VMM connect problem -
Bob Goodwin
bobgoodwin at wildblue.net
Fri Mar 4 23:42:55 UTC 2016
On 03/04/16 18:01, Rick Stevens wrote:
> On 03/04/2016 01:38 PM, Bob Goodwin
> wrote:
>> I have two Fedora-23 computers
>> running virtual machine manager, this
>> one
>> connects to my ethernet LAN and
>> connects to the internet, the second
>> one, I've just set up connects to the
>> LAN but not the internet,
>> something is wrong with VMM
>> configuration.
>
> Are both of these machines you're
> talking about acting as hosts for
> virtual machines?
.
Both F23 boxes have vmm running in them.
The ifconfig data is from Centos7 in the
VM's rather than the host machine.
>
>>
>> This one, the working one shows:
>>
>> [bobg at localhost ~]$ ifconfig
>> eth0:
>> flags=4163<UP,BROADCAST,RUNNING,MULTICAST>
>> mtu 1500
>> inet 192.168.122.30 netmask
>> 255.255.255.0 broadcast
>> 192.168.122.255
>> inet6
>> fe80::5054:ff:fe65:23a6 prefixlen 64
>> scopeid 0x20<link>
>> ether 52:54:00:65:23:a6
>> txqueuelen 1000 (Ethernet)
>> RX packets 162 bytes 11984
>> (11.7 KiB)
>> RX errors 0 dropped 0
>> overruns 0 frame 0
>> TX packets 89 bytes 11226
>> (10.9 KiB)
>> TX errors 0 dropped 0
>> overruns 0 carrier 0 collisions 0
>
> That is an odd IP address to see on
> eth0 on a virtual machine _host_.
> I'd expect a virtual machine _guest_
> to have an eth0 address on that
> 192.168.122 network.
>
> 192.168.122 is typically used by the
> libvirt mechanism to provide IP
> addresses to virtual machines. libvirt
> runs a DHCP server offering IPs
> on the 192.168.122 network to the
> virtual machines running under it.
>
> Be that as it may, since the IP is on
> eth0, it's valid and your router
> is NATting it and allowing you out to
> the internet.
>
>>
>> lo: flags=73<UP,LOOPBACK,RUNNING>
>> mtu 65536
>> inet 127.0.0.1 netmask
>> 255.0.0.0
>> inet6 ::1 prefixlen 128
>> scopeid 0x10<host>
>> loop txqueuelen 0 (Local
>> Loopback)
>> RX packets 20 bytes 1716
>> (1.6 KiB)
>> RX errors 0 dropped 0
>> overruns 0 frame 0
>> TX packets 20 bytes 1716
>> (1.6 KiB)
>> TX errors 0 dropped 0
>> overruns 0 carrier 0 collisions 0
>>
>>
>> This is what I see in the other one
>> that does not connect:
>>
>> [bobg at localhost ~]$ ifconfig
>> eth0:
>> flags=4163<UP,BROADCAST,RUNNING,MULTICAST>
>> mtu 1500
>> ether 52:54:00:c8:72:84
>> txqueuelen 1000 (Ethernet)
>> RX packets 39 bytes 2028
>> (1.9 KiB)
>> RX errors 0 dropped 0
>> overruns 0 frame 0
>> TX packets 0 bytes 0 (0.0 B)
>> TX errors 0 dropped 0
>> overruns 0 carrier 0 collisions 0
>
> Note that eth0 does NOT have an IP
> address, so it can't do anything on
> the LAN (or the Internet).
.
Yes, I understand that, but after
following the prompts for installing the
centos system in the vm and VMM itself
this is what resulted and I don't know
what it is supposed to look like. All I
could do was compare the working with
the non working.
