NETSTAT(1)              NetBSD General Commands Manual              NETSTAT(1)

NAME
     netstat -- show network status

SYNOPSIS
     netstat [-Aan] [-f address_family] [-M core] [-N system]
     netstat [-bdgiLmnqrSsv] [-f address_family] [-M core] [-N system]
     netstat [-dn] [-I interface] [-M core] [-N system] [-w wait]
     netstat [-M core] [-N system] [-p protocol]
     netstat [-M core] [-N system] [-p protocol] -P pcbaddr
     netstat [-i] [-I Interface] [-p protocol]
     netstat [-is] [-f address_family] [-I Interface]
     netstat [-s] [-I Interface] -B

DESCRIPTION
     The netstat command symbolically displays the contents of various net-
     work-related data structures.  There are a number of output formats,
     depending on the options for the information presented.  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 struc-
     tures according to the option selected.  Using the third form, with a
     wait interval specified, netstat will continuously display the informa-
     tion regarding packet traffic on the configured network interfaces.  The
     fourth form displays statistics about the named protocol.  The fifth and
     sixth forms display per interface statistics for the specified protocol
     or address family.

     The options have the following meaning:

     -A    With the default display, show the address of any protocol control
           blocks associated with sockets; used for debugging.

     -a    With the default display, show the state of all sockets; normally
           sockets used by server processes are not shown.

     -B    With the default display, show the current bpf(4) peers.  To show
           only the peers listening to a specific interface, use the -I
           option.  If the -s option is present, show the current bpf(4) sta-
           tistics.

     -b    With the interface display (option -i), show bytes in and out,
           instead of packets in and out.

     -d    With either interface display (option -i or an interval, as
           described below), show the number of dropped packets.

     -f address_family
           Limit statistics or address control block reports to those of the
           specified address_family.  The following address families are rec-
           ognized: inet, for AF_INET; inet6, for AF_INET6; arp, for AF_ARP;
           ns, for AF_NS; iso, for AF_ISO; atalk, for AF_APPLETALK; and local
           or unix, for AF_LOCAL.

     -g    Show information related to multicast (group address) routing.  By
           default, show the IP Multicast virtual-interface and routing
           tables.  If the -s option is also present, show multicast routing
           statistics.

     -I interface
           Show information about the specified interface; used with a wait
           interval as described below.  If the -f address_family option (with
           the -s option) or the -p protocol option is present, show per-
           interface statistics on the interface for the specified
           address_family or protocol, respectively.

     -i    Show the state of interfaces which have been auto-configured
           (interfaces statically configured into a system, but not located at
           boot time are not shown).  If the -a options is also present, mul-
           ticast addresses currently in use are shown for each Ethernet
           interface and for each IP interface address.  Multicast addresses
           are shown on separate lines following the interface address with
           which they are associated.  If the -f address_family option (with
           the -s option) or the -p protocol option is present, show per-
           interface statistics on all interfaces for the specified
           address_family or protocol, respectively.

     -L    Don't show link-level routes (e.g., IPv4 ARP or IPv6 neighbour
           cache).

     -M    Extract values associated with the name list from the specified
           core instead of the default /dev/kmem.

     -m    Show statistics recorded by the memory management routines (the
           network manages a private pool of memory buffers).

     -N    Extract the name list from the specified system instead of the
           default /netbsd.

     -n    Show network addresses and ports as numbers (normally netstat
           interprets addresses and ports and attempts to display them symbol-
           ically).  This option may be used with any of the display formats.

     -P pcbaddr
           Dump the contents of the protocol control block (PCB) located at
           kernel virtual address pcbaddr.  This address may be obtained using
           the -A flag.  The default protocol is TCP, but may be overridden
           using the -p flag.

     -p protocol
           Show statistics about protocol, which is either a well-known name
           for a protocol or an alias for it.  Some protocol names and aliases
           are listed in the file /etc/protocols.  A null response typically
           means that there are no interesting numbers to report.  The program
           will complain if protocol is unknown or if there is no statistics
           routine for it.

