netstat(1N) netstat(1N)NAME netstat - displays network status information SYNOPSIS netstat [-a] [-A] [-n] [-f address-family] [kernel] [memory-interface] netstat [-h] [-i] [-m] [-n] [-r] [-s] [-f address-family] [kernel] [memory-interface] netstat [-I interface] interval [kernel] [memory-interface] netstat -I interface [-n] [kernel] [memory-interface] ARGUMENTS -a Displays the state of all sockets, including sockets that are used by server processes, using the default display. -A Displays the address of any protocol control blocks associated with sockets as well as the default display. This option is used for debugging. -f address-family Limits the display of statistics or address control blocks to those specified by the value of address-family. You can use these address families: inet (for AF_INET) and unix (for AF_UNIX). -h Displays the state of the ICMP host table, using the default display. -i Displays the state of interfaces that have been configured into the kernel by autoconfig. Interfaces statically configured into the system but not assigned at the time the system starts up are not shown. -I interface Displays information about the interface specified by interface only. Possible values for interface include ae0, lo0, sl0, and sl1. interval Specifies, in seconds, an interval of time during which netstat accumulates and displays data continuously for the default interface, which is the first interface that autoconfig configured when it made the kernel. kernel Specifies a kernel other than the default, /unix. -m Displays statistics recorded by the memory-management January 1992 1
netstat(1N) netstat(1N)routines that manage a private pool of memory buffers. memory-interface Specifies a memory interface other than the default, /dev/kmem. -n Causes netstat to display Internet addresses as numbers. If you do not specify this option, netstat interprets addresses and displays them symbolically. You can use this option with any option that causes the display of an Internet address. -r Displays the routing tables. If you also specify the -s option, the -r option displays routing statistics instead. -s Displays statistics on a per-protocol basis. The available protocols include UDP, TCP, ICMP, and IP. DESCRIPTION netstat displays the contents of various network-related data structures in the kernel, including the active sockets for each protocol, interface information, and packet traffic. Default Display When the netstat command is given with no options or with the -a, -A, or -h option, netstat uses its default display to present the resulting information for all sockets except those sockets used by server processes. The information includes the name of the protocol, the size of the send queue and the size of the receive queue in bytes, the local and remote addresses, and the internal state of the protocol. This format is the default display. If a socket's address specifies a network but no specific host address, address formats are of the form host.port or network.port. When the host and network addresses are known, netstat displays them symbolically according to /etc/hosts and /etc/networks, respectively. If a symbolic name for an address is unknown or if you specify the -n option, netstat displays the address numerically according to the address family. For more information on the format of Internet addresses, see inet(3N). An unspecified or wildcard address or port appears as an asterick (*). Routing Table Display Use the -r option to show 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''), whether the route is to a gateway (G), and whether the route was created dynamically by a redirect (D). Direct routes 2 January 1992
netstat(1N) netstat(1N)are created for each interface attached to the local host; the Gateway field for such entries shows the address of the outgoing interface. The Ref field gives the current number of active uses of the route. Connection-oriented protocols usually preserve a single route for the duration of a connection, whereas connectionless protocols obtain a route while sending to the same destination. The Use field provides a count of the number of packets sent over that route. The Interface field indicates the network interface used for the route. Memory Statistics Display Use the -m option to show the number of buffers allocated to packet headers, socket structures, protocol control blocks, routing table entries, socket names and addresses, and interface addresses. The output also includes a summary of mapped pages in use, allocated interface pages, requests for memory delayed or denied, and the number of calls to the protocol drain routines. Interface Display Use the -i or -I option to show interface information. The Mtu field gives the maximum transmission unit of the interface. The Ipkts and Opkts fields give, respectively, the number of incoming and outgoing packets transmitted since the system was started. The Ierrs and Oerrs fields give, respectively, the number of incoming and outgoing errors that have occurred since the system was started. The Coll field gives the number of collisions that have occurred since the system was started. Protocol Display Use the -s option to produce a summary of protocol-specific information. For example, the output for the UDP protocol includes the number of incomplete headers, the number of bad data-length fields, the number of bad checksums, the number of received packets, the number of received big packets, and the number of socket overflows. Interval Display If you specify the interval argument, netstat displays five columns of summary information about the default interface since the system was started and five columns of summary information about all interfaces. Subsequent lines of output show values accumulated over the preceding interval. To stop the output, send an interrupt signal (SIGINT), usually CONTROL-C, to netstat. You can change the default interface by using the -I option. LIMITATIONS The notion of errors is ill-defined. January 1992 3
netstat(1N) netstat(1N)Collisions have a different meaning in the ICMP protocol than in the other protocols. FILES /dev/kmem Default memory interface file /unix Default kernel directory /usr/bin/netstat Executable file SEE ALSO hosts(4), networks(4N), protocols(4N), services(4N) in A/UX Programmer's Reference trpt(1M) in A/UX System Administrator's Reference 4 January 1992