Re: [Dnsmasq-discuss] Overlapping/duplicate subnets
Hi, While it might seem weird, it is a valid scenario. There might be reasons to let reusing IP addresses. To answer your question about deployment of NAT devices, it shouldn't be just a NAT device. Each LAN segment can have its own NAT gateway. Regards, On Wed, Feb 22, 2017 at 4:07 PM, /dev/rob0wrote: > On Wed, Feb 22, 2017 at 02:55:30PM +0100, S. M. Hossein Hamidi wrote: > > I am new to dnsmasq and my mind is busy with a DHCP scenario that I > > would like to consult with you before getting my hands dirty. > > > > Suppose that we have several subnets which are behind a NAT device > > which additionally acts as a DHCP relay agent. I know that using > > DHCP relay agent information option, I can distinguish between > > different subnets. However, the additional constraint is to use > > duplicate or overlapping subnets instead of distinct subnets. > > That is a very strange constraint. RFC 1918 is quite large enough; > it's not necessary to share your netblocks. And how will your NAT > device distinguish one segment with a shared netblock from another > segment using the same netblock? > > Sounds like broken IP networking to me. Compliant IP stacks do > routing based on IP address blocks. > > > Since, the traffic comes from each segment goes through NAT, it > > wouldn't be any problem to use duplicate IP addresses, knowing > > that each segment has its own autonomy. > > But again, how does the NAT device do this? > > > So, may I know if can I exploit tagging feature of dnsmasq so > > that it can handle separate potentially overlapping leases for > > each subnet? > > I'm pretty sure this would not be possible in dnsmasq nor in ISC > dhcpd. Either one could do a single netblock shared among many > distinct segments, but each would only be able to give out any one > address to only one client. > > But wait and see what Simon says. :) > -- > http://rob0.nodns4.us/ > Offlist GMX mail is seen only if "/dev/rob0" is in the Subject: > > ___ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.thekelleys.org.uk > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss > ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] Overlapping/duplicate subnets
On Wed, Feb 22, 2017 at 02:55:30PM +0100, S. M. Hossein Hamidi wrote: > I am new to dnsmasq and my mind is busy with a DHCP scenario that I > would like to consult with you before getting my hands dirty. > > Suppose that we have several subnets which are behind a NAT device > which additionally acts as a DHCP relay agent. I know that using > DHCP relay agent information option, I can distinguish between > different subnets. However, the additional constraint is to use > duplicate or overlapping subnets instead of distinct subnets. That is a very strange constraint. RFC 1918 is quite large enough; it's not necessary to share your netblocks. And how will your NAT device distinguish one segment with a shared netblock from another segment using the same netblock? Sounds like broken IP networking to me. Compliant IP stacks do routing based on IP address blocks. > Since, the traffic comes from each segment goes through NAT, it > wouldn't be any problem to use duplicate IP addresses, knowing > that each segment has its own autonomy. But again, how does the NAT device do this? > So, may I know if can I exploit tagging feature of dnsmasq so > that it can handle separate potentially overlapping leases for > each subnet? I'm pretty sure this would not be possible in dnsmasq nor in ISC dhcpd. Either one could do a single netblock shared among many distinct segments, but each would only be able to give out any one address to only one client. But wait and see what Simon says. :) -- http://rob0.nodns4.us/ Offlist GMX mail is seen only if "/dev/rob0" is in the Subject: ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
[Dnsmasq-discuss] Overlapping/duplicate subnets
Hi all, I am new to dnsmasq and my mind is busy with a DHCP scenario that I would like to consult with you before getting my hands dirty. Suppose that we have several subnets which are behind a NAT device which additionally acts as a DHCP relay agent. I know that using DHCP relay agent information option, I can distinguish between different subnets. However, the additional constraint is to use duplicate or overlapping subnets instead of distinct subnets. Since, the traffic comes from each segment goes through NAT, it wouldn't be any problem to use duplicate IP addresses, knowing that each segment has its own autonomy. So, may I know if can I exploit tagging feature of dnsmasq so that it can handle separate potentially overlapping leases for each subnet? Regards, ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss