in my case eth1 ->  192.168.2.0/24
>>
>> Surely this should be there independently of dhcpd ?
>
> Dhcpd shouldn't care about the name of the interface, but if the request
> hasn't been forwarded by a router/relay agent it needs to figure out the
> subnet of the interface where the request is received so it uses the
> corresponding range and options for the response.

I'm not sure what router/relay agent is supposed to forward the request.

In my case, I am trying to run dhcpd on my CentOS-6 server,
but I get the message
------------------------------------
alfred dhcpd: No subnet declaration for eth1 (no IPv4 addresses).
alfred dhcpd: ** Ignoring requests on eth1.  If this is not what
alfred dhcpd:    you want, please write a subnet declaration
alfred dhcpd:    in your dhcpd.conf file for the network segment
alfred dhcpd:    to which interface eth1 is attached. **
alfred dhcpd:
alfred dhcpd:
alfred dhcpd: Not configured to listen on any interfaces!
------------------------------------

My /etc/dhcpd.conf reads (after removing comments and several hosts)
-------------------------------------
option domain-name "gayleard.com";
option domain-name-servers 208.67.222.222, 208.67.220.220;

default-lease-time 600;
max-lease-time 7200;

authoritative;

subnet 192.168.1.0 netmask 255.255.255.0 {
}

subnet 192.168.2.0 netmask 255.255.255.0 {

        authoritative;

        option routers                  192.168.2.1;
        option subnet-mask              255.255.255.0;

        option domain-name              "gayleard.com";
        option domain-name-servers      208.67.222.222,208.67.220.220;

        range 192.168.2.100 192.168.2.250;
        range dynamic-bootp 192.168.2.128 192.168.2.254;

        host alfred {
                hardware 00:1B:21:AB:C9:4C;
                fixed-address 192.168.2.2;
        }

        host blanche {
                hardware ethernet 00:1B:77:04:00:12;
                fixed-address 192.168.2.7;
        }

        host blanche-ether {
                hardware ethernet 00:36:6B:35:26:8E;
                fixed-address 192.168.2.27;
        }

        host linksys {
                hardware ethernet 00:16:B6:DA:56:B3;
                fixed-address 192.168.2.1;
        }

# several hosts omitted

}
-------------------------------------

In /etc/sysconfig/network-scripts/ I have
ifcfg-eth0
-------------------------------------
# Broadcom Corporation NetXtreme BCM5723 Gigabit Ethernet PCIe
DEVICE=eth0
HWADDR=3C:4A:92:77:B3:AE
IPADDR=192.168.1.2
GATEWAY=192.168.1.254
NETMASK=255.255.255.0
NM_CONTROLLED=no
ONBOOT=yes
BOOTPROTO=none
USERCTL=no
-------------------------------------
ifcfg-eth1
-------------------------------------
# Intel Corporation 82574L Gigabit Network Connection
DEVICE=eth1
TYPE=Ethernet
HWADDR=00:1B:21:AB:C9:4C
IPADDR=192.168.2.2
NETMASK=255.255.255.0
GATEWAY=192.168.2.1
NM_CONTROLLED=yes
ONBOOT=yes
BOOTPROTO=dhcp
IPV6INIT=no
USERCTL=yes
-------------------------------------

eth0 is connected to a Billion modem/router
and thence to the ethernet;
eth1 is connected to a Linksys WRT54GL router.

If anyone can point out the error of my ways
I should be most grateful.


-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland




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