Re: [Dnsmasq-discuss] Use dnsmasq to assign static /32 addresses via DHCP
Am 15.03.19 um 16:02 schrieb Simon Kelley: > On 15/03/2019 12:44, Peter Lieven wrote: >> Hi Simon, >> >> Am 14.03.19 um 18:41 schrieb Simon Kelley: >>> Is this a use for something like the ISC dhcpd shared-network configuration. >>> >>> >>> In the dnsmasq case, we could have something like >>> >>> shared-network=, >>> >>> or >>> >>> shared-network=, >>> >>> In the first case dnsmasq would behave _as_if_ the specified interface >>> carried the address and netmask specified. >>> >>> In the second case, it would behave as if the interface which carries >>> interface-address also carried the address and netmask specified. >>> >>> If I've understood correctly, you'd just need a shared-network >>> declaration for each of your /24s. >> >> What you describe is exactly what I would need. However, as far >> >> as I understand the documentation of the shared network feature in ISC dhcpd >> >> they still require that the network is configured on the DHCP interface (as >> alias, secondary etc.). >> >> This already works in dnsmasqd. I would need the feature that does not >> >> require the addresses to be actually configured on the interface as you >> >> describe it. >> > > I may have miss-understood the dhcpd case - what it does or doesn't do > is probably irrelevant to what dnsmasq can do in this case. > > > As far as I can see, there's no reason why it shouldn't work, with the > following caveats. > > 1) The DHCP server interface must have at least one address configured, > and that address needs to be reachable from configured clients. This > address gets used as the "server identifier" field in unicast > transmissions from the client to the server for things like lease > renewal. The case that the server-id is not on the same network as the > client is not new, it's the case when using a DHCP relay. Thats totally fine and its already the case today. The GW is a virtual address on the DHCP Interface. > > 2) Dnsmasq currently guesses at the default router to send to a client, > unless it's overridden by configuration. This is either its own address > on the network where the client is given an address, or, if the DHCP > came via relay, then it's the address of the relay on the network where > the client is given an address. In the case that a client is being given > an address on a network where neither the DHCP server or the DHCP relay > have an address, there's no sensible guess for what the client's default > router should be set to, so explicit configuration will have to be > mandatory. Thats also okay. The Router is reachable via a classless static route as the virtual GW is not part of the network. Most modern DHCP clients support this even without the classless static route option if the netmask is 255.255.255.255. Thats the common scenario e.g. in cable networks where each client gets a /32 IPv4 address as well. Best, Peter ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] Use dnsmasq to assign static /32 addresses via DHCP
On 15/03/2019 12:44, Peter Lieven wrote: > Hi Simon, > > Am 14.03.19 um 18:41 schrieb Simon Kelley: >> Is this a use for something like the ISC dhcpd shared-network configuration. >> >> >> In the dnsmasq case, we could have something like >> >> shared-network=, >> >> or >> >> shared-network=, >> >> In the first case dnsmasq would behave _as_if_ the specified interface >> carried the address and netmask specified. >> >> In the second case, it would behave as if the interface which carries >> interface-address also carried the address and netmask specified. >> >> If I've understood correctly, you'd just need a shared-network >> declaration for each of your /24s. > > > What you describe is exactly what I would need. However, as far > > as I understand the documentation of the shared network feature in ISC dhcpd > > they still require that the network is configured on the DHCP interface (as > alias, secondary etc.). > > This already works in dnsmasqd. I would need the feature that does not > > require the addresses to be actually configured on the interface as you > > describe it. > I may have miss-understood the dhcpd case - what it does or doesn't do is probably irrelevant to what dnsmasq can do in this case. As far as I can see, there's no reason why it shouldn't work, with the following caveats. 1) The DHCP server interface must have at least one address configured, and that address needs to be reachable from configured clients. This address gets used as the "server identifier" field in unicast transmissions from the client to the server for things like lease renewal. The case that the server-id is not on the same network as the client is not new, it's the case when using a DHCP relay. 2) Dnsmasq currently guesses at the default router to send to a client, unless it's overridden by configuration. This is either its own address on the network where the client is given an address, or, if the DHCP came via relay, then it's the address of the relay on the network where the client is given an address. In the case that a client is being given an address on a network where neither the DHCP server or the DHCP relay have an address, there's no sensible guess for what the client's default router should be set to, so explicit configuration will have to be mandatory. Cheers, Simon. ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] Use dnsmasq to assign static /32 addresses via DHCP
