Re: dhcpd doesn't acknowledge dhcp requests

Posted by dave c on Jun 03, 2015; 3:33pm
URL: http://isc-dhcp-users.193.s1.nabble.com/dhcpd-doesn-t-acknowledge-dhcp-requests-tp124p134.html

Sean,

I don't see a subnet defined for the 10.64.0.104 local subnet.

Without it, broadcasts aren't going to get answered as there is no dhcpd pool or configuration
telling it to answer local requests.

Alternatively, if you wanted the devices to use an IP Helper, as long as the request comes from
an IP address including in one of your subnets, it will get linked to that network and if rules
are passed allowing an answer, you will get your dhcp answer at the remote device.

Try adding something like the following:

subnet 10.64.0.0 netmask 255.255.255.0 {  # obviously if this isn't a /24, then adjust as needed
     authoritative;
     option routers 10.64.0.1;
     option subnet-mask 255.255.255.0;
     min-lease-time 14400;
     default-lease-time 14400;
     range 10.64.0.5 10.64.0.10;
}

Dave

On 6/3/15 10:10, Sean McMurray wrote:

> On 06/02/2015 03:40 PM, Graham Clinch wrote:
>>> I have a dhcp server that won't give out leases and doesn't acknowledge
>>> DHCPDISCOVERs.
>>>
>>> I see the requests come in with tcpdump, but the daemon doesn't log them
>>> and doesn't respond.
>>>
>>> [snip]
>>>
>>>   >ss -anlp | grep ':67'
>>> tcp    UNCONN     0      0 *:67                    *:*
>>> users:(("dhcpd",21614,9))
>> Is the daemon listening on interface em2?
>>
>> # ss -anp | grep dhcpd
>> p_raw  UNCONN     0      0                      *:eth0                   *
>> users:(("dhcpd",24985,5))
>> [...]
>>
>> Alternatively, running the daemon manually in debug mode (-d) should give some hints as to the
>> interfaces it's discovered:
>>
>> Listening on LPF/eth0/00:14:22:28:ad:83/192.168.125.0/24
>> Sending on   LPF/eth0/00:14:22:28:ad:83/192.168.125.0/24
>> Sending on   Socket/fallback/fallback-net
> On startup it says that it is Listening and Sending on em2. It also lists interfaces it will
> ignore because there is no matching subnet declared in dhcpd.conf.
>
> It also says:
>
>      Sending on   Socket/fallback/fallback-net
>
>> ss -anp | grep dhcpd
> p_raw  UNCONN     0      0                      *:em2                  *
> users:(("dhcpd",21614,5))
> u_str  ESTAB      0      0                      * 558943                 * 559749
> users:(("dhcpd",21614,2),("dhcpd",21614,1))
> u_dgr  UNCONN     0      0                      * 558954                 * 8044
> users:(("dhcpd",21614,3))
> raw    UNCONN     0      0                      *:1                     *:*
> users:(("dhcpd",21614,4))
> tcp    UNCONN     0      0                      *:14659                 *:*
> users:(("dhcpd",21614,20))
> tcp    UNCONN     0      0                      *:67                    *:*
> users:(("dhcpd",21614,9))
> tcp    UNCONN     0      0                     :::23465                :::*
> users:(("dhcpd",21614,21))
> tcp    LISTEN     0      1            10.64.0.104:647                   *:*
> users:(("dhcpd",21614,11))
> tcp    ESTAB      0      0            10.64.0.104:647         10.64.0.112:56061
> users:(("dhcpd",21614,10))
>
>
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--
Dave Calafrancesco
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