Emmanuel Corrales

Emmanuel Corrales

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How to enable internet access of CentOS 7 on VirtualBox

13 Jun 2019

I was setting up a CentOS 7 virtual machine using VirtualBox to replicate an existing setup when I discovered that I cannot access the internet even though my VM was setup to use a bridged adapter.

Diagnosing the problem

I wanted to know the status of network interfaces on my virtual machine so I execute the nmcli command.

$ nmcli
enp0s3: disconnected
        "Intel 82540EM"
        1 connection available
        ethernet (e1000), 08:00:27:A7:B4:52, autoconnect, hw, mtu 1500

lo: unmanaged
        "lo"
        loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536

Use "nmcli device show" to get complete information about known devices and
"nmcli connection show" to get an overview on active connection profiles.

Consult nmcli(1) and nmcli-examples(5) manual pages for complete usage details.

The command shows that enp0s3 is diconnected so I checked its network configuration script.

$ cat /etc/sysconfig/network-scripts/ifcfg-enp0s3
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=dhcp
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=enp0s3
UUID=1056c9af-dc47-429b-958c-d0e83b99d60f
DEVICE=enp0s3
ONBOOT=no

I found out that the reason I have no access to the internet is because it is not configured to be activated on boot. The last line ONBOOT=no means that this network interface won’t be activated on startup.

Configuring the network interface

To resolve this I opened a text editor to edit the network configuration and changed the last line to ONBOOT=yes.

sudo vi /etc/sysconfig/network-scripts/ifcfg-enp0s3

I have to restart the network and apply the changes.

sudo systemctl restart network.service

Now if I check the interface, it would show that it is connected.

$ nmcli
enp0s3: connected to enp0s3
        "Intel 82540EM"
        ethernet (e1000), 08:00:27:A7:B4:52, hw, mtu 1500
        ip4 default
        inet4 10.0.2.15/24
        route4 0.0.0.0/0
        route4 10.0.2.0/24
        inet6 fe80::f63f:8611:805b:579d/64
        route6 fe80::/64
        route6 ff00::/8

lo: unmanaged
        "lo"
        loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536

DNS configuration:
        servers: 17.83.200.200 17.83.200.202
        domains: apple.com
        interface: enp0s3

Use "nmcli device show" to get complete information about known devices and
"nmcli connection show" to get an overview on active connection profiles.

Consult nmcli(1) and nmcli-examples(5) manual pages for complete usage details.

Testing access to the internet

Now to check if my virtual machine has access to the internet.

$ ping google.com
PING google.com (74.125.24.138) 56(84) bytes of data.
64 bytes from 74.125.24.138 (74.125.24.138): icmp_seq=1 ttl=41 time=71.7 ms
64 bytes from 74.125.24.138 (74.125.24.138): icmp_seq=2 ttl=41 time=73.8 ms
64 bytes from 74.125.24.138 (74.125.24.138): icmp_seq=3 ttl=41 time=73.1 ms

The command above shows that my virtual machine can now successfully connect to the internet.

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