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32 .\" @(#)netstat.1 8.8 (Berkeley) 4/18/94
33 .\"
34 .Dd April 18, 1994
35 .Dt NETSTAT 1
36 .Os BSD 4.2
37 .Sh NAME
38 .Nm netstat
39 .Nd show network status
40 .Sh SYNOPSIS
41 .Nm netstat
42 .Op Fl Aan
43 .Op Fl f Ar address_family
44 .Op Fl M Ar core
45 .Op Fl N Ar system
46 .Nm netstat
47 .Op Fl bdghimnrs
48 .Op Fl f Ar address_family
49 .Op Fl M Ar core
50 .Op Fl N Ar system
51 .Nm netstat
52 .Op Fl bdn
53 .Op Fl I Ar interface
54 .Op Fl M Ar core
55 .Op Fl N Ar system
56 .Op Fl w Ar wait
57 .Nm netstat
58 .Op Fl p Ar protocol
59 .Op Fl M Ar core
60 .Op Fl N Ar system
61 .Sh DESCRIPTION
62 The
63 .Nm netstat
64 command symbolically displays the contents of various network-related
65 data structures.
66 There are a number of output formats,
67 depending on the options for the information presented.
68 The first form of the command displays a list of active sockets for
69 each protocol.
70 The second form presents the contents of one of the other network
71 data structures according to the option selected.
72 Using the third form, with a
73 .Ar wait
74 interval specified,
75 .Nm netstat
76 will continuously display the information regarding packet
77 traffic on the configured network interfaces.
78 The fourth form displays statistics about the named protocol.
79 .Pp
80 The options have the following meaning:
81 .Bl -tag -width flag
82 .It Fl A
83 With the default display,
84 show the address of any protocol control blocks associated with sockets; used
85 for debugging.
86 .It Fl a
87 With the default display,
88 show the state of all sockets; normally sockets used by
89 server processes are not shown.
90 .It Fl b
91 With either interface display (option
92 .Fl i
93 or an interval, as described below),
94 show the number of bytes in and out.
95 .It Fl d
96 With either interface display (option
97 .Fl i
98 or an interval, as described below),
99 show the number of dropped packets.
100 .It Fl f Ar address_family
101 Limit statistics or address control block reports to those
102 of the specified
103 .Ar address family .
104 The following address families
105 are recognized:
106 .Ar inet ,
107 for
108 .Dv AF_INET ,
109 .Ar ns ,
110 for
111 .Dv AF_NS ,
112 .Ar iso ,
113 for
114 .Dv AF_ISO ,
115 and
116 .Ar unix ,
117 for
118 .Dv AF_UNIX .
119 .It Fl g
120 Show information related to multicast (group address) routing.
121 By default, show the IP Multicast virtual-interface and routing tables.
122 If the
123 .Fl s
124 option is also present, show multicast routing statistics.
125 .It Fl h
126 Show the state of the
127 .Tn IMP
128 host table (obsolete).
129 .It Fl I Ar interface
130 Show information about the specified interface;
131 used with a
132 .Ar wait
133 interval as described below.
134 .It Fl i
135 Show the state of interfaces which have been auto-configured
136 (interfaces statically configured into a system, but not
137 located at boot time are not shown).
138 If the
139 .Fl a
140 options is also present, multicast addresses currently in use are shown
141 for each Ethernet interface and for each IP interface address.
142 Multicast addresses are shown on separate lines following the interface
143 address with which they are associated.
144 .It Fl M
145 Extract values associated with the name list from the specified core
146 instead of the default
147 .Pa /dev/kmem .
148 .It Fl m
149 Show statistics recorded by the memory management routines
150 (the network manages a private pool of memory buffers).
151 .It Fl N
152 Extract the name list from the specified system instead of the default
153 .Pa /kernel .
154 .It Fl n
155 Show network addresses as numbers (normally
156 .Nm netstat
157 interprets addresses and attempts to display them
158 symbolically).
159 This option may be used with any of the display formats.
160 .It Fl p Ar protocol
161 Show statistics about
162 .Ar protocol ,
163 which is either a well-known name for a protocol or an alias for it. Some
164 protocol names and aliases are listed in the file
165 .Pa /etc/protocols .
166 A null response typically means that there are no interesting numbers to
167 report.
168 The program will complain if
169 .Ar protocol
170 is unknown or if there is no statistics routine for it.
171 .It Fl s
172 Show per-protocol statistics.
173 If this option is repeated, counters with a value of zero are suppressed.
174 .It Fl r
175 Show the routing tables.
176 When
177 .Fl s
178 is also present, show routing statistics instead.
