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I am on Centos 7 with KVM and virt-manager installed. I have a virtual (guest) machine with Debian 8.1 on it. Network on guest was configured with virt-manages using NAT (with default settings). So now my virtual machine has Internet access and local IP 192.168.122.227.

On my host system I have 1 physical network interface and 1 main public ip and 3 additional public ips on it.

My public ips (example): 85.0.0.1, 85.0.0.2, 85.0.0.3, 85.0.0.4

Broadcast ips are also examples.

My ifconfig from host:

enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 85.0.0.1 netmask 255.255.255.192 broadcast 85.0.0.127
ether d4:3d:7e:ec:b3:55 txqueuelen 1000 (Ethernet)
RX packets 4920 bytes 416179 (406.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2298 bytes 392837 (383.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

enp2s0:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 85.0.0.2 netmask 255.255.255.192 broadcast 85.0.0.127
ether d4:3d:7e:ec:b3:55 txqueuelen 1000 (Ethernet)

enp2s0:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 85.0.0.3 netmask 255.255.255.192 broadcast 85.0.0.127
ether d4:3d:7e:ec:b3:55 txqueuelen 1000 (Ethernet)

enp2s0:2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 85.0.0.4 netmask 255.255.255.192 broadcast 85.0.0.127
ether d4:3d:7e:ec:b3:55 txqueuelen 1000 (Ethernet)

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
loop txqueuelen 0 (Local Loopback)
RX packets 30 bytes 2856 (2.7 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 30 bytes 2856 (2.7 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

virbr0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:cf:32:9d txqueuelen 0 (Ethernet)
RX packets 18 bytes 1407 (1.3 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 8 bytes 779 (779.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

vnet0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether fe:54:00:96:2d:23 txqueuelen 500 (Ethernet)
RX packets 18 bytes 1659 (1.6 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 574 bytes 30211 (29.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

When I do this on the host machine, I still keep coming to host machine by ssh 85.0.0.2 but not to the guest:

iptables -t nat -I PREROUTING -d 85.0.0.2 -i enp2s0:0 -j DNAT --to-destination 192.168.122.227 

iptables -t nat -I POSTROUTING -s 192.168.122.227 -o enp2s0:0 -j SNAT --to-source 85.0.0.2 iptables -P FORWARD ACCEPT

iptables -P FORWARD ACCEPT

My enp2s0:0 config:

# Generated by parse-kickstart
UUID=9928e0a6-df18-45ef-a826-edaf8b4dc370
DNS2=85.0.0.10 #(example)
DNS1=85.0.0.10 #(example)
BOOTPROTO=none
DEVICE=enp2s0:0
ONBOOT=yes
IPV6INIT="no"
TYPE=Ethernet
IPADDR=85.0.0.2
PREFIX=26
GATEWAY=85.0.0.127
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_FAILURE_FATAL=no
NAME="System enp2s0:0"

I am not stupidly duplicating question, I've already read and googled a lot, but still can't solve this problem. Please help!

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1 Answer 1

Reset to default
4

You should not have IP addresses meant for guests assigned to the host. (And you should not be using interface aliases. Those were deprecated many years ago.)

Instead, create a bridge, and add enp2s0 to it. Then assign your KVM guests to that bridge and assign their IP addresses in each guest.

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3
  • maybe you can give a link to a nice manual? I can't do it myself because almost know anything about bridges, interfaces and networking in general:(
    – tester3
    Jul 11, 2015 at 15:43
  • and if I don't create interface aliases with additional ips - they don't receive pings
    – tester3
    Jul 11, 2015 at 15:44
  • 3
    @tester3 OK, here's a link to a nice manual.
    – Michael Hampton
    Jul 11, 2015 at 15:50

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