Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
NETSTAT(1)                 OpenBSD Reference Manual                 NETSTAT(1)

     netstat - show network status

     netstat [-Aan] [-f address_family] [-M core] [-N system]
     netstat [-bdgilmnqrstu] [-f address_family] [-M core] [-N system]
     netstat [-bdn] [-I interface] [-M core] [-N system] [-w wait]
     netstat [-M core] [-N system] [-p protocol]
     netstat [-s] [-f address_family] [-i] [-I Interface]

     The netstat command symbolically displays the contents of various net-
     work-related data structures.  There are a number of output formats, de-
     pending 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 net-
     work data structures according to the option selected.  Using the third
     form, with a wait interval specified, netstat will continuously display
     the information regarding packet traffic on the configured network inter-
     faces.  The fourth form displays statistics about the named protocol.
     The fifth form displays per interface statistics for the specified ad-
     dress family.

     The options are as follows:

     -A      With the default display, show the address of any protocol con-
             trol 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 interface display (option -i), show bytes in and out,
             instead of packet statistics.

     -d      With either interface display (option -i or an interval, as de-
             scribed 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 recognized:

                   Address Family    Constant      Description
                   inet              AF_INET       IP Version 4
                   inet6             AF_INET6      IP Version 6
                   ipx               AF_IPX        Novell IPX
                   atalk             AF_APPLETALK  AppleTalk
                   ns                AF_NS         Xerox NS Protocols
                   iso               AF_ISO        ISO Protocol Family
                   encap             PF_KEY        IPsec
                   local             AF_LOCAL      Local to Host (i.e., pipes)
                   unix              AF_UNIX       Local to Host (i.e., pipes)

     -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

     -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) is present,
             show per-interface statistics on the given interface for the
             specified address_family.

     -i      Show the state of interfaces which have been auto-configured (in-
             terfaces statically configured into a system but not located at
             boot-time are not shown).

             If the -a option is also present, multicast addresses currently
             in use are shown for each Ethernet interface and for each IP in-
             terface 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) is present,
             show per-interface statistics on all interfaces for the specified

     -l      With the -g option, display wider fields for the IPv6 multicast
             routing table "Origin" and "Group" columns.

     -M core
             Extract values associated with the name list from the specified
             core instead of the running kernel.

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

     -N system
             Extract the name list from the specified system instead of the
             running kernel.

     -n      Show network addresses as numbers (normally netstat interprets
             addresses and attempts to display them symbolically).  This op-
             tion may be used with any of the display formats.

     -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      Only show interfaces that have seen packets (or bytes if -b is

     -r      Show the routing tables.  If the -s option is also specified,
             show routing statistics instead.

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

     -t      With the -i option, display the current value of the watchdog
             timer function.

     -u      Limit statistics or address control block reports to the AF_UNIX
             address family.

     -v      Be verbose.  Avoids 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 ad-
     dresses, send and receive queue sizes (in bytes), protocol, and the in-
     ternal state of the protocol.

     Address formats are 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 accord-
     ing to the databases /etc/hosts and /etc/networks, respectively.  If a
     symbolic name for an address is unknown, or if the -n option is speci-
     fied, the address is printed numerically, according to the address fami-

     For more information regarding the Internet ``dot format'', refer to
     inet(3).  Unspecified, or ``wildcard'' addresses and ports appear as a
     single ``*''.  If a local port number is registered as being in use for
     RPC by portmap(8), its RPC service name or RPC service number will be
     printed in ``[]'' immediately after the port number.

     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.

     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.  If the destination is a network in numeric
     format, the netmask (in /24 style format) is appended.  The flags field
     shows a collection of information about the route stored as binary choic-
     es.  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.
     3       RTF_PROTO3       Protocol specific routing flag #3.
     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 in-
     terface.  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 MTU entry
     shows the MTU associated with that route.  This MTU value is used as the
     basis for the TCP maximum segment size (MSS).  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 utilized
     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 in-
     terface 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.

     nfsstat(1), ps(1), netintro(4), hosts(5), networks(5), protocols(5),
     services(5), iostat(8), trpt(8), vmstat(8)

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

     The notion of errors is ill-defined.

OpenBSD 3.4                     April 18, 1994                               4


Want to link to this manual page? Use this URL:

home | help