netstat shows network connections, routing tables
(-r
), interfaces (-i
), masquerade
connections (-M
), multicast memberships
(-g
), and statistics (-s
).
tester@linux:~> netstat -r Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 192.168.22.0 * 255.255.254.0 U 0 0 0 eth0 link-local * 255.255.0.0 U 0 0 0 eth0 loopback * 255.0.0.0 U 0 0 0 lo default 192.168.22.254 0.0.0.0 UG 0 0 0 eth0
tester@linux:~> netstat -i Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg eth0 1500 0 1624507 129056 0 0 7055 0 0 0 BMNRU lo 16436 0 23728 0 0 0 23728 0 0 0 LRU
When displaying network connections or statistics, you can specify the
socket type to display: TCP (-t
), UDP
(-u
), or raw (-r
). The
-p
option shows the PID and name of the program to which each
socket belongs.
The following example lists all TCP connections and the programs using these connections.
linux:~ # netstat -t -p Active Internet connections (w/o servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Pro tcp 0 0 linux:33513 www.novell.com:www-http ESTABLISHED 6862/fi tcp 0 352 linux:ssh linux2.:trc-netpoll ESTABLISHED 19422/s tcp 0 0 localhost:ssh localhost:17828 ESTABLISHED -
In the following, statistics for the TCP protocol are displayed:
tester@linux:~> netstat -s -t Tcp: 2427 active connections openings 2374 passive connection openings 0 failed connection attempts 0 connection resets received 1 connections established 27476 segments received 26786 segments send out 54 segments retransmited 0 bad segments received. 6 resets sent [...] TCPAbortOnLinger: 0 TCPAbortFailed: 0 TCPMemoryPressures: 0