1NETSTAT(1) General Commands Manual NETSTAT(1)
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6 netstat - show network status
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9 netstat [ -Aan ] [ -f address_family ] [ system ] [ core ]
10 netstat [ -himnrs ] [ -f address_family ] [ system ] [ core ]
11 netstat [ -n ] [ -I interface ] interval [ system ] [ core ]
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14 The netstat command symbolically displays the contents of various net‐
15 work-related data structures. There are a number of output formats,
16 depending on the options for the information presented. The first form
17 of the command displays a list of active sockets for each protocol.
18 The second form presents the contents of one of the other network data
19 structures according to the option selected. Using the third form,
20 with an interval specified, netstat will continuously display the
21 information regarding packet traffic on the configured network inter‐
22 faces.
23 The options have the following meaning:
25 -A With the default display, show the address of any protocol con‐
27 trol blocks associated with sockets; used for debugging.
28 -a With the default display, show the state of all sockets; nor‐
30 mally sockets used by server processes are not shown.
31 -h Show the state of the IMP host table.
33 -i Show the state of interfaces which have been auto-configured
35 (interfaces statically configured into a system, but not located
36 at boot time are not shown).
37 -I interface
39 Show information only about this interface; used with an inter‐
40 val as described below.
41 -m Show statistics recorded by the memory management routines (the
43 network manages a private pool of memory buffers).
44 -n Show network addresses as numbers (normally netstat interprets
46 addresses and attempts to display them symbolically). This
47 option may be used with any of the display formats.
48 -s Show per-protocol statistics.
50 -r Show the routing tables. When -s is also present, show routing
52 statistics instead.
53 -f address_family
55 Limit statistics or address control block reports to those of
56 the specified address family. The following address families
57 are recognized: inet, for AF_INET, ns, for AF_NS, and unix, for
58 AF_UNIX.
59 The arguments, system and core allow substitutes for the defaults
61 ``/vmunix'' and ``/dev/kmem''.
62 The default display, for active sockets, shows the local and remote
64 addresses, send and receive queue sizes (in bytes), protocol, and the
65 internal state of the protocol. Address formats are of the form
66 ``host.port'' or ``network.port'' if a socket's address specifies a
67 network but no specific host address. When known the host and network
68 addresses are displayed symbolically according to the data bases
69 /etc/hosts and /etc/networks, respectively. If a symbolic name for an
70 address is unknown, or if the -n option is specified, the address is
71 printed numerically, according to the address family. For more infor‐
72 mation regarding the Internet ``dot format,'' refer to inet(3N).
73 Unspecified, or ``wildcard'', addresses and ports appear as ``*''.
74 The interface display provides a table of cumulative statistics regard‐
76 ing packets transferred, errors, and collisions. The network addresses
77 of the interface and the maximum transmission unit (``mtu'') are also
78 displayed.
79 The routing table display indicates the available routes and their sta‐
81 tus. Each route consists of a destination host or network and a gate‐
82 way to use in forwarding packets. The flags field shows the state of
83 the route (``U'' if ``up''), whether the route is to a gateway (``G''),
84 and whether the route was created dynamically by a redirect (``D'').
85 Direct routes are created for each interface attached to the local
86 host; the gateway field for such entries shows the address of the out‐
87 going interface. The refcnt field gives the current number of active
88 uses of the route. Connection oriented protocols normally hold on to a
89 single route for the duration of a connection while connectionless pro‐
90 tocols obtain a route while sending to the same destination. The use
91 field provides a count of the number of packets sent using that route.
92 The interface entry indicates the network interface utilized for the
93 route.
94 When netstat is invoked with an interval argument, it displays a run‐
96 ning count of statistics related to network interfaces. This display
97 consists of a column for the primary interface (the first interface
98 found during autoconfiguration) and a column summarizing information
99 for all interfaces. The primary interface may be replaced with another
100 interface with the -I option. The first line of each screen of infor‐
101 mation contains a summary since the system was last rebooted. Subse‐
102 quent lines of output show values accumulated over the preceding inter‐
103 val.
104
106 iostat(1), vmstat(1), hosts(5), networks(5), protocols(5), services(5),
107 trpt(8C)
108
110 The notion of errors is ill-defined. Collisions mean something else
111 for the IMP.
1124.2 Berkeley Distribution May 8, 1986 NETSTAT(1)