DHCPNAK reply using wrong server identifier IP

[Vic Berdin]

Hi Glenn (and everyone),

> Message: 2
> Date: Thu, 26 May 2011 17:51:49 +1000
> From: "Glenn Satchell" <glenn.satchell at uniq.com.au>
> Subject: Re: DHCPNAK reply using wrong server identifier IP
> To: "Users of ISC DHCP" <dhcp-users at lists.isc.org>
> Message-ID:
>	<1bdfb29939ff305cb0643cd612bdfa22.squirrel at mail.uniq.com.au>
> Content-Type: text/plain;charset=iso-8859-1
>
> dhcp-server-identifier sets the IP inside the internal dhcp option space,
> not the source IP address on the packet.

Thanks for your reply. Please check out the Wire Shark screen capture I have
included on this e-mail. "eth0: 192.168.1.111" and "eth0:0: 192.168.1.110"
are the same DHCP server box. Notice that DHCPACKs and DHCPOFFERs have the
correct server identifier as declared in my /etc/dhcpd.conf below. Only
DHCPNAKs have the wrong server identifier.

Here is my complete /etc/dhcpd.conf listing:

-----
max-lease-time 1209600;
ddns-update-style none;
authoritative;
server-name "deli1";
option dhcp-server-identifier 192.168.1.110;

subnet 192.168.1.0 netmask 255.255.255.0 {
    filename "//tvp1500.txt";
    option routers 192.168.1.1;
    range 192.168.1.5 192.168.1.140;
    }
host client0 {
    hardware ethernet 00:60:03:04:31:B8;
    fixed-address 192.168.1.151;
    filename "//tvp1500.txt";
    option routers 192.168.1.1;
    }
host client1 {
    hardware ethernet 00:60:03:02:F1:38;
    fixed-address 192.168.1.152;
    filename "//tvp1500.txt";
    option routers 192.168.1.1;
    }
host client2 {
    hardware ethernet 00:60:03:04:31:B3;
    fixed-address 192.168.1.153;
    filename "//tvp1500.txt";
    option routers 192.168.1.1;
    }
host client3 {
    hardware ethernet 00:60:03:04:84:4C;
    fixed-address 192.168.1.154;
    filename "//tvp1500.txt";
    option routers 192.168.1.1;
    }
host client3 {
    hardware ethernet 00:60:03:03:7F:92;
    fixed-address 192.168.1.155;
    filename "//tvp1500.txt";
    option routers 192.168.1.1;
    }
-----

Does DHCPD refer to some other system network file like the /etc/hosts list?
Because only eth0: 192.168.1.111 is listed in my /etc/hosts list file: 

-----
root % cat /etc/hosts
127.0.0.1 localhost
192.168.1.111 deli1.boracay.ph deli1
192.168.1.111 my_eth0_ip
192.168.1.112 deli2
192.168.2.2 dg_pgpl_bck
-----

root % dhcpd --version
isc-dhcpd-4.2.1
-----


Any info is very much welcome. I will also try having 'server-identifier
192.168.1.110' directives inside each of my 'subnet' and 'host'
sub-settings/clause even if I don't see any reason why I should do this.



Thanks and best regards,
Vic

------------------------------

Message: 2
Date: Thu, 26 May 2011 17:51:49 +1000
From: "Glenn Satchell" <glenn.satchell at uniq.com.au>
Subject: Re: DHCPNAK reply using wrong server identifier IP
To: "Users of ISC DHCP" <dhcp-users at lists.isc.org>
Message-ID:
	<1bdfb29939ff305cb0643cd612bdfa22.squirrel at mail.uniq.com.au>
Content-Type: text/plain;charset=iso-8859-1

dhcp-server-identifier sets the IP inside the internal dhcp option space,
not the source IP address on the packet.

regards,
-glenn

> Hi ISC-DHCP-Users,
>
>
>
> I have configured dhcpd.conf to use an global 'option
> dhcp-server-identifier
> xxx.xxx.xxx.xxx' directive since my server box has more than one IP
> (raised
> on an alias device). This 'dhcp-server-identifier IP' is actually an alias
> IP via eth0:0.
>
> Now, after playing with Wire Shark, I noticed that each time the server
> issues a DHCPNAK reply (due to a client DHCPREQUEST for a wrong IP), the
> DHCPNAK is being sent thru the real IP in eth0, and not thru the
> configured
> 'option dhcp-server-identifier IP' eth0:0 IP.
>
> My questions now are:
>
> 1. Is there a specific reason why DHCPNAK replies do not follow the global
> 'option dhcp-server-identifier xxx.xxx.xxx.xxx' directive?
> 2. Should I use a 'server-identifier IP' sub-directive ('tho I haven't
> tried
> yet) instead of a global one?
>
> Any tips/explanations are very much welcome.
>
>
> Best regards,
> Vic
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