Frequently asked questions for Networking
In this section we collect all frequently asked questions about Networking. Do you have a question or one that really should be listed here? Share your feedback. Thanks for your contribution!
How to see active connections and bandwidth usage on Linux
Show the bandwidth usage and active connections by using the iftop tool on Linux. Learn how to use the tool to quickly find out this information.
How to see all DNS requests on the system?
Looking for all DNS requests made on a Linux system? Tools like dnstop, firejail, and tcpdump can help to find what is being queried.
How to see errors and dropped packets on a network interface on Linux
Show the network link details using the ip command to find out if a network has errors or dropped packets on a Linux system.
How to see open ports on Linux
Show which UDP/TCP ports are opened on a Linux system, including the related process. Use the ss tool to see more details about these sockets.
How to see the default gateway on Linux
Use the network routing table to discover the default gateway on a Linux system. Here is how to use the ip command to achieve this
How to see the IP address of your internet connection
Show the IP address of your internet connection using the dig or the curl command. Learn which options can be used to find out this information.
How to see the number of open connections on Linux
Linux has in-depth details, including about network connections. Show the number of open connections using the ss command on Linux.
How to see the the network IP address of your system
Show IP address information on Linux with the help of the ip command. Learn which subcommands to use to query the relevant details.
How to see the TTL value of a DNS record
Learn how to query the Time To Live (TTL) for a DNS record by using the dig tool on a Linux systems, including any relevant options.
How to see which DNS server is used
Find the active DNS server being used by reviewing the network configuration, including common commands to query this information.
How to see which process is using a port
TCP or UDP ports can already be in use when starting up a service. Find out which process opened an UDP or TCP port on Linux by using the ss command.
How to show network TCP statistics and counters
Show counters related to the TCP connections by using the nstat command. This small utility will quickly retrieve the related statistics and display them.
Show to clear the DNS cache with systemd
Linux with systemd might doing DNS resolving using its resolver daemon. Learn how to inspect and clear the DNS cache when using the systemd resolver daemon.