     -q    Show software interrupt queue setting/statistics for all protocols.

     -r    Show the routing tables.  When -s is also present, show routing
           statistics instead.

     -S    Show network addresses as numbers (as with -n, but show ports sym-
           bolically).

     -s    Show per-protocol statistics.  If this option is repeated, counters
           with a value of zero are suppressed.

     -v    Show extra (verbose) detail for the routing tables (-r), or avoid
           truncation of long addresses.

     -w wait
           Show network interface statistics at intervals of wait seconds.

     The default display, for active sockets, 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 a socket's address specifies a net-
     work but no specific host address.  When known the host and network
     addresses are displayed symbolically according to the data bases
     /etc/hosts and /etc/networks, respectively.  If a symbolic name for an
     address is unknown, or if the -n option is specified, the address is
     printed numerically, according to the address family.  For more informa-
     tion regarding the Internet ``dot format,'' refer to inet(3)).  Unspeci-
     fied, or ``wildcard'', addresses and ports appear as ``*''.  You can use
     the fstat(1) command to find out which process or processes hold refer-
     ences to a socket.

     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 dis-
     played.

     The routing table display indicates the available routes and their sta-
     tus.  Each route consists of a destination host or network and a gateway
     to use in forwarding packets.  The flags field shows a collection of
     information about the route stored as binary choices.  The individual
     flags are discussed in more detail in the route(8) and route(4) manual
     pages.  The mapping between letters and flags is:

     1       RTF_PROTO1       Protocol specific routing flag #1
     2       RTF_PROTO2       Protocol specific routing flag #2
     B       RTF_BLACKHOLE    Just discard pkts (during updates)
     C       RTF_CLONING      Generate new routes on use
     c       RTF_CLONED       Cloned routes (generated from RTF_CLONING)
     D       RTF_DYNAMIC      Created dynamically (by redirect)
     G       RTF_GATEWAY      Destination requires forwarding by intermediary
     H       RTF_HOST         Host entry (net otherwise)
     L       RTF_LLINFO       Valid protocol to link address translation.
     M       RTF_MODIFIED     Modified dynamically (by redirect)
     R       RTF_REJECT       Host or net unreachable
     S       RTF_STATIC       Manually added
     U       RTF_UP           Route usable
     X       RTF_XRESOLVE     External daemon translates proto to link address

     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 pro-
     vides a count of the number of packets sent using that route.  The mtu
     entry shows the mtu associated with that route.  This mtu value is used
     as the basis for the TCP maximum segment size.  The 'L' flag appended to
     the mtu value indicates that the value is locked, and that path mtu dis-
     covery is turned off for that route.  A `-' indicates that the mtu for
     this route has not been set, and a default TCP maximum segment size will
     be used.  The interface entry indicates the network interface used for
     the route.

     When netstat is invoked with the -w option and a wait interval argument,
     it displays a running count of statistics related to network interfaces.
     An obsolescent version of this option used a numeric parameter with no
     option, and is currently supported for backward compatibility.  This dis-
     play 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 informa-
     tion contains a summary since the system was last rebooted.  Subsequent
     lines of output show values accumulated over the preceding interval.

     The first character of the flags column in the -B option shows the status
     of the bpf(4) descriptor which has three different values: Idle ('I'),
     Waiting ('W') and Timed Out ('T').  The second character indicates wheter
     the promisc flag is set.  The third character indicates the status of the
     immediate mode.  The fourth character indicates whether the peer will
     have the ability to see the packets sent.  And the fifth character shows
     the header complete flag status.

SEE ALSO
     fstat(1), nfsstat(1), ps(1), sockstat(1), vmstat(1), inet(3), bpf(4),
     hosts(5), networks(5), protocols(5), services(5), iostat(8), trpt(8)

HISTORY
     The netstat command appeared in 4.2BSD.  IPv6 support was added by
     WIDE/KAME project.

BUGS
     The notion of errors is ill-defined.

NetBSD 5.0_STABLE               August 30, 2007              NetBSD 5.0_STABLE