>
>> lo: flags=73<UP,LOOPBACK,RUNNING> mtu
>> 65536
>> inet 127.0.0.1 netmask
>> 255.0.0.0
>> inet6 ::1 prefixlen 128
>> scopeid 0x10<host>
>> loop txqueuelen 0 (Local
>> Loopback)
>> RX packets 128 bytes 11136
>> (10.8 KiB)
>> RX errors 0 dropped 0
>> overruns 0 frame 0
>> TX packets 128 bytes 11136
>> (10.8 KiB)
>> TX errors 0 dropped 0
>> overruns 0 carrier 0 collisions 0
>>
>> virbr0:
>> flags=4099<UP,BROADCAST,MULTICAST>
>> mtu 1500
>> inet 192.168.122.1 netmask
>> 255.255.255.0 broadcast
>> 192.168.122.255
>> ether 52:54:00:71:23:11
>> txqueuelen 0 (Ethernet)
>> RX packets 0 bytes 0 (0.0 B)
>> RX errors 0 dropped 0
>> overruns 0 frame 0
>> TX packets 0 bytes 0 (0.0 B)
>> TX errors 0 dropped 0
>> overruns 0 carrier 0 collisions 0
>
> virbr0 (virtual bridge zero) is
> created by libvirt and used to route
> traffic INSIDE that machine between
> itself and the virtual machines
> it's hosting. Note that it has the
> 192.168.122.1 address (typical of a
> VM host acting as a router for the
> virtual machines running under it)
> and _virtual_ machines running on that
> host it will have addresses on
> that 192.168.122 network applied to
> their eth0 interfaces (assuming
> they're configured to use DHCP to get
> an address).
>
>> [bobg at localhost ~]$ ping -c 3 8.8.8.8
>> connect: Network is unreachable
>>
>> I don't know what I might have done
>> differently on the seond VM install,
>> incidentally both are installed
>> usingthe same centos 7 iso if that is of
>> interest ...
>>
>> Any suggestion of what to do next
>> will be appreciated,
>
> Give an IP address to eth0 on the
> machine that's not working and/or
> leave it using DHCP and ensure you
> have a DHCP server on the network
> it's plugged into.
>
> Your network appears a bit weird to
> me. My LAN uses 192.168.1.0/24
> with 192.168.1.1 on the LAN side of my
> router (the WAN side of the router has
> a routable public IP). The router also
> has a DHCP server
> on it. I prefer to use fixed IPs for
> my non-mobile devices, so I have
> the DHCP server restricted to only
> offer addresses between 192.168.1.192
> and 192.168.1.254, letting me use
> 192.168.1.2 through .191 for fixed
> IPs.
>
> My first VM host (vmhost-a) has a
> fixed address of 192.168.1.10 on eth0
> (on the LAN). My second VM host
> (vmhost-b) has a fixed address of
> 192.168.1.15 on eth0 (also on the
> LAN). Both of them have default
> routes that specify 192.168.1.1 (the
> IP address of my router on the
> LAN).
>
> When libvirtd starts on both vmhost-a
> and vmhost-b, it creates a
> virbr0 interface on each and gives it
> an address of 192.168.122.1. The
> thing to note here is that even though
> both machines have the same
> address on virbr0, that network is
> only visible INSIDE the physical
> machine. This means the 192.168.122
> network on vmhost-a does not
> conflict with the 192.168.122 network
> on vmhost-b.
>
> If I start a VM on vmhost-b and that
> VM has its eth0 configured to use
> DHCP, it will get an address from the
> DHCP server running as part of
> libvirtd on vmhost-b. It will get an
> IP address of 192.168.122.x (we'll
> use .10 for an example) and a default
> gateway of 192.168.122.1.
>
> Now, if that VM sends traffic out, it
> will go through its simulated
> eth0 (192.168.122.10) and libvirtd
> will see it on its virbr0 at
> 192.168.122.1. libvirtd will then
> route the traffic out its eth0
> (192.168.1.15) and the router will
> pick that up off its 192.168.1.1
> interface and route it through to the
> internet. Replies go back down
> the same pipeline in reverse.
> Remember, the router sees the traffic
> as coming from vmhost-b, so replies go
> back to it. vmhost-b reroutes
> the reply traffic through its virbr0
> back to the VM.
>
> I hope my example clears it up a bit.
> There's a lot to absorb there.
Yes, everything helps. My LAN address
scheme is about the same as yours. I
think I will try assigning a fixed
address to the second box, if that works
I'll do the same on the one that is
working ...
I'll report the result tomorrow'
Thank you,
Bob
> ----------------------------------------------------------------------
>
> - Rick Stevens, Systems Engineer,
> AllDigital ricks at alldigital.com -
> - AIM/Skype: therps2 ICQ:
> 226437340 Yahoo: origrps2 -
> - -
> - I will go to my happy place. I
> WOULD go to my happy place.... -
> - if I knew where the
> @$>&$@#* it is! -
> ----------------------------------------------------------------------
>
--
Bob Goodwin - Zuni, Virginia, USA
http://www.qrz.com/db/W2BOD
box10 FEDORA-23/64bit LINUX XFCE POP3
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