I am looking for the answer for few days and any configuration is right for me to set the networking working.
I have CentOS 7 (10.120.0.57) with installed KVM on it. I created simple guest (10.120.0.58) vm with CentOS7 as well, but I have some problem with network on the guest. Host can access to the internet, and it can ping the guest machine. Guest can ping host as well, but when it ping some other IP it get: Destination Unreachable. I disabled in advance firewalld and selinux on both machines to eliminate problems.
My hosts bridge should pass traffic because I set /etc/sysctl.conf (!!!)
net.ipv4.ip_forward = 1
net.ipv4.conf.all.proxy_arp = 1
On Host in tcpdump I can see the ICMP packets from guest but it's only in one way requests (no replies), when I try to ping the real gateway of the network (10.120.0.1)
IP 10.120.0.58 > gateway: ICMP echo request, id 3716, seq 1, length 64
IP 10.120.0.58 > gateway: ICMP echo request, id 3716, seq 2, length 64
If I ping from guest e.g google.com (tcpdump from host):
IP localhost.localdomain > 10.120.0.58: ICMP localhost.localdomain udp port domain unreachable, length 64
IP localhost.localdomain > 10.120.0.58: ICMP localhost.localdomain udp port domain unreachable, length 64
But of course ping is working when I ping Guest (10.120.0.58)<=> Host(10.120.0.57):
10.120.0.58 > localhost.localdomain: ICMP echo request, id 3719, seq 8, length 64
localhost.localdomain > 10.120.0.58: ICMP echo reply, id 3719, seq 8, length 64
Could someone enlight me what is wrong with my Host/Guest configuration?
HOST:
ifconfig -a:
br0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.120.0.57 netmask 255.255.255.0 broadcast 10.120.0.255
inet6 fe80::20c:29ff:fed5:14fa prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:d5:14:fa txqueuelen 1000 (Ethernet)
RX packets 74849 bytes 6444652 (6.1 MiB)
RX errors 0 dropped 100 overruns 0 frame 0
TX packets 1033 bytes 88046 (85.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eno16780032: flags=4419<UP,BROADCAST,RUNNING,PROMISC,MULTICAST> mtu 1500
inet6 fe80::20c:29ff:fed5:14fa prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:d5:14:fa txqueuelen 1000 (Ethernet)
RX packets 2975 bytes 239252 (233.6 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 164 bytes 23286 (22.7 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
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 1 (Local Loopback)
RX packets 6 bytes 644 (644.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 6 bytes 644 (644.0 B)
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 52:54:00:9f:de:66 txqueuelen 1000 (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-nic: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 52:54:00:9f:de:66 txqueuelen 1000 (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
vnet0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether fe:54:00:7f:c5:c5 txqueuelen 1000 (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 5885 overruns 0 carrier 0 collisions 0
vnet1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether fe:54:00:b0:3d:40 txqueuelen 1000 (Ethernet)
RX packets 420 bytes 34697 (33.8 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 111762 bytes 9374955 (8.9 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
br0 configuration:
DEVICE=br0
BOOTPROTO=static
TYPE=Bridge
ONBOOT=yes
IPADDR="10.120.0.57"
NETMASK="255.255.255.0"
#GATEWAY="10.120.0.1"
#DNS1="10.120.0.1"
#DNS2="8.8.8.8"
STP=yes
DELAY=0
NM_CONTROLLED=no
eno16780032 configuration:
TYPE="Ethernet"
#NAME="eno16780032"
#UUID="4fc9740c-536a-4330-aab4-bdef7489582f"
DEVICE="eno16780032"
ONBOOT="yes"
NM_CONTROLLED=no
BRIDGE=br0
bridge:
bridge name bridge id STP enabled interfaces
br0 8000.000c29d514fa yes eno16780032
vnet0
vnet1
virbr0 8000.5254009fde66 yes virbr0-nic
Hosts /etc/sysconfig/network:
# Created by anaconda
NETWORKING=yes
GATEWAY=10.120.0.1
Guest eth0 configuration:
DEVICE=eth0
NAME=eth0
TYPE=Ethernet
BOOTPROTO=static
ONBOOT=yes
IPADDR="10.120.0.58"
NETMASK="255.255.255.0"
GATEWAY="10.120.0.57" (!?)
DNS1="10.120.0.57"
DNS2="8.8.8.8"
Thank you in advance for taking a look.
EDIT
I add the iptables result from the host:
[root@localhost ~]# iptables -L -v -n -t nat
Chain PREROUTING (policy ACCEPT 59 packets, 4981 bytes)
pkts bytes target prot opt in out source destination
Chain INPUT (policy ACCEPT 34 packets, 3619 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 2 packets, 103 bytes)
pkts bytes target prot opt in out source destination
Chain POSTROUTING (policy ACCEPT 2 packets, 103 bytes)
pkts bytes target prot opt in out source destination
Iptables from the guest:
[root@localhost ~]# iptables -L -v -n -t nat
Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Tracepath from the guest(10.120.0.58) to 8.8.8.8:
1?: [LOCALHOST] pmtu 1500
1: 10.120.0.58 3012.516ms !H
Resume: pmtu 1500
EDIT2
I add iptables -L -v -n results.
From Host:
[root@localhost ~]# iptables -L -v -n
Chain INPUT (policy ACCEPT 162K packets, 17M bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 8 packets, 476 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 3894 packets, 309K bytes)
pkts bytes target prot opt in out source destination
From guest:
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Best Answer
Since you bridged the physical device of your host with the virtual machine ( I guess
vnet0and/orvnet1are the devices that are used for the VM ), you have physical access to the10.120.0.0/24network within your VM.So you should replace
by