First time relayed network

[Scott Ellentuch]

Hi,

Either I spoke too soon, or I didn't test well enough.

We had someone try to dhcp in the OTHER range in the shared network and we
got :

Apr  5 13:18:28 dhcp1 dhcpd: DHCPREQUEST for 10.9.18.215 (10.9.12.0) from
00:50:56:ac:d9:bf via eth0

(This is a different site, but same issues...)

It seems it was just giving out 10.9.18 IPs even though it seemed to know
it needed to give a 10.9.12.0 . Do I need to start doing something like

class newsubnet {
    match if option agent.link-selection = "10.9.18.1"
}

and put in the 10.9.12 pool

deny members of newsubnet;

and in 10.9.18

allow members of newsubnet;

?

Thanks, Tuc




On Fri, Mar 24, 2017 at 9:50 PM, Tuc at Beach House <tuctboh at gmail.com>
wrote:

> Hi,
>
> Thanks. Actually solved it this morning after piecing together help from a
> few people. Option 82 googling makes it FAR scarier than it needs to be. I
> also then started debugging source to figure out the problem with the
> "unknown network segment" to find out it was my misreading the correct
> subnet 205 times.
>
> Yes, it was actually as easy as adding a shared-network and putting the
> correct subnet. I didn't need to mess with agent.link-selection or anything!
>
> Thanks, Tuc
>
>
>
>
> On Fri, Mar 24, 2017 at 9:41 PM, Patrick Trapp <ptrapp at nex-tech.com>
> wrote:
>
>> When I see those in my logs, it is because the  request is coming from a
>> network the DHCP server is not addressing and it does not know what pool to
>> associate the request with. I create a shared-network statement including
>> the intended pool and the mystery network. Since I'm not providing an
>> address for the mystery network, the network statement (where i would
>> normally define the network) is a pair of empty braces.
>>
>> I hope that makes sense - I can provide example configs later, but not at
>> the moment. Hope it helps.
>>
>> Patrick
>>
>> > On Mar 24, 2017, at 7:51 PM, Tuc at Beach House <tuctboh at gmail.com>
>> wrote:
>> >
>> > Hi,
>> >
>> >
>> > I'm trying to figure out how to do relayed subnets within a datacenter
>> > owners environment and our (sorry, old) 4.1.1-38.P1 ISC DHCP server.
>> > Normally we allocated an interface to our machine for every subnet
>> > that its on, but this new network is "remote" and they won't stretch
>> > L2 to us.
>> >
>> > So the normal config isn't what I'm used to, but works :
>> >
>> >        subnet 10.14.14.0 netmask 255.255.255.0 {
>> >
>> >               interface eth0;
>> >                authoritative;
>> >                allow booting;
>> >                option routers                  10.14.14.1;
>> >                option subnet-mask              255.255.255.0;
>> >                option domain-name              "
>> cust19782.dc.example.com";
>> >                option domain-name-servers      10.14.2.1;
>> >                option ntp-servers              10.14.2.1;
>> >                next-server 10.14.14.11
>> >                filename "pxelinux.0";
>> >                pool {
>> >                        option routers                  10.14.14.1;
>> >                        option domain-name-servers 10.14.2.1;
>> >                        max-lease-time 600;
>> >                        range 10.14.14.200 10.14.14.254;
>> >                        allow unknown-clients;
>> >                }
>> >        }
>> >
>> >
>> > And the others all are the same, but with different "interface"
>> > statements. It is not wrapped in any sort of "shared-network"
>> > statement.
>> >
>> > I'm getting valid Option 82 information, so I did :
>> >
>> > class "EXTDHCP" {
>> > match if option agent.link-selection  = "10.14.18.0";
>> > }
>> >
>> > And then pretty much the same except removed the "interface"
>> > statement, and added "allow members of "EXTDHCP";" into the pool
>> > statement.
>> >
>> > However, all I keep seeing in my logs is :
>> >
>> > dhcpd: DHCPDISCOVER from 81:9c:de:3b:61:02 via 10.14.17.2: unknown
>> > network segment
>> >
>> > 10.14.17.2 is the TOR switch IP thats handling the relay. I can't seem
>> > to find any more in depth debug. Pointers to where I went wrong? (And
>> > "Using DHCPD 4.1.1" if it can't do it is acceptable)
>> >
>> >
>> > Thanks, Tuc
>> > _______________________________________________
>> > dhcp-users mailing list
>> > dhcp-users at lists.isc.org
>> > https://lists.isc.org/mailman/listinfo/dhcp-users
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>
>
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