snmpnetstat will issue GETBULK requests to query for information if at least protocol version v2 is used.
AGENT identifies a target SNMP agent, which is instrumented to monitor the given objects. At its simplest, the AGENT specification will consist of a hostname or an IPv4 address. In this situation, the command will attempt communication with the agent, using UDP/IPv4 to port 161 of the given target host. See snmpcmd(1) for a full list of the possible formats for AGENT.
Please see snmpcmd(1) for a list of possible values for common options as well as their descriptions.
-CL use the legacy SNMP MIB elements, not the modern IP version agnostic tables. snmpnetstat will automatically fall back to the legacy tables if the modern ones are not available.
-Ca With the default display, show the state of all sockets; normally sockets used by server processes are not shown.
-Cf address_family Only show entries for the selected address family (inet, inet6)
-Ci Show the state of all of the network interfaces. The interface display provides a table of cumulative statistics regarding packets transferred, errors, and collisions. The network addresses of the interface and the maximum transmission unit (``mtu'') are also displayed.
-Cd Add dropped packets to the interface display.
-Cb Show an extended interface status, giving octets in addition to packets.
-Co Show an abbreviated interface status, giving octets in place of packets. This is useful when enquiring virtual interfaces (such as Frame-Relay circuits) on a router.
-CI interface Show information only about this interface; used with an interval as described below.
-Cn Show network addresses as numbers (normally snmpnetstat interprets addresses and attempts to display them symbolically). This option may be used with any of the display formats.
-Cv Allow long host or service names to break the columnar output. This option may be used with any of the display formats.
-Cp protocol Show statistics about protocol, which is either a well-known name for a protocol or an alias for it. Some protocol names and aliases are listed in the file /etc/protocols. A null response typically means that there are no interesting numbers to report. The program will complain if protocol is unknown or if there is no statistics routine for it.
-Cs Show per-protocol statistics. If this is duplicated (-Css) statistics entries which are zero will be suppressed.
-Cr Show the routing tables.
-CR repeaters For GETBULK requests, repeaters specifies the max-repeaters value to use.
When snmpnetstat is invoked with an interval argument, it displays a running count of statistics related to network interfaces. interval is the number of seconds between reporting of statistics.
The Active Sockets Display (default)
The default display, for active sockets, shows the local and remote addresses, protocol, and the internal state of the protocol. 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 databases /etc/hosts and /etc/networks, respectively. If a symbolic name for an address is unknown, or if the -Cn option is specified, the address is printed numerically, according to the address family. For more information regarding the Internet ``dot format,'' refer to inet(3N). Unspecified, or ``wildcard'', addresses and ports appear as ``*''.
The Interface Display
The interface display provides a table of cumulative statistics regarding packets transferred, errors, and col- lisions. The network addresses of the interface and the maximum transmission unit (``mtu'') are also displayed.
The Routing Table 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 pack- ets. The flags field shows the state of the route (``U'' if ``up''), whether the route is to a gateway (``G''), whether the route was created dynamically by a redirect (``D''), and whether the route has been modified by a redirect (``M''). Direct routes are created for each interface attached to the local host; the gateway field for such entries shows the address of the outgoing inter- face. The interface entry indicates the network interface utilized for the route.
The Interface Display with an Interval
When snmpnetstat is invoked with an interval argument, it displays a running count of statistics related to network interfaces. This display consists of a column for the primary interface and a column summarizing information for all interfaces. The primary interface may be replaced with another interface with the -CI option. 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.
The Active Sockets Display for a Single Protocol
% snmpnetstat -v 2c -c public -Ca testhost
Active Internet (tcp) Connections (including servers) Proto Local Address Foreign Address (state) tcp *.echo *.* LISTEN tcp *.discard *.* LISTEN tcp *.daytime *.* LISTEN tcp *.chargen *.* LISTEN tcp *.ftp *.* LISTEN tcp *.telnet *.* LISTEN tcp *.smtp *.* LISTEN ... Active Internet (udp) Connections Proto Local Address udp *.echo udp *.discard udp *.daytime udp *.chargen udp *.time ...
% snmpnetstat -v 2c -c public -Ci testhost
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Queue eri0 1500 10.6.9/24 testhost 170548881 245601 687976 0 0 lo0 8232 127 localhost 7530982 0 7530982 0 0
Example of using snmpnetstat to show statistics about a specific protocol:
% snmpnetstat -v 2c -c public -Cp tcp testhost Active Internet (tcp) Connections Proto Local Address Foreign Address (state) tcp *.echo *.* LISTEN tcp *.discard *.* LISTEN tcp *.daytime *.* LISTEN tcp *.chargen *.* LISTEN tcp *.ftp *.* LISTEN tcp *.telnet *.* LISTEN tcp *.smtp *.* LISTEN ...