179 .It Fl w Ar wait
180 Show network interface statistics at intervals of
181 .Ar wait
182 seconds.
183 .El
184 .Pp
185 The default display, for active sockets, shows the local
186 and remote addresses, send and receive queue sizes (in bytes), protocol,
187 and the internal state of the protocol.
188 Address formats are of the form ``host.port'' or ``network.port''
189 if a socket's address specifies a network but no specific host address.
190 When known the host and network addresses are displayed symbolically
191 according to the data bases
192 .Pa /etc/hosts
193 and
194 .Pa /etc/networks ,
195 respectively. If a symbolic name for an address is unknown, or if
196 the
197 .Fl n
198 option is specified, the address is printed numerically, according
199 to the address family.
200 For more information regarding
201 the Internet ``dot format,''
202 refer to
203 .Xr inet 3 ) .
204 Unspecified,
205 or ``wildcard'', addresses and ports appear as ``*''.
206 .Pp
207 The interface display provides a table of cumulative
208 statistics regarding packets transferred, errors, and collisions.
209 The network addresses of the interface
210 and the maximum transmission unit (``mtu'') are also displayed.
211 .Pp
212 The routing table display indicates the available routes and
213 their status. Each route consists of a destination host or network
214 and a gateway to use in forwarding packets. The flags field shows
215 a collection of information about the route stored as
216 binary choices. The individual flags are discussed in more
217 detail in the
218 .Xr route 8
219 and
220 .Xr route 4
221 manual pages.
222 The mapping between letters and flags is:
223 .Bl -column XXXX RTF_BLACKHOLE
224 1 RTF_PROTO2 Protocol specific routing flag #1
225 2 RTF_PROTO1 Protocol specific routing flag #2
226 3 RTF_PROTO3 Protocol specific routing flag #3
227 B RTF_BLACKHOLE Just discard pkts (during updates)
228 C RTF_CLONING Generate new routes on use
229 c RTF_PRCLONING Protocol-specified generate new routes on use
230 D RTF_DYNAMIC Created dynamically (by redirect)
231 G RTF_GATEWAY Destination requires forwarding by intermediary
232 H RTF_HOST Host entry (net otherwise)
233 L RTF_LLINFO Valid protocol to link address translation
234 M RTF_MODIFIED Modified dynamically (by redirect)
235 R RTF_REJECT Host or net unreachable
236 S RTF_STATIC Manually added
237 U RTF_UP Route usable
238 W RTF_WASCLONED Route was generated as a result of cloning
239 X RTF_XRESOLVE External daemon translates proto to link address
240 .El
241 .Pp
242 Direct routes are created for each
243 interface attached to the local host;
244 the gateway field for such entries shows the address of the outgoing interface.
245 The refcnt field gives the
246 current number of active uses of the route. Connection oriented
247 protocols normally hold on to a single route for the duration of
248 a connection while connectionless protocols obtain a route while sending
249 to the same destination.
250 The use field provides a count of the number of packets
251 sent using that route. The interface entry indicates the network
252 interface utilized for the route.
253 .Pp
254 When
255 .Nm netstat
256 is invoked with the
257 .Fl w
258 option and a
259 .Ar wait
260 interval argument, it displays a running count of statistics related to
261 network interfaces.
262 An obsolescent version of this option used a numeric parameter
263 with no option, and is currently supported for backward compatibility.
264 This display consists of a column for the primary interface (the first
265 interface found during autoconfiguration) and a column summarizing
266 information for all interfaces.
267 The primary interface may be replaced with another interface with the
268 .Fl I
269 option.
270 The first line of each screen of information contains a summary since the
271 system was last rebooted. Subsequent lines of output show values
272 accumulated over the preceding interval.
273 .Sh SEE ALSO
274 .Xr iostat 1 ,
275 .Xr nfsstat 1 ,
276 .Xr ps 1 ,
277 .Xr vmstat 1 ,
278 .Xr hosts 5 ,
279 .Xr networks 5 ,
280 .Xr protocols 5 ,
281 .Xr services 5 ,
282 .Xr trpt 8 ,
283 .Xr trsp 8
284 .Sh HISTORY
285 The
286 .Nm netstat
287 command appeared in
288 .Bx 4.2 .
289 .\" .Sh FILES
290 .\" .Bl -tag -width /dev/kmem -compact
291 .\" .It Pa /kernel
292 .\" default kernel namelist
293 .\" .It Pa /dev/kmem
294 .\" default memory file
295 .\" .El
296 .Sh BUGS
297 The notion of errors is ill-defined.