Hi Simon, Am 14.03.19 um 18:41 schrieb Simon Kelley: > Is this a use for something like the ISC dhcpd shared-network configuration. > > > In the dnsmasq case, we could have something like > > shared-network=, > > or > > shared-network=, > > In the first case dnsmasq would behave _as_if_ the specified interface > carried the address and netmask specified. > > In the second case, it would behave as if the interface which carries > interface-address also carried the address and netmask specified. > > If I've understood correctly, you'd just need a shared-network > declaration for each of your /24s. What you describe is exactly what I would need. However, as far as I understand the documentation of the shared network feature in ISC dhcpd they still require that the network is configured on the DHCP interface (as alias, secondary etc.). This already works in dnsmasqd. I would need the feature that does not require the addresses to be actually configured on the interface as you describe it. > > > > For the avoidance of doubt, this is NOT currently implemented on > dnsmasq, but it has been on the "desirable" list in my head for some time. I would like to help you implementing this, but unfortunately I am not at all familiar with the dnsmasq code (yet). I do not know how complicated it is to implement this, but I can at least help testing. Best, Peter ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] Use dnsmasq to assign static /32 addresses via DHCP
Is this a use for something like the ISC dhcpd shared-network configuration. In the dnsmasq case, we could have something like shared-network=, or shared-network=, In the first case dnsmasq would behave _as_if_ the specified interface carried the address and netmask specified. In the second case, it would behave as if the interface which carries interface-address also carried the address and netmask specified. If I've understood correctly, you'd just need a shared-network declaration for each of your /24s. For the avoidance of doubt, this is NOT currently implemented on dnsmasq, but it has been on the "desirable" list in my head for some time. Simon. On 12/03/2019 11:56, Peter Lieven wrote: > Hi, > > we run several thousand virtual gateways which are used to assign /32 > allocations to Virtual Servers via DHCP. > > > This so far runs pretty well except for one hack that we had to make and > that I would like to avoid. > > We assign the /32 networks out of /24 blocks that we reserved for this > purpose. However, dnsmasq only > assigns IP addresses via an interface if the network is configured on > that interface. We had to add some > more specific routes on the gateways to make a 2 hosts that receive a > /32 out of the same /24 see each > other if they are on different gateways. In fact I would like to > configure only one common virtual address > on the vserver facing interface lets say 10.255.255.255/32. > > What I would like to need is an option to either make dnsmasq assign > addresses out of an dhcp-range even > if the network is not configured on the dhcp interface or an option > where dnsmasq runs in a mode where it > > does not require dhcp-range options, but only works using dhcp-host > entries and replies if gets a request > > for a static mac address entry. > > > My config looks basically like this: > > [virtual gw1] > > dhcp-range=set:virtualgw,10.0.0.2,10.0.0.254,infinite,static > > dhcp-host=52:54:00:00:00:01,10.0.0.2,vserver1 > > dhcp-option=tag:virtualgw,1,255.255.255.255 > dhcp-option=tag:virtualgw,3,10.255.255.255 > dhcp-option=tag:virtualgw,28,255.255.255.255 > > dhcp-option=tag:virtualgw,121,10.255.255.255/32,0.0.0.0,0.0.0.0/0,10.255.255.255 > > > > [virtual gw2] > > dhcp-range=set:virtualgw,10.0.0.2,10.0.0.254,infinite,static > > dhcp-host=52:54:00:00:00:02,10.0.0.3,vserver1 > > dhcp-option=tag:virtualgw,1,255.255.255.255 > dhcp-option=tag:virtualgw,3,10.255.255.255 > dhcp-option=tag:virtualgw,28,255.255.255.255 > > dhcp-option=tag:virtualgw,121,10.255.255.255/32,0.0.0.0,0.0.0.0/0,10.255.255.255 > > > > To make dnsmasq deliver addresses out of 10.0.0.0/24 I have to configure > 10.0.0.1/24 > > on the DHCP interface. To ensure reachability between 10.0.0.2 and > 10.0.0.3 I have > > configured static routes 10.0.0.0/25 and 10.0.0.128/25 towards the > default gw. > > The configuration of 10.0.0.1/24 on the DHCP interface and the static > routes is what I would like to avoid. > > > Thanks for your feedback, > > Peter > > > > > ___ > 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
[Dnsmasq-discuss] Use dnsmasq to assign static /32 addresses via DHCP
Hi, we run several thousand virtual gateways which are used to assign /32 allocations to Virtual Servers via DHCP. This so far runs pretty well except for one hack that we had to make and that I would like to avoid. We assign the /32 networks out of /24 blocks that we reserved for this purpose. However, dnsmasq only assigns IP addresses via an interface if the network is configured on that interface. We had to add some more specific routes on the gateways to make a 2 hosts that receive a /32 out of the same /24 see each other if they are on different gateways. In fact I would like to configure only one common virtual address on the vserver facing interface lets say 10.255.255.255/32. What I would like to need is an option to either make dnsmasq assign addresses out of an dhcp-range even if the network is not configured on the dhcp interface or an option where dnsmasq runs in a mode where it does not require dhcp-range options, but only works using dhcp-host entries and replies if gets a request for a static mac address entry. My config looks basically like this: [virtual gw1] dhcp-range=set:virtualgw,10.0.0.2,10.0.0.254,infinite,static dhcp-host=52:54:00:00:00:01,10.0.0.2,vserver1 dhcp-option=tag:virtualgw,1,255.255.255.255 dhcp-option=tag:virtualgw,3,10.255.255.255 dhcp-option=tag:virtualgw,28,255.255.255.255 dhcp-option=tag:virtualgw,121,10.255.255.255/32,0.0.0.0,0.0.0.0/0,10.255.255.255 [virtual gw2] dhcp-range=set:virtualgw,10.0.0.2,10.0.0.254,infinite,static dhcp-host=52:54:00:00:00:02,10.0.0.3,vserver1 dhcp-option=tag:virtualgw,1,255.255.255.255 dhcp-option=tag:virtualgw,3,10.255.255.255 dhcp-option=tag:virtualgw,28,255.255.255.255 dhcp-option=tag:virtualgw,121,10.255.255.255/32,0.0.0.0,0.0.0.0/0,10.255.255.255 To make dnsmasq deliver addresses out of 10.0.0.0/24 I have to configure 10.0.0.1/24 on the DHCP interface. To ensure reachability between 10.0.0.2 and 10.0.0.3 I have configured static routes 10.0.0.0/25 and 10.0.0.128/25 towards the default gw. The configuration of 10.0.0.1/24 on the DHCP interface and the static routes is what I would like to avoid. Thanks for your feedback, Peter ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
