netstat.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)netstat.1	8.2	11/7/90
.TH netstat 1
.SH Name
netstat \- show network status
.SH Syntax
.B netstat
[ 
.B \-Aan
] [
.B \-f
.I address_family
] [
.I system
] [
.I core
]
.br
.B netstat
[ 
.B \-himnrs
] [
.B \-f
.I address_family
] [
.I system
] [
.I core
]
.br
.B netstat
[ 
.B \-n
] [
.B \-I
.I interface
]
.I interval
[
.I system
] [
.I core
]
.br
.B netstat
[
.B \-I
.I interface
.B \-s
] [
.I system
] [
.I core
]
.SH Description
.NXR "netstat command"
.NXAM "network" "local area network"
.NXAM "network" "uucp utility"
.NXA "netstat command" "iostat command"
.NXA "netstat command" "vmstat command"
.NXR "network" "displaying status"
The
.PN netstat 
command displays the contents of network-related
data structures symbolically.
Depending on the options supplied to 
.PN netstat ,
there are a number of output formats.
.PP
The first form of the command displays a list of active sockets for each
protocol.  The second form presents the contents of one of the other network 
data structures according to the option selected.  The third form, with
an
.I interval
specified, 
continuously displays the information regarding packet traffic on the 
configured network interfaces.
The fourth form displays the Digital Network Architecture (DNA) Ethernet
Data Link Layer counters for an Ethernet interface,
or the DNA Fiber Distributed Data Interface (FDDI) Data Link Layer 
counters for an FDDI interface. It also presents 
the FDDI adapter's status and characteristics for the FDDI interface.  
.PP
If no options are specified,
.PN netstat 
displays the state of all active sockets from those using any of
the protocols listed in 
.PN /etc/protocols .
.PP
The arguments, 
.I system
and
.I core
allow substitutes for the defaults 
.PN /vmunix
and
.PN /dev/kmem .
.PP
If an 
.I interval
is specified,
.PN netstat
display the information regarding packet
traffic on the configured network interfaces continuously, pausing
.I interval
seconds before refreshing the screen.
.PP
There are a number of display formats, depending on the information
presented.  The default display, for active sockets, shows the local
and remote addresses, send and receive queue sizes (in bytes), protocol,
and, optionally, the internal state of the protocol.
.PP
Address formats are either of the form host.port or network.port,
if a socket's address specifies a network but no specific host address.
When known, the host and network addresses are displayed symbolically
according to the data bases 
.PN /etc/hosts
and 
.PN /etc/networks ,
respectively.  If a symbolic name for an address is unknown, or if
the 
.B \-n
option is specified,
the address is printed in the Internet dot format.
Refer to 
.MS inet 3n
for more information regarding this format.
Unspecified,
or wildcard, addresses and ports appear as an asterisk (*).
.PP
The interface display provides a table of cumulative
statistics regarding packets transferred, errors, and collisions.
.NXR "network" "interface display"
The network address (currently Internet specific) of the interface
and the maximum transmission unit (mtu) are also displayed.
.PP
The routing table display indicates the available routes and
their status.  
.NXR "network" "routing table display"
Each route consists of a destination host or network
and a gateway to use in forwarding packets.  The flags field shows
the state of the route (for example, U if up), whether the route
is to a gateway (G), and whether the route was created dynamically
by a redirect (D).  Direct routes are created for each
interface attached to the local host.
The gateway field for such entries shows the address of the outgoing
interface.
The refcnt field gives the
current number of active uses of the route.  Connection oriented
protocols normally hold on to a single route for the duration of
a connection, while connectionless protocols obtain a route while sending
to the same destination.  The use field provides a count
of the number of packets
sent using that route.  The interface entry indicates the network
interface utilized for the route.
.PP
When 
.PN netstat
is invoked with an
.I interval
argument, it displays a running count of statistics related to
network interfaces.
This display consists of a column for the primary interface (the first
interface found during autoconfiguration), and a column
summarizing information for all interfaces.
The primary interface may be replaced with another interface with the \-I
option.  The first line of each screen of information contains a summary
since the system was last rebooted.
Subsequent lines of output show values
accumulated over the preceding interval.
.SH Options
.NXR "netstat command" "options"
.IP \fB\-A\fR 20
Displays the address of any associated protocol control blocks; used
for debugging.
.IP \fB\-a\fR 20
Displays the information for all sockets.  Normally sockets used by
server processes are not shown.
.IP "\fB\-f \fIaddress_family\fR" 20
Limits statistics or address control block reports
to those of the specified
.I address family.
Recognized address families are
.I inet,
for AF_INET,
and
.I unix,
for AF_UNIX.
.IP \fB\-h\fR 20
Displays the state of the IMP host table.
.IP "\fB\-I \fIinterface\fR" 20
Shows information only about this interface.  Used with an 
.I interval
displayed below.
.IP "\fB\-I \fIinterface\fR -s" 20
Displays the DNA Ethernet Data Link Layer counters for an Ethernet interface.
Displays the DNA FDDI Data Link Layer counters, adapter's status and
characteristics for an FDDI interface. 
.IP \fB\-i\fR 20
Displays status information for autoconfigured interfaces .
Interfaces statically configured into a system, but not
located at boot time are not shown.
.IP \fB\-m\fR 20
Displays information for the memory management routines
The network manages a private share of memory.
.IP \fB\-n\fR 20
Displays network addresses as numbers.  Normally 
.PN netstat
interprets addresses and attempts to display them
symbolically.
.IP \fB\-r\fR 20
Displays the routing tables.  When \-s is also present, shows routing
statistics instead.
.IP \fB\-s\fR 20
Displays per-protocol statistics.
.IP \fB\-t\fR 20
Displays time until interface watchdog routine starts up
(used only in conjunction with
.B \-i
option).
.SH See Also
iostat(1), vmstat(1), hosts(5), networks(5), protocols(5),
services(5), trpt(8c)