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netstat(1)

NAME

     netstat -- show network status

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.

     netstat [-AaLnSW] [-f protocol_family | -p protocol] [-M core]
	     [-N system]
	     Display a list of active sockets (protocol control blocks) for
	     each network protocol, for a particular protocol_family, or for a
	     single protocol.  If -A is also present, show the address of a
	     protocol control block (PCB) associated with a socket; used for
	     debugging.  If -a is also present, show the state of all sockets;
	     normally sockets used by server processes are not shown.  If -L
	     is also present, show the size of the various listen queues.  The
	     first count shows the number of unaccepted connections, the sec-
	     ond count shows the amount of unaccepted incomplete connections,
	     and the third count is the maximum number of queued connections.
	     If -S is also present, show network addresses as numbers (as with
	     -n) but show ports symbolically.

     netstat -i | -I interface [-abdnt] [-f address_family] [-M core]
	     [-N system]
	     Show the state of all network interfaces or a single interface
	     which have been auto-configured (interfaces statically configured
	     into a system, but not located at boot time are not shown).  An
	     asterisk (``*'') after an interface name indicates that the
	     interface is ``down''.  If -a is also present, multicast
	     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 -b is also present, show the number of bytes
	     in and out.  If -d is also present, show the number of dropped
	     packets.  If -t is also present, show the contents of watchdog
	     timers.  If -W is also present, print interface names using a
	     wider field size.

     netstat -w wait [-I interface] [-d] [-M core] [-N system]
	     At intervals of wait seconds, display the information regarding
	     packet traffic on all configured network interfaces or a single
	     interface.  If -d is also present, show the number of dropped
	     packets.

     netstat -s [-s] [-z] [-f protocol_family | -p protocol] [-M core]
	     [-N system]
	     Display system-wide statistics for each network protocol, for a
	     particular protocol_family, or for a single protocol.  If -s is
	     repeated, counters with a value of zero are suppressed.  If -z is
	     also present, reset statistic counters after displaying them.

     netstat -i | -I interface -s [-f protocol_family | -p protocol] [-M core]
	     [-N system]
	     Display per-interface statistics for each network protocol, for a
	     particular protocol_family, or for a single protocol.

	     debugging.  If -a is also present, show protocol-cloned routes
	     (routes generated by an RTF_PRCLONING parent route); normally
	     these routes are not shown.  When -W is also present, show the
	     path MTU for each route, and print interface names with a wider
	     field size.

     netstat -rs [-s] [-M core] [-N system]
	     Display routing statistics.  If -s is repeated, counters with a
	     value of zero are suppressed.

     netstat -g [-W] [-f address_family] [-M core] [-N system]
	     Show information related to multicast (group address) routing.
	     By default, show the IP Multicast virtual-interface and routing
	     tables, and multicast group memberships.

     netstat -gs [-s] [-f address_family] [-M core] [-N system]
	     Show multicast routing statistics.  If -s is repeated, counters
	     with a value of zero are suppressed.

     Some options have the general meaning:

     -f address_family, -p protocol
	   Limit display to those records of the specified address_family or a
	   single protocol.  The following address families and protocols are
	   recognized:

	   Family		       Protocols
	   inet (AF_INET)	       bdg, divert, icmp, igmp, ip, ipsec,
				       pim, tcp, udp
	   inet6 (AF_INET6)	       bdg, icmp6, ip6, ipsec6, rip6, tcp, udp
	   pfkey (PF_KEY)	       pfkey
	   atalk (AF_APPLETALK)        ddp
	   netgraph, ng (AF_NETGRAPH)  ctrl, data
	   ipx (AF_IPX) 	       ipx, spx
	   unix (AF_UNIX)
	   link (AF_LINK)

	   The program will complain if protocol is unknown or if there is no
	   statistics routine for it.

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

     -N    Extract the name list from the specified system instead of the
	   default, which is the kernel image the system has booted from.

     -n    Show network addresses and ports as numbers.  Normally netstat
	   attempts to resolve addresses and ports, and display them symboli-
	   cally.

     -W    In certain displays, avoid truncating addresses even if this causes
	   some fields to overflow.

     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
     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
     3	  RTF_PROTO3	   Protocol specific routing flag #3
     B	  RTF_BLACKHOLE    Just discard pkts (during updates)
     b	  RTF_BROADCAST    The route represents a broadcast address
     C	  RTF_CLONING	   Generate new routes on use
     c	  RTF_PRCLONING    Protocol-specified generate new routes on use
     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
     W	  RTF_WASCLONED    Route was generated as a result of cloning
     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 inter-
     face 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.  By
     default, this display summarizes information for all interfaces.  Infor-
     mation for a specific interface may be displayed with the -I option.

SEE ALSO

     fstat(1), nfsstat(1), ps(1), sockstat(1), inet(4), route(4), unix(4),
     hosts(5), networks(5), protocols(5), services(5), iostat(8), route(8),
     trpt(8), vmstat(8), mbuf(9)

HISTORY

     The netstat command appeared in 4.2BSD.

     IPv6 support was added by WIDE/KAME project.

BUGS

     The notion of errors is ill-defined.

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