1. Bug description
This is a problem I encountered when installing a virtual machine before. I have been drafted for a long time. Today I finally have time to improve and publish it.
When you enter ifconfig, you must be able to find the local loopback.
2. Possible reasons for errors
Reason 1: Hardware issues
A common cause of Ubuntu without network connections is hardware failures, such as network cable damage, network card failure, or router problems.
Reason 2: Driver problem
Another possible reason is that the drivers of the network adapter are incompatible or not installed correctly.
Reason 3: System setup problems
Improper Ubuntu system settings, such as network configuration files incorrectly or network services not started, may also lead to no network connection.
Reason 4: Network service issues
Network services such as NetworkManager are not running or are configured incorrectly, which can also cause network connection problems.
Example: Find possible causes
Example Code 1: Checking for Physical Connections
To check whether the physical connection is normal, you can test the network connection through simple command line operations:
ping -c 4
This command will try to send 4 ICMP echo requests. If a response is received, it means that the physical connection is normal.
Example Code 2: Check the driver
Check that the network adapter driver is installed correctly:
lspci -vnn | grep -iA2 net
This command lists all network interfaces and their details, including driver status.
Example Code 3: Check the network configuration file
Check the /etc/network/interfaces file to ensure the network configuration is correct:
cat /etc/network/interfaces
This command will display the contents of the network configuration file. You can check whether there is a correct configuration, such as:
auto eth0 iface eth0 inet dhcp
This means that the eth0 interface is automatically configured and the IP address is obtained using DHCP.
Example Code 4: Diagnostic Network Services
Use the nmcli command line tool to diagnose network services:
nmcli d
This command will display the status of all network devices, including whether to connect or not.
3. Solution summary
Solution 1: Restart the network
Start the network service and enter the password
sudo systemctl start NetworkManager
Restart the network service
sudo systemctl restart NetworkManager
Solution 2: Solve Ubuntu's NetworkManager problem
To update the NetworkManager configuration, you must first have gedit or vim, and either one of them is random. If you use gedit here, just use gedit first. If there is no, get gedit first. If there is one, go straight to the next step.
apt-get install gedit
Open with gedit
gedit /etc/NetworkManager/
Change the fifth line managed=False to managed=True , and then save ctrl+s and exit.
Delete NetworkManager configuration
service NetworkManager stop rm /var/lib/NetworkManager/ service NetworkManager start
Then restart to restore the network identity.
Solution 3: VM virtual machine management settings
Change the network adapter in vm from NAT mode to bridge mode, or switch from bridge mode to NAT mode.
4. Summary
This is the end of this article about the solution to Ubuntu’s networkless connection and identification. For more information about Ubuntu’s networkless connection and identification, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!