Requests on Second NIC

[Glenn Satchell]

>X-Original-To: dhcp-users at webster.isc.org
>To: dhcp-users at isc.org
>Subject: Re: Requests on Second NIC
>From: Rimike Y Liverpool <ryliverp at us.ibm.com>
>Date: Tue, 30 May 2006 08:38:31 -0500
>
>I am only using en1 on subnet 192.168.0.x but I can see requests from the 
>subnet that en0 is on, a.b.c.x
>So I see :
>May 30 08:27:32 HOSTNAME dhcpd: DHCPREQUEST for a.b.c.x (a.b.d.y) from 
>aa:bb:cc:dd:ee:ff via en1: wrong network.

The traffic is coming in via en1, so dhcpd and this computer are "doing
the right thing".

I can think of three possibilities:

1. The computer with mac address aa:bb:cc:dd:ee:ff used to be on the
a.b.c.x network and has now moved to the 192.168.0.x network and is
asking for its old address again.

2. There is some sort of routing loop and packets from the wrong
network are somehow making to en1 when they shouldn't be.

3. Your dhcpd.conf does not represent the true way the networks are
setup.

If you use a packet tracing program (eg ethereal, tcpdump, snoop, etc)
and listen on en1 do you see the packets? Do they in fact have the
wrong source or destination IP address?

regards,
-glenn

>For what I  have right now, the clients that are on the 192.168.0 network 
>do not move around.
>
>Thanks
>
>.Yema Liverpool
>AIX  Support Team-Rochester, MN
>Integrated Technology Delivery, Server Operations 
>Dept LVJG, Bldg 020-3 A224
>Phone:  507-253-5817
>ryliverp at us.ibm.com
>
>
>
>Simon Hobson <dhcp at thehobsons.co.uk> 
>Sent by: dhcp-users-bounce at isc.org
>05/25/2006 05:24 PM
>Please respond to
>dhcp-users at isc.org
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>
>To
>dhcp-users at isc.org
>cc
>
>Subject
>Re: Requests on Second NIC
>
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>Rimike Y Liverpool wrote:
>
>>When I look at the logs, I see the requests from the other network.
>>Granted, they get NACKs with a message saying "wrong network" but I was
>>wondering if it would be possible not to even get those.
>
> From the wrong subnet, or from the wrong physical network ?
>
>For example, assuming you are only using eth1 and a.b.c.x is the 
>subnet on eth0 ...
>
>If you see "blah DHCPREQUEST for a.b.c.123 from aa:bb:cc:dd:ee:ff 
>(xyz) via eth0"
>then there is a problem and you are getting packets from the wrong 
>physical network
>
>However, if you see "blah DHCPREQUEST for a.b.c.123 from 
>aa:bb:cc:dd:ee:ff (xyz) via eth1"
>then you need to figure out why requests are coming in for the wrong 
>subnet on the right interface.
>
>Do you have clients that move around ? If a client moves from one 
>network to the other you would expect to see the requests with wrong 
>network as the client attempts to renew it's previous lease.
>
>Simon
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