[Dnsmasq-discuss] dnsmasq configuration

richardvoigt at gmail.com richardvoigt at gmail.com
Tue Dec 4 20:47:47 GMT 2012


On Tue, Dec 4, 2012 at 3:24 PM, Lovelady, Dennis E. <dlovelady1 at dtcc.com>wrote:

>  Isn’t routing ignored when the destination is on the local net?  Would
> this really cause a loop?  If so, wouldn’t routing be impossible, since any
> attempt to route anything has to result in the same loop?  Or don’t I
> understand the problem?****
>
> **
>

Normally there's a route automatically created for the local net, which may
have a special local flag or list the host's own local interface address as
the gateway, triggering the end of routing lookup.  But the OP mentioned a
setup that uses a different gateway for the same local net.

(You might even say that the presence of such a terminal routing rule is
what makes that net local, not the subnet mask.  Consider VPN connections,
where other hosts in the same subnet according to the mask test still are
not local.  A VPN implementation might add a rule making the VPN peer
local, and another rule making the subnet reachable using the VPN peer as
gateway.  Communications in the opposite direction generally works because
of proxy ARP.)

Have a look at your routing table.  I think you'll find an
automatically-generated route for the local subnet.



> **
>
>  ****
>
> *From:* dnsmasq-discuss-bounces at lists.thekelleys.org.uk [mailto:
> dnsmasq-discuss-bounces at lists.thekelleys.org.uk] *On Behalf Of *
> richardvoigt at gmail.com
> *Sent:* Tuesday, December 04, 2012 3:20 PM
> *To:* Ritesh Nanda
> *Cc:* dnsmasq discussion list
> *Subject:* Re: [Dnsmasq-discuss] dnsmasq configuration****
>
> ** **
>
> ** **
>
> ** **
>
> On Thu, Nov 29, 2012 at 8:31 AM, Ritesh Nanda <riteshnanda09 at gmail.com>
> wrote:****
>
> hello,
>
> I am working on openstack , which uses dnsmasq as a dhcp server.
> Here is a challenge what i am facing , using dnsmasq configuration file i
> am adding a default route to the vms that are created in this
> enviornment, now challenge i am facing is i want to add two routes using
> dnsmasq configuration file.
>
> one route for a particular subnet so that it request  get forwared to a
> gateway
> and one as a default route.
> eg.
>
> 192.168.10.0 network request gets forwarded to gateway 192.168.10.6
> and all other request gets forwarded to 192.168.10.1****
>
> ** **
>
> You may have some trouble implementing this particular routing table,
> because requests to 192.168.10.* are routed to 192.168.10.6, which is in
> 192.168.10.*, so it's reached via 192.168.10.6, which is in 192.168.10.*,
> and ad infinitum.****
>
> ** **
>
> The gateway address specified in the routing table should be on the local
> network, not the network the gateway is used to reach (this implies that
> every gateway should be multi-homed).****
>
> ** **
>
>  ****
>
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