NETSTAT(1N) COMMAND REFERENCE NETSTAT(1N) NAME netstat - show network status SYNOPSIS netstat [ -Aaimnrstu ] [ -a ] [ interval ] [ system ] [ core ] DESCRIPTION The netstat command symbolically displays the contents of various network-related data structures. OPTIONS -A show the address of any associated protocol control blocks; used for debugging -a show the state of all sockets; normally sockets used by server processes are not shown -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) -m show statistics recorded by the memory management routines (the network manages a ``private share'' of memory) -n show network addresses as numbers (normally netstat interprets addresses and attempts to display them symbolically) -r show the routing tables -s show per-protocol statistics; with -r, show routing statistics -t with -i, also show timer statistics -u show UNIXr domain socket information The arguments, system and core allow substitutes for the defaults /vmunix and /dev/kmem. If an interval is specified, netstat continuously displays the information regarding packet traffic on the configured network interfaces, pausing interval seconds before refreshing the screen. There are a number of display formats, depending on the information presented. The default display, for active sockets, shows the local and remote addresses, send and receive queue sizes (in bytes), protocol, and, optionally, the internal state of the protocol. Printed 5/12/88 1
NETSTAT(1N) COMMAND REFERENCE NETSTAT(1N) 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 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 in the Internet ``dot format''; refer to inet(3n) for more information regarding this format. Unspecified, or ``wildcard'' addresses and ports appear as ``*''. The interface display provides a table of cumulative statistics regarding packets transferred, errors, and collisions. The network address (currently Internet specific) of the interface and the maximum transmission unit (``mtu'') are also displayed. Additionally specifying the -t option causes watchdog timer statistics to be included in the interface display. The routing table display indicates the available routes and their status. Each route consists of a destination host or network and a gateway to use in forwarding packets. The flags field shows the state of the route (``U'' if ``up''), and whether the route is to a gateway (``G''). Direct routes are created for each interface attached to the local host. 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, then discard it. The use field provides a count of the number of packets sent using that route. The interface entry indicates the network interface utilized for the route. When netstat is invoked with an interval argument, it displays a running count of statistics related to network interfaces. This display consists of a column summarizing information for all interfaces, and a column for the interface with the most traffic since the system was last rebooted. 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. RETURN VALUE [USAGE] Incorrect command line syntax. Execution terminated. [P_ERR] A system error occurred. Execution terminated. See intro(2) for more information on system errors. [INTERNAL] An unexpected error occurred. Execution was Printed 5/12/88 2
NETSTAT(1N) COMMAND REFERENCE NETSTAT(1N) terminated. Record the message and save the core file for analysis. Contact service personnel at your Tektronix field office. [P_WARN] A system error occurred. Execution continues. See intro(2) for more information on system errors. [NP_WARN] An error warranting a warning message occurred. Execution continues. [NP_ERR] An error occurred that was not a system error. Execution terminated. CAVEATS The notion of errors is ill-defined. Collisions mean something else for the IMP. SEE ALSO iostat(1), vmstat(1), hosts(5n), networks(5n), protocols(5n), and services(5n). Printed 5/12/88 3
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