Why VM2 can't ping one machine?

Hello,
I created three Fedora Server VMs in the VirtualBox as below:

VM1 (node1) : Two NICs (Internal Network, NAT)
VM2 (node2) : Two NICs (Internal Network, NAT)
VM3 (node3) : One NIC  (Internal Network)

VM1 can see VM2 and VM3, but VM2 just see VM1. In other words, VM2 and VM3 can’t see each other!

On VM1:

# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         _gateway        0.0.0.0         UG    101    0        0 enp0s8
10.0.3.0        0.0.0.0         255.255.255.0   U     101    0        0 enp0s8
192.168.1.0     0.0.0.0         255.255.255.0   U     100    0        0 enp0s3

And:

# ping node2
PING node2 (192.168.1.10) 56(84) bytes of data.
64 bytes from node2 (192.168.1.10): icmp_seq=1 ttl=64 time=0.462 ms
64 bytes from node2 (192.168.1.10): icmp_seq=2 ttl=64 time=0.619 ms
64 bytes from node2 (192.168.1.10): icmp_seq=3 ttl=64 time=0.659 ms
^C
--- node2 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 0.462/0.580/0.659/0.085 ms

And:

# ping node3
PING 192.168.1.4 (192.168.1.4) 56(84) bytes of data.
64 bytes from 192.168.1.4: icmp_seq=1 ttl=64 time=0.469 ms
64 bytes from 192.168.1.4: icmp_seq=2 ttl=64 time=0.654 ms
64 bytes from 192.168.1.4: icmp_seq=3 ttl=64 time=0.624 ms
^C
--- 192.168.1.4 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2032ms
rtt min/avg/max/mdev = 0.469/0.582/0.654/0.081 ms

On VM2:

# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.0.3.2        0.0.0.0         UG    101    0        0 enp0s8
10.0.3.0        0.0.0.0         255.255.255.0   U     101    0        0 enp0s8
192.168.1.0     0.0.0.0         255.255.255.0   U     100    0        0 enp0s3

And:

# ping node1
PING node1 (192.168.1.3) 56(84) bytes of data.
64 bytes from node1 (192.168.1.3): icmp_seq=1 ttl=64 time=0.233 ms
64 bytes from node1 (192.168.1.3): icmp_seq=2 ttl=64 time=0.473 ms
64 bytes from node1 (192.168.1.3): icmp_seq=3 ttl=64 time=0.586 ms
^C
--- node1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2034ms
rtt min/avg/max/mdev = 0.233/0.430/0.586/0.147 ms

And:

# ping node3
PING 192.168.1.4 (192.168.1.4) 56(84) bytes of data.

Why? Is the route table wrong on VM2?

Thank you.

1 Like

More information:

On VM1:

[root@node1 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:f5:e1:55 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.3/24 brd 192.168.1.255 scope global noprefixroute enp0s3
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fef5:e155/64 scope link 
       valid_lft forever preferred_lft forever
3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:35:92:d2 brd ff:ff:ff:ff:ff:ff
    inet 10.0.3.15/24 brd 10.0.3.255 scope global dynamic noprefixroute enp0s8
       valid_lft 86165sec preferred_lft 86165sec
    inet6 fe80::948f:e722:5c57:7746/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

On VM2:

[root@node2 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:05:d9:69 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.10/24 brd 192.168.1.255 scope global noprefixroute enp0s3
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fe05:d969/64 scope link 
       valid_lft forever preferred_lft forever
3: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:80:56:8d brd ff:ff:ff:ff:ff:ff
    inet 10.0.3.15/24 brd 10.0.3.255 scope global dynamic noprefixroute enp0s8
       valid_lft 86243sec preferred_lft 86243sec
    inet6 fe80::128e:b5d1:fdc5:e0bc/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

On VM3:

[root@node3 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:c3:b2:6f brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.4/32 scope global noprefixroute enp0s3
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fec3:b26f/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

What is the problem?

Is this topic not obsolete since we discussed it here? :

1 Like