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Hi I have a physical server running CentOS 7.3 with one interface connected to the Internet eno1(with one public IP address 217.33.44.17). I also have a block of IPs I would like to add so when i create a guest OS it will grab one of the public IPs (195.131.48.42 - 195.131.48.46 Usable).

I have been trying to get this to work for days now and am struggling i can set the machine to have the ip 195.131.48.42 and the machines work using the bridge but I would lose an IP.

Is there any guide available on how to do this any help be greatly appreciated and thanks in advance.

  • What hosting provider do you use? – Egor Vasilyev Sep 21 '17 at 8:00
  • The server is with seflow.net – David Sep 21 '17 at 11:23
  • What do you use in order to manage kvm ? virsh ? virt-manager ? – Pierre-Alain TORET Sep 21 '17 at 13:45
  • we use Virsh to manage the KVM – David Sep 21 '17 at 13:52
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First: Can you ping gateway address from your host?

# ping 195.131.48.41
PING 195.131.48.41 (195.131.48.41) 56(84) bytes of data.
64 bytes from 195.131.48.41: icmp_seq=1 ttl=57 time=1.41 ms
64 bytes from 195.131.48.41: icmp_seq=2 ttl=57 time=1.31 ms
64 bytes from 195.131.48.41: icmp_seq=3 ttl=57 time=1.34 ms
^C
--- 195.131.48.41 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 1.317/1.358/1.411/0.039 ms

I can normally.

Second: I can ping each address from your pool. Is it normal? Are you sure than you own this addresses?

64 bytes from 195.131.48.42: icmp_seq=1 ttl=57 time=1.27 ms
64 bytes from 195.131.48.43: icmp_seq=1 ttl=57 time=1.60 ms
64 bytes from 195.131.48.44: icmp_seq=2 ttl=57 time=1.31 ms
64 bytes from 195.131.48.45: icmp_seq=1 ttl=57 time=1.38 ms
64 bytes from 195.131.48.46: icmp_seq=1 ttl=57 time=1.32 ms

Third: I guess that for each ip addresses there is a corresponding mac. You need to request pair ip-mac from your provider. Usually you can do this in admin panel.

After this you need to change virtual machine configuration. You can do this with:

virsh edit vm_name

If you create new vm with virt-install define mac param (example does not contain a complete set of parameters):

virt-install --name vm_name \
             --network bridge=kvmbr0,model=virtio,mac=00:00:00:00:00:00 \
             ...

Last: i think you'll get more information about your problem from hosting provider technical support.

  • Perfect thanks needed the mac from the host providers – David Oct 4 '17 at 12:53
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What device has your router address (guessing .41)? If not the host, then the guest will need a path through the host to reach the router - eating up one of your 5 remaining public IPs.

  • Thanks for your reply yes the router is on 41. Im not sure how to create the route would you be able to point me to a tutorial on how to do this please. Many Thanks – David Sep 21 '17 at 0:00
  • I would suggest configuring your router as a bridge, and giving the host your router IP. Then your guests can see the router directly, and it's just a matter of setting your gateway address on the guests. – Soruk Sep 21 '17 at 0:02
  • This is what i have – David Sep 21 '17 at 0:05
  • Unfortunatly I dont have access to the router as this is in a hosting enviroment so this wouldnt be a option – David Sep 21 '17 at 0:11

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