sending options from wrong subnet in shared-network

Glenn Satchell glenn.satchell at uniq.com.au
Fri Dec 6 01:50:19 UTC 2013


Your-IP 10.14.81.56 is not even in the dynamic range, so I wouldn't trust
anything the dhcp client has. Maybe need to release the ip lease on the
client and get a new one to see what you get.

Could also try putting a pool {} block around all the items in each subnet
definition. This might help by changing the scope to a higher precedence.

Typically these days you don't need the dynamic-bootp option for the range
statement. RedHat has that in the default example file, but just a plain
range would be fine. Bootp never expires a lease, so you can exhaust your
pool with old clients that have gone away still holding onto IPs for ever.

At the bottom of your list the host statement has ip in 192.168.0.0 subnet
and router in the 10.14.80.0 one, so that won't ever work.

regards,
-glenn

On Fri, December 6, 2013 12:50 am, Brian J. Murrell wrote:
> I have a shared network configuration that looks like this:
>
> shared-network foo {
>     subnet 192.168.0.0 netmask 255.255.255.0 {
>          option routers             192.168.0.1;
>          option domain-name         "subdomain.example.com";
>          option domain-name-servers 192.168.0.4;
>          option subnet-mask         255.255.255.0;
>          default-lease-time         21600;
>          max-lease-time             43200;
>     }
>     subnet 10.14.80.0 netmask 255.255.248.0 {
>          option routers             10.14.80.1;
>          option domain-name         "subdomain.example.com";
>          option domain-name-servers 10.14.80.8, 10.14.80.9, 10.14.80.6;
>          option subnet-mask         255.255.248.0;
>          range dynamic-bootp        10.14.80.100 10.14.83.254;
>          default-lease-time         21600;
>          max-lease-time             43200;
>          next-server                10.14.80.6;
>     }
> }
>
> The problem is that clients seem to be getting an address from one
> network and options from the other in their reply:
>
> 08:19:07.216363 52:54:00:0f:ce:31 > 52:54:00:19:d9:08, ethertype IPv4
> (0x0800), length 344: (tos 0x10, ttl 128, id 0, offset 0, flags [none],
> proto UDP (17), length 330)
>     10.14.80.6.bootps > 10.14.81.56.bootpc: BOOTP/DHCP, Reply, length 302,
> xid 0x19d908, Flags [none]
>           Your-IP 10.14.81.56
>           Server-IP 10.14.80.6
>           Client-Ethernet-Address 52:54:00:19:d9:08
>           file "/pxelinux.0"
>           Vendor-rfc1048 Extensions
>             Magic Cookie 0x63825363
>             DHCP-Message Option 53, length 1: ACK
>             Server-ID Option 54, length 4: 10.14.80.6
>             Lease-Time Option 51, length 4: 10
>             Subnet-Mask Option 1, length 4: 255.255.255.0
>             Default-Gateway Option 3, length 4: 192.168.0.1
>             Domain-Name-Server Option 6, length 4: 192.168.0.4
>             Hostname Option 12, length 11: "lotus-19vm8"
>             Domain-Name Option 15, length 13: "subdomain.example.com"
>
> That particular client is defined later in the configuration file as:
>
>     host lotus-19vm8 {
>         hardware ethernet 52:54:00:19:D9:08;
>         filename "/pxelinux.0";
>         next-server 10.14.80.6;
>         option host-name="lotus-19vm8";
>         ddns-updates on;
>         ddns-hostname "lotus-19vm8";
>         ddns-domainname "subdomain.example.com";
>     }
>
> So why is the server sending the options from the wrong subnet
> declaration?  Certainly it would be more clear if both the address and
> options being offered were from the wrong subnet declaration but it
> seems odd that the server would be giving an address from one subnet
> declaration and options from the other.
>
> Ultimately what I am trying to achieve here is assigning
> "fixed-address"es for the first subnet and dynamic addresses for the
> second subnet where I have host declarations for all of my hosts and the
> dynamic ones look like the above and the fixed ones look like:
>
>     host lotus-6-mgmt {
>         hardware ethernet 00:e1:76:d6:12:06;
>         fixed-address 192.168.0.6;
>         option routers 10.14.80.1;
>         filename "/pxelinux.0";
>         next-server 10.14.80.6;
>         option host-name="lotus-6-mgmt";
>         ddns-updates on;
>         ddns-hostname "lotus-6-mgmt";
>         ddns-domainname "subdomain.example.com";
>     }
>
> Cheers,
> b.
>
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