netstat.8

来自「Linux下网络相关工具源代码。」· 8 代码 · 共 500 行

.\"
.\" netstat.8 
.\"
.\" Original: ([e-mail] & [e-mail])
.\"
.\" Modified: [e-mail]
.\" Modified: Andi Kleen [e-mail] 
.\" Modified: Tuan Hoang [e-mail] 
.\"
.\"
.TH NETSTAT 8 "20 April 1999" "net-tools" "Linux Programmer's Manual"

.SH NAME
netstat \- Display network connections, routing tables, interface statistics, masquerade connections, netlink messages, and multicast memberships

.SH SYNOPSIS

.B netstat 
.RB [ \-venaoc ]
.RB [ \-\-tcp | \-t ]
.RB [ \-\-udp | \-u ]
.RB [ \-\-raw | \-w ]
.RB [ \-\-groups | \-g ]
.RB [ \-\-unix | \-x ] 
.RB [ \-\-inet | \-\-ip ]
.RB [ \-\-ax25 ]
.RB [ \-\-ipx ] 
.RB [ \-\-netrom ]

.PP

.B netstat 
.RB [ \-veenc ]
.RB [ \-\-inet ] 
.RB [ \-\-ipx ]
.RB [ \-\-netrom ] 
.RB [ \-\-ddp ]
.RB [ \-\-ax25 ]
.RB { \-\-route | \-r }

.PP

.B netstat
.RB [ \-veenpac ]
.RB { \-\-interfaces | \-i }
.RI [ iface ]

.PP

.B netstat
.RB [ \-enc ]
.RB { \-\-masquerade | \-M }

.PP

.B netstat 
.RB [ \-cn ]
.RB { \-\-netlink | \-N }

.PP

.B netstat 
.RB { \-V | \-\-version }
.RB { \-h | \-\-help }

.PP
.SH DESCRIPTION
.B Netstat
displays information of the Linux networking subsystem.

.SS "(no option)"
You can view the
status of network connections by listing the open sockets. This is the
default operation: If you don't specify any address families, then the
active sockets of all configured address families will be printed. With
.B -e
you get some additional informations (userid). With the
.B -v
switch you can make netstat complain about known address families which are
not supported by the kernel. The
.B -o
option displays some additional information on networking timers. Enabling the
.B -p
will show you the process PID and name of the program holding the socket.
.B -a
print all sockets, including the listening server sockets. The address
family
.B inet
will display raw, udp and tcp sockets.

.SS "\-r, \-\-route"
With the
.BR \-r ", " \-\-route
option, you get the kernel routing tables in the same format as
.B "route -e" 
use.
.B "netstat -er" 
will use the output format of
.BR route .
Please see
.BR route (8)
for details.

.SS "\-g, \-\-groups"
With the
.BR \-g ", " \-\-groups 
option, IGMP multicast group membership information for IPv4 and IPv6 is displayed.

.SS "\-i, \-\-interface \fIiface\fI"
If you use the
.BR -i ", " --interfaces
option, a table of all (or the specified 
.IR iface ) 
networking interfaces will be printed. The output uses the
.B "ifconfig -e"
format, and is described in
.BR ifconfig (8).
.B "netstat -ei" 
will print a table or a single interface entry just like
.B ifconfig
does. With the
.B -a
switch, you can include interfaces which are not configured (i.e. don't have
the 
.BR U = UP
flag set).

.SS "\-M, \-\-masquerade"

A list of all masqueraded sessions can be viewed, too. With the
.B -e 
switch you can include some more informations about sequenze numbering and
deltas, caused by data rewrites on FTP sessions (PORT
command). Masquerade support is used to hide hosts with unofficial network
addresses from the outside world, as described in
.BR ipfw (4), ipfwadm "(8) and " ipfw (8).

.SS "\-N, \-\-netlink"

Recent kernels have a kernel/user communication support called netlink. You
can get messages about creation or deletion of interfaces or routes from
.I /dev/route
(36,0).

.PP
.SH OPTIONS
.SS "\-v, \-\-verbose"
Tell the user what is going on by being verbose. Especially print some
usefull informations about unconfigured address families.

.SS "\-n, \-\-numeric"
shows numerical addresses instead of trying to determine symbolic host, port
or user names.

.SS "\-p, \-\-programs"
displays process name and PID of the owner of each socket it dumps. You
have to be the owner of such process to have all it's sockets matched to it
or generally
.B root
user will see all the necessary information in place.

.SS "\-A, \-\-af \fIfamily\fI"
use a different method to set the address families.
.I family 
is a comma (',') seperated list of address family keywords like
.BR inet , 
.BR unix , 
.BR ipx , 
.BR ax25 , 
.B netrom 
and
.BR ddp .
This is has the same effect as using the long options
.BR \-\-inet ,
.BR \-\-unix ,
.BR \-\-ipx ,
.BR \-\-ax25 ,
.B \-\-netrom
and
.BR \-\-ddp.

.SS "\-c, \-\-continous"
This will cause
.B netstat
to print the selected table every second continously on the screen until you
interrupt it.

.PP
.SH OUTPUT

.PP
.SS Active Internet connections \fR(TCP, UDP, RAW)\fR

.SS "Proto" 
The protocol (tcp, udp, raw) used by the socket. 

.SS "Recv-Q"
The count of bytes not copied by the user program connected to this socket.

.SS "Send-Q"
The count of bytes not acknoledged by the remote host.

.SS "Local Address" 
The local address (local hostname) and port number of the socket. Unless
the
.B -n
switch is given, the socket address is resolved to its canonical
hostname, and the port number is translated into the corresponding service
name. 

.SS "Foreign Address"
The remote address (remote hostname) and port number of he socket. As
with the local address:port, the
.B -n
switch turns off hostname and service name resolution.

