hpux 10.20 - netstat (1)
NAME
netstat - show network status
SYNOPSIS
netstat [-aAn] [-f address-family] [system [core]]
netstat [-mMnrsv] [-f address-family] [-p protocol] [system [core]]
netstat [-gin] [-I interface] [interval] [system [core]]
DESCRIPTION
netstat displays statistics for network interfaces and protocols, as
well as the contents of various network-related data structures. The
output format varies according to the options selected. Some options
are ignored when used in combination with other options.
Generally, the netstat command takes one of the three forms shown
above:
+ The first form of the command displays a list of active
sockets for each protocol.
+ The second form displays the contents of one of the other
network data structures according to the option selected.
+ The third form displays configuration information for each
network interface. It also displays network traffic data on
configured network interfaces, optionally updated at each
interval, measured in seconds.
Options are interpreted as follows:
-a Show the state of all sockets, including
passive sockets used by server processes. When
netstat is used without any options (except -A
and -n), only active sockets are shown. This
option does not show the state of X.25
programmatic access sockets. The option is
ignored if the -g, -i, -I, -m, -M, -p, -r, -s
or interval option is specified.
-A Show the address of the protocol control block
associated with sockets. This option is used
for debugging. It does not show the X.25
programmatic access control blocks. This
option is ignored if the -g, -i, -I, -m, -M,
-p, -r, -s or interval option is specified.
-f address-family Show statistics or address control block for
only the specified address-family. The
following address families are recognized: inet
for AF_INET, and unix for AF_UNIX. This option
applies to the -a, -A and -s options.
-g Show multicast information for network
interfaces. Only the address family AF_INET is
recognized by this option. This option may be
combined with the -i option to display both
kinds of information. The option is ignored if
the -m, -M or -p option is specified.
-i Show the state of network interfaces.
Interfaces that are statically configured into
a system, but not located at boot time, are not
shown. This option is ignored if the -m, -M or
-p option is specified.
-I interface Show information about the specified interface
only. This option applies to the -g and -i
options.
-m Show statistics recorded by network memory
management routines. If this option is
specified, all other options are ignored.
-M Show the multicast routing tables. When -s is
used with the -M option, netstat displays
multicast routing statistics instead. This
option is ignored if the -m or -p option is
specified.
-n Show network addresses as numbers. Normally,
netstat interprets addresses and attempts to
display them symbolically. This option applies
to the -a, -A, -i, -r and -v options.
-p protocol Show statistics for the specified protocol.
The following protocols are recognized: tcp,
udp, ip, icmp, igmp, arp, and probe. This
option is ignored if the -m option is
specified.
-r Show the routing tables. When -v is used with
the -r option, netstat also displays the
network masks in the route entries. When -s is
used with the -r option, netstat displays
routing statistics instead. This option is
ignored if the -g, -m, -M, -i, -I, -p or
interval option is specified.
-s Show statistics for all protocols. When this
option is used with the -r option, netstat
displays routing statistics instead. When this
option is used with the -M option, netstat
displays multicast routing statistics instead.
This option is ignored if the -g, -i, -I, -m,
-p or interval option is specified.
-v Show additional routing information. When -v
is used with the -r option, netstat also
displays the network masks in the route
entries. This option only applies to the -r
option.
The arguments system and core allow substitutes for the defaults,
/stand/vmunix and /dev/kmem.
If no options or only the -A or -n option is specified, netstat
displays the status of only active sockets. The display of active and
passive sockets status shows the local and remote addresses, send and
receive queue sizes (in bytes), protocol, and the internal state of
the protocol. Address formats are of the form host.port, or
network.port if the host portion of a socket address is zero. When
known, the host and network addresses are displayed symbolically by
using gethostbyname() and getnetbyname(), respectively (see
gethostbyname(3N) and getnetbyname(3N)). If a symbolic name for an
address is unknown, or if the -n option is specified, the address is
displayed numerically according to the address family. For more
information regarding the Internet ``dot format'', refer to inet(3N).
Unspecified or ``wildcard'' addresses and ports appear as an asterisk
(*).
The interface display provides a table of cumulative statistics
regarding packets transferred, errors, and collisions. The network
addresses of the interface and the maximum transmission unit (MTU) are
also displayed. When the interval argument is specified, netstat
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 auto-configuration) and a column summarizing
information for all interfaces. To replace the primary interface with
another interface, use 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.
The routing table display indicates the available routes and their
status. Each route consists of a destination host or network, a
netmask and a gateway to use in forwarding packets. The Flags field
shows whether the route is up (U), whether the route is to a gateway
(G), whether the route is a host or network route (with or without H),
whether the route was created dynamically (D) by a redirect or by Path
MTU Discovery, and whether a gateway route has been modified (M), or
it has been marked doubtful (?) due to the lack of a timely ARP
response.
The Netmask field shows the mask to be applied to the destination IP
address of an IP packet to be forwarded. The result will be compared
with the destination address in the route entry. If they are the same,
then the route is one of the candidates for routing this IP packet.
If there are several candidate routes, then the route with the longest
Netmask field (contiguous 1's starting from the leftmost bit position)
will be chosen. (see routing (7).)
The Gateway field shows the address of the immediate gateway for
reaching the destination. It can be the address of the outgoing
interface if the destination is on a directly connected network.
The Refs field shows 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 normally
obtain a route just while sending a particular message. The Use field
shows a count of the number of packets sent using the route. The
Interface field identifies which network interface is used for the
route.
The Pmtu and PmtuTime fields apply only to host routes. The Pmtu
field for network and default routes is the same as the MTU of the
network interface used for the route. If the route is created with a
static PMTU value (see route(1M)), the corresponding PmtuTime field
contains the word perm, and the PMTU value permanently overrides the
interface MTU. If the route is created dynamically (D in the Flags
field), the value in the corresponding PmtuTime field is the number of
minutes remaining before the PMTU expires. When the PMTU expires, the
system rediscovers the current PMTU for the route, in case it has
changed. The PmtuTime field is left blank when the PMTU is identical
to the MTU of the interface. An asterisk (*) in the Pmtu field
indicates that user has disabled the PMTU Discovery for the route.
DEPENDENCIES
X.25:
-A and -a options do not list X.25 programmatic access information.
AUTHOR
netstat was developed by the University of California, Berkeley.
SEE ALSO
hosts(4), networks(4), gethostbyname(3N), getnetbyname(3N),
protocols(4), route(1M), services(4).