[libvirt-users] IPv4 routed virtual networks
OK, either I have taken a stupid pill and am missing something basic or routed network do not work. I assume that, if they did work, it would be in more or less that same manner as a nat network as far as ping'ing, ssh'ing, etc. to another real host on the same real LAN as the virtualization host. At least that is what I believe I should expect. I have googled for info and everything says that it should work. On of the referenced documents was this: http://berrange.com/posts/2009/12/13/routed-subnets-without-nat-for-libvirt-... I checked through everything and it all matches what is in the document. I can go from the guest to the host (ping, ssh, etc) but not from that guest to another real host on the same real LAN. I am patching the relevant info below: ---------------------------------- net.ipv4.conf.all.forwarding = 1 net.ipv4.conf.p32p1.forwarding = 1 net.ipv4.conf.virbr8.forwarding = 1 -------------------------------- <network> <name>routed</name> <uuid>1b2a0197-e708-165c-f266-6822e73cfbdd</uuid> <forward dev='p32p1' mode='route'> <interface dev='p32p1'/> </forward> <bridge name='virbr8' stp='on' delay='0' /> <mac address='52:54:00:B9:59:49'/> <domain name='routed'/> <ip address='192.168.123.1' netmask='255.255.255.0'> <dhcp> <range start='192.168.123.128' end='192.168.123.254' /> </dhcp> </ip> </network> ------------------------------- Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 0 0 ACCEPT udp -- virbr8 * 0.0.0.0/0 0.0.0.0/0 udp dpt:53 0 0 ACCEPT tcp -- virbr8 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 0 0 ACCEPT udp -- virbr8 * 0.0.0.0/0 0.0.0.0/0 udp dpt:67 0 0 ACCEPT tcp -- virbr8 * 0.0.0.0/0 0.0.0.0/0 tcp dpt:67 Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 0 0 ACCEPT all -- p32p1 virbr8 0.0.0.0/0 192.168.123.0/24 0 0 ACCEPT all -- virbr8 p32p1 192.168.123.0/24 0.0.0.0/0 0 0 ACCEPT all -- virbr8 virbr8 0.0.0.0/0 0.0.0.0/0 0 0 REJECT all -- * virbr8 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable 0 0 REJECT all -- virbr8 * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable ------------------------------ This is Fedora 17 with an updated libvirt 0.10.1-4.fc17 [another system with the same "problem" is running libvirt 0.10.2-1.fc17]. Anyone know what is going on? BTW, I searched bugzilla for the comment containing the string routed filed against packages libvirt, qemu, qemu-kvm, or kvm ...Result .. no hits! If this is really a bug rather than something I did or did not do, then nobody is using routed virtual networks. BTW, I have a real F17 systems sitting between to networks on two different NICs and it routes things nicely, thank you very much. It does work but not for the virtual networks. I would really like it to be something I am missing. Gene
On 10/03/2012 10:08 PM, Gene Czarcinski wrote:
OK, either I have taken a stupid pill and am missing something basic or routed network do not work.
I assume that, if they did work, it would be in more or less that same manner as a nat network as far as ping'ing, ssh'ing, etc. to another real host on the same real LAN as the virtualization host. At least that is what I believe I should expect.
I use routed networks, but they require some extra work. The docs [1] say that "This is a variant on the default network which routes traffic from the virtual network to the LAN _without applying any NAT_. It requires that the IP address range be _pre-configured in the routing tables of the router on the host network_." (emphasis mine) The way I read into this is that you are responsible for routing packets yourself. The docs say that you have to use IP addresses that are visible by the host and external machines and configure your routing table, so that it forwards packets to the VMs. I am not sure how to do that, but I have a different solution -- I use a pair of IP addresses for each VM: external (real and configured on the host) and internal. Then I have a SNAT + DNAT pair of iptables rules that expose the VM to the outside world in a manner similar to the one used in DMZ setups: ubuntu@thehost:~$ sudo iptables -t nat -L -n Chain PREROUTING (policy ACCEPT) target prot opt source destination DNAT all -- 0.0.0.0/0 X.Y.Z.120 to:10.1.1.2 ... Chain POSTROUTING (policy ACCEPT) target prot opt source destination SNAT all -- 10.1.1.2 0.0.0.0/0 to:X.Y.Z.120 I am not sure if anyone else is doing the SNAT/DNAT thing to routed networks, but it's been working quite nicely for me so far. Best, Hristo [1] http://libvirt.org/formatnetwork.html#examplesRoute
participants (2)
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Gene Czarcinski -
Hristo Deshev