.SS "State"
The state of the socket. Since there are no states in RAW and usually no
states used in UDP, this row may be left blank. Normally this can be one
of several values:
.TP
.I
ESTABLISHED
The socket has an established connection.
.TP
.I
SYN_SENT
The socket is actively attempting to establish a connection.
.TP
.I
SYN_RECV
A connection request has been received from the network.
.TP
.I
FIN_WAIT1
The socket is closed, and the connection is shutting down.
.TP
.I
FIN_WAIT2
Connection is closed, and the socket is waiting for a shutdown from the
remote end.
.TP
.I
TIME_WAIT
The socket is waiting after close to handle packets still in the network.
.TP
.I
CLOSED
The socket is not being used.
.TP
.I
CLOSE_WAIT
The remote end has shut down, waiting for the socket to close.
.TP
.I
LAST_ACK
The remote end shut down, and the socket is closed. Waiting for
acknowledgement.
.TP
.I
LISTEN
The socket is listening for incoming connections. Those sockets are only
displayed if the
.BR -a , --listening
switch is set.
.TP
.I
CLOSING
Both sockets are shut down but we still don't have all our data
sent.
.TP
.I
UNKNOWN
The state of the socket is unknown.

.SS "User"
The name or the UID of the owner of the socket.

.SS "PID/Program name"
Slash-separated pair of the PID and process name of the program holding
this socket. Option
.B -p
enables display of this column. You will also need
.B root
privileges as you have to have access rights to process to be able to see
the program's sockets matched up to it. This identification information
is not yet available for IPX sockets.

.SS "Timer"
(this needs to be written)


.PP
.SS Active UNIX domain Sockets


.SS "Proto" 
The protocol (usually unix) used by the socket.

.SS "RefCnt"
The reference count (i.e. attached processes via this socket).

.SS "Flags"
The flags displayed is SO_ACCEPTON (displayed as 
.BR ACC ),
SO_WAITDATA 
.RB ( W )
or SO_NOSPACE 
.RB ( 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.

.SS "Type"
There are several types of socket access:
.TP
.I
SOCK_DGRAM
The socket is used in Datagram (connectionless) mode.
.TP
.I
SOCK_STREAM
This is a stream (connection) socket.
.TP
.I
SOCK_RAW
The socket is used as a raw socket.
.TP
.I
SOCK_RDM
This one serves reliably-delivered messages.
.TP
.I
SOCK_SEQPACKET
This is a sequential packet socket.
.TP
.I
SOCK_PACKET
RAW interface access socket.
.TP
.I
UNKNOWN
Who ever knows, what the future will bring us - just fill in here :-)

.PP
.SS "State"
This field will contain one of the following Keywords:
.TP
.I
FREE
The socket is not allocated
.TP
.I
LISTENING
The socket is listening for a connection request. Those sockets are only
displayed if the
.BR -a , --listening
switch is set.
.TP
.I
CONNECTING
The socket is about to establish a connection.
.TP
.I
CONNECTED
The socket is connected.
.TP
.I
DISCONNECTING
The socket is disconnecting.
.TP
.I
(empty)
The socket is not connected to another one.
.TP
.I
UNKNOWN
This state should never happen.

.SS "PID/Program name"
PID and process name of the program holding this socket. More info available in
.B "Active Internet connections"
section written above.

.SS "Path"
This displays the path name as which the corresponding processes attached
to the socket.

.PP
.SS Active IPX sockets

(this needs to be done by somebody who knows it)

.PP
.SS Active NET/ROM sockets

(this needs to be done by somebody who knows it)

.PP
.SS Active AX.25 sockets

(this needs to be done by somebody who knows it)

.PP
.SH NOTES
Since kernel release 2.2 netstat -i does not display interface statistics for
alias interfaces anymore. To get per alias interface counters you need to
setup explicit rules using the 
.BR ipchains(8) 
command.  

.SH FILES
.ta
.I /etc/services
-- The services translation file

.I /proc/net/dev
-- devices information

.I /proc/net/raw
-- RAW socket information


.I /proc/net/tcp
-- TCP socket information

.I /proc/net/udp
-- UDP socket information

.I /proc/net/igmp
-- IGMP multicast information

.I /proc/net/unix
-- Unix domain socket information

.I /proc/net/ipx
-- IPX socket information

.I /proc/net/ax25
-- AX25 socket information

.I /proc/net/appletalk
-- DDP (appletalk) socket information

.I /proc/net/nr
-- NET/ROM socket information

.I /proc/net/route
-- Kernel IP routing information

.I /proc/net/ax25_route
-- Kernel AX25 routing information

.I /proc/net/ipx_route
-- Kernel IPX routing information

.I /proc/net/nr_nodes
-- Kernel NET/ROM nodelist

.I /proc/net/nr_neigh
-- Kernel NET/ROM neighbours

.I /proc/net/ip_masquerade
-- Kernel masqueraded connections

.fi

.PP
.SH SEE ALSO
.BR route (8), 
.BR ifconfig (8), 
.BR ipfw (4), 
.BR ipfw (8), 
.BR ipfwadm (8)
.BR ipchains (8)

.PP
.SH BUGS
Occasionally strange information may appear if a socket changes
as it is viewed. This is unlikely to occur.
.br
The
.B netstat -i
options is described as it should work after some code cleanup of the BETA
release of the net-tools package.

.PP
.SH AUTHORS
The netstat user interface was written by Fred Baumgarten
<[e-mail]> the man page basically
by Matt Welsh <[e-mail]>. It was updated by
Alan Cox <[e-mail]> but could do with a bit more
work.  It was updated again by Tuan Hoang
<[e-mail]>.
.br
The man page and the command included in the net-tools
package is totally rewritten from Bernd Eckenfels 
<[e-mail]>.