OUTPUT
Active Internet connections (TCP, UDP, raw)
Proto
The protocol (tcp, udp, raw) used by the socket.
Recv-Q
The count of bytes not copied by the user program connected to this socket.
Send-Q
The count of bytes not acknowledged by the remote host.
Local Address
Address and port number of the local end of the socket. Unless the --numeric (-n) option is specified, the
socket address is resolved to its canonical host name (FQDN), and the port number is translated into the
corresponding service name.
Foreign Address
Address and port number of the remote end of the socket. Analogous to "Local Address."
State
The state of the socket. Since there are no states in raw mode and usually no states used in UDP, this column may be left blank. Normally this can be one of several values:
ESTABLISHED
The socket has an established connection.
SYN_SENT
The socket is actively attempting to establish a connection.
SYN_RECV
A connection request has been received from the network.
FIN_WAIT1
The socket is closed, and the connection is shutting down.
FIN_WAIT2
Connection is closed, and the socket is waiting for a shutdown from the remote end.
TIME_WAIT
The socket is waiting after close to handle packets still in the network.
CLOSED The socket is not being used.
CLOSE_WAIT
The remote end has shut down, waiting for the socket to close.
LAST_ACK
The remote end has shut down, and the socket is closed. Waiting for acknowledgement.
LISTEN The socket is listening for incoming connections. Such sockets are not included in the output unless
you specify the --listening (-l) or --all (-a) option.
CLOSING
Both sockets are shut down but we still don’t have all our data sent.
UNKNOWN
The state of the socket is unknown.
User
The username or the user id (UID) of the owner of the socket.
PID/Program name
Slash-separated pair of the process id (PID) and process name of the process that owns the socket. --pro-
gram causes this column to be included. You will also need superuser privileges to see this information on
sockets you don’t own. This identification information is not yet available for IPX sockets.
Timer
(this needs to be written)
Active UNIX domain Sockets
Proto
The protocol (usually unix) used by the socket.
RefCnt
The reference count (i.e. attached processes via this socket).
Flags
The flags displayed is SO_ACCEPTON (displayed as ACC), SO_WAITDATA (W) or SO_NOSPACE (N). SO_ACCECPTON is
used on unconnected sockets if their corresponding processes are waiting for a connect request. The other
flags are not of normal interest.
Type
There are several types of socket access:
SOCK_DGRAM
The socket is used in Datagram (connectionless) mode.
SOCK_STREAM
This is a stream (connection) socket.
SOCK_RAW
The socket is used as a raw socket.
SOCK_RDM
This one serves reliably-delivered messages.
SOCK_SEQPACKET
This is a sequential packet socket.
SOCK_PACKET
Raw interface access socket.
UNKNOWN
Who ever knows what the future will bring us - just fill in here :-)
State
This field will contain one of the following Keywords:
FREE The socket is not allocated
LISTENING
The socket is listening for a connection request. Such sockets are only included in the output if
you specify the --listening (-l) or --all (-a) option.
CONNECTING
The socket is about to establish a connection.
CONNECTED
The socket is connected.
DISCONNECTING
The socket is disconnecting.
(empty)
The socket is not connected to another one.
UNKNOWN
This state should never happen.
PID/Program name
Process ID (PID) and process name of the process that has the socket open. More info available in Active
Internet connections section written above.
Path
This is the path name as which the corresponding processes attached to the socket.
Active IPX sockets
(this needs to be done by somebody who knows it)
Active NET/ROM sockets
(this needs to be done by somebody who knows it)
Active AX.25 sockets
(this needs to be done by somebody who knows it)
NOTES
Starting with Linux release 2.2 netstat -i does not show interface statistics for alias interfaces. To get
per alias interface counters you need to setup explicit rules using the ipchains(8) command.
FILES
/etc/services -- The services translation file
/proc -- Mount point for the proc filesystem, which gives access to kernel status information via the fol-
lowing files.
/proc/net/dev -- device information
/proc/net/raw -- raw socket information
/proc/net/tcp -- TCP socket information
/proc/net/udp -- UDP socket information
/proc/net/igmp -- IGMP multicast information
/proc/net/unix -- Unix domain socket information
/proc/net/ipx -- IPX socket information
/proc/net/ax25 -- AX25 socket information
/proc/net/appletalk -- DDP (appletalk) socket information
/proc/net/nr -- NET/ROM socket information
/proc/net/route -- IP routing information
/proc/net/ax25_route -- AX25 routing information
/proc/net/ipx_route -- IPX routing information
/proc/net/nr_nodes -- NET/ROM nodelist
/proc/net/nr_neigh -- NET/ROM neighbours
/proc/net/ip_masquerade -- masqueraded connections
/proc/net/snmp -- statistics
SEE ALSO
route(8), ifconfig(8), ipchains(8), iptables(8), proc(5)
BUGS
Occasionally strange information may appear if a socket changes as it is viewed. This is unlikely to occur.
If the sctp module is not added to the kernel, running netstat with the -A inet or -A inet6 option abnor-
mally terminates with the following message:
netstat: no support for ‘AF INET (sctp)’ on this system.
To avoid this, install the sctp kernel module.
轉載自 http://www.cnblogs.com/ggjucheng/archive/2012/01/08/2316661.html
總結常用選項
#netstat -tupln
t:tcp
u:udp
p:PID
l:listening
n:顯示數字而不是主機、端口、用戶名