netstat Command: Tutorial & Examples
Display network statistics
command is a versatile networking tool that is used to
display detailed network statistics. It allows you to monitor incoming and outgoing network packets, as well as
troubleshoot any issues related to the network. It's a vital tool for system and network administrators to understand
what's happening on their servers.
Understanding How the netstat Command Works
command works by querying the network stack of the Linux Kernel to provide
statistics about the network connections, routing tables, interface statistics, masquerade connections, and multicast
memberships. If you're curious about any particular network activity, netstat
is your go-to command.
Importance of the netstat Command
command is important because it helps you monitor and diagnose network-related issues. For instance, if
your server is experiencing high load, netstat
can help you identify the connection that
is causing the problem. The command is also useful for security audits as it can help identify unauthorized connections.
Typical Problems Solved by the netstat Command
can be used to troubleshoot a variety of network-related issues. For instance, it can help identify why a
connection to a certain server is failing, reveal which services are listening on which ports, and identify
potential network failures.Examples of Using the netstat Command
Here are some examples of how you can use the netstat
This basic command will display a list of active connections.
This command will show all active listening ports and non-listening ports.
This command will display the routing table.
This command will show numerical addresses instead of trying to determine symbolic host, port or user names.
Common Parameters of the netstat Command
Here are some common parameters you might use with the netstat
: Displays all connections and listening ports.-n
: Shows numerical addresses.-r
: Displays the kernel routing tables.-t
: Displays TCP connections.-u
: Displays UDP connections.Typical Output of the netstat Command
Here's an example of typical output from the netstat
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
udp 0 0 0.0.0.0:68 0.0.0.0:*
Each line represents a network connection, and the columns provide information about that connection, such as the protocol being used, the local and foreign address, and the state of the connection.
Common Issues When Using the netstat Command
is a powerful tool, there are a few common issues you might encounter. For example, if you see a lot of
connections in the TIME_WAIT state, it could mean that your system is being targeted by
a SYN flood attack. Also, be aware that netstat
might take a long time to resolve
hostnames if you have a slow DNS server. This can be avoided by using the -n
option to display numerical addresses