Default Gateway via DHCP

[MAtteo HCE Valsasna]

Il giorno ven, 08/08/2008 alle 00.13 +0000, DHCP Users Mailing List ha
scritto:
> 
> David W. Hankins wrote:
> > On Thu, Aug 07, 2008 at 01:16:00PM -0700, Daniel L. Miller wrote:
> >   
> >> Below is an excerpt from my dhcpd.conf for version 3.  Nearly everything 
> >> is working correctly, but I've noticed the default gateway is not being 
> >> set correctly on my clients.  The gateway SHOULD be 192.168.0.72, but 
> >> the clients are showing 192.168.0.1.  

> I'm defining the "option routers" 
> >> at pool and group levels - I don't know why.
> >>     
> >
> > 192.168.0.1 doesn't appear anywhere in your config file, so I would
> > first suspect a second DHCP server.

I agree, also because 192.168.0 is one of the most commonly used
subnets.  

To rule this out, you may want to check who your clients think their
DHCP server was. 

In windows, do "ipconfig /all" and look for the DHCP server line; in
linux you may find a lease file in 
/var/lib/dhcp3/dhclient.eth0.leases or similar places, look for the
dhcp-server-identifier line.

> I don't have one.  

possibly someone connected one to your network, either inadvertently
(this may include funny things as a soho wireless router used as an AP,
but not configured to disable dhcp service, some laptop configured with
"internet connection sharing" for use at home, or the DHCP server
included in wmvare that for some reason is not configured to serve only
the virtual network between the host and guest OSs) or maliciously
(someone trying disrupt network operation or - worse - intercept your
client's traffic, sniff and relay it to the legitimate router)

switches with dhcp snooping may be very good friends to avoid this.

> It IS the default gateway based on standard IP 
> address schemes - I'm trying to override that.
> 
> I believe my dynamic clients are setting the gateway appropriately.  
> It's the statics that are giving me trouble.

they may not be inheriting the router setting from the group statement.
this may make sense, as static client are not necessarily bound to one
subnet, while address pools are. 
try setting the router at the subnet level, and overriding it only when
you need (openvpn clients)

MAtteo