NAME

netstat − show network status

SYNOPSIS

netstat [ −Aan | -an | -An | -Rn | -m | −i | -r | -rs | interval ] [ system [ core ] ]
(core is used by Series 800 computers only.) 

DESCRIPTION

The netstat command symbolically displays the contents of various network-related data structures. The information is displayed in various forms, depending on which options are specified. 

The default display for active sockets shows the local and remote addresses, send and receive queue sizes (in bytes), protocol, and, when applicable, the internal state of the protocol. Other display formats are controlled by the options listed below. 

−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. 

−R list a registry of all socket names;  returns NetIPC information, not BSD IPC information. 

−i show the state of the network interfaces and their attributes. 

−m show statistics recorded by the network 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). 

−s show per-protocol statistics.  Protocols listed are TCP, UDP, IP, ICMP, and PXP. 

−r show the gateway routing tables.  When used with the −s option, displays routing statistics. 

The arguments, system and core allow substitutes for the defaults “/hp-ux” and “/dev/kmem”.  The core argument is used by Series 800 computers only. 

If an interval is specified, netstat will continuously display the information regarding packet traffic on the configured network interfaces, pausing interval seconds before refreshing the screen. 

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 hosts(4) and networks(4), 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. 

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 through a gateway ( G ) or to a host ( H ).  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. 

WARNINGS

The notion of send/receive errors is ill-defined. 
 
Values for netstat statistics become negative when they reach 32,767. 

DEPENDENCIES

Implemented on the Series 300 and 800 only. 

Series 300 Only: The core argument is not supported. 

AUTHOR

UCB (University of California at Berkeley)

SEE ALSO

hosts(4), networks(4), protocols(4), services(4). 

Hewlett-Packard Company  —  May 11, 2021