netstat is a command line network utility that shows network connections for the Transmission Control Protocol (both incoming and outgoing), routing tables and a series of network interfaces (network interface controller or interface software defined network) and network protocol statistics. It is available on Unix-like operating systems, including macOS, Linux, Solaris and BSD, and is available on IBM OS / 2 and on Microsoft Windows NT-based operating systems, including Windows XP, Windows Vista, Windows 7, Windows 8 and Windows 10.
Netstat, derived from the words network and statistics and is a command line utility used by system administrators to analyze network statistics. Show a whole set of statistics such as open ports and corresponding addresses on the host system, routing table and more.
The package that contains netstat is called net-tools. In modern systems the netstat utility is preinstalled and it is not necessary to install it in the case of not installing the minimum version of the Linux system, in the case of installing the minimum version of the system we may not be able to execute the netstat command because it is not installed in our system.
On older systems you are likely to encounter some error when executing the netstat command. One way to correct this error is to reinstall the net-tools.
To install the net-tools and to be able to execute the netstat command on our system we execute the following command to install the tool.
CentOS/RHEL
# yum install net-tools
Debian/Ubuntu
# apt install net-tools
OpenSuse
# zypper install net-tools
Arch Linux
# pacman -S netstat-nat
We can check the version of netstat installed in our system with the following command.
# netstat -v
We can display the help information of the tool with the command (help)
# netstat help
[root@serv23 ~]# netstat help
usage: netstat [-vWeenNcCF] [<Af>] -r netstat {-V|--version|-h|--help}
netstat [-vWnNcaeol] [<Socket> ...]
netstat { [-vWeenNac] -I[<Iface>] | [-veenNac] -i | [-cnNe] -M | -s [-6tuw] } [delay]
-r, --route display routing table
-I, --interfaces=<Iface> display interface table for <Iface>
-i, --interfaces display interface table
-g, --groups display multicast group memberships
-s, --statistics display networking statistics (like SNMP)
-M, --masquerade display masqueraded connection
-v, --verbose be verbose
-W, --wide don't truncate IP addresses
-n, --numeric don't resolve names
--numeric-hosts don't resolve host names
--numeric-ports don't resolve port names
--numeric-users don't resolve user names
-N, --symbolic resolve hardware names
-e, --extend display other/more information
-p, --programs display PID/Program name for sockets
-o, --timers display timers
-c, --continuous continuous listing
-l, --listening display listening server sockets
-a, --all display all sockets (default: connected)
-F, --fib display Forwarding Information Base (default)
-C, --cache display routing cache instead of FIB
-Z, --context display SELinux security context for sockets
<Socket>={-t|--tcp} {-u|--udp} {-U|--udplite} {-S|--sctp} {-w|--raw}
{-x|--unix} --ax25 --ipx --netrom
<AF>=Use '-6|-4' or '-A <af>' or '--<af>'; default: inet
List of possible address families (which support routing):
inet (DARPA Internet) inet6 (IPv6) ax25 (AMPR AX.25)
netrom (AMPR NET/ROM) ipx (Novell IPX) ddp (Appletalk DDP)
x25 (CCITT X.25)
Some examples of the execution of the netstat command
1.Tabla de enrutamiento de red
Using the [-r] parameter it will show us information related to the routing of our network and [-n] displays information related to the active connections tcp protocol.
[root@serv ~]# netstat -nr
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
Using the parameter [-i] we can obtain information about the configuration of our network and with the option [-a] it prints all the interfaces present.
2. Interfaz de red
[root@serv23 ~]# netstat -ai
Kernel Interface table
Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 161831 0 6 0 43092 0 0 0 BMRU
lo 65536 240 0 0 0 240 0 0 0 LRU