分类： LINUX
2008-03-03 09:58:02
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 (1) for a full list of the possible formats for AGENT.
OPTIONS
The options have the following meaning:common options Please see (1) for a list of possible values for common options as well as their descriptions.
-a With the default display, show the state of all sockets; normally sockets used by server processes are not shown.
# 注释 ：-a 表示默认输出，显示所有 socket 的状态
# 注意，在 windows 版本的 snmpnetstat 中，改为 -Ca
-i 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.
# 注释 ：-i 显示网络接口的状态。
# 注意，在 windows 版本的 snmpnetstat 中，改为 -Ci
-o 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.
-I interface Show information only about this interface; used with an interval as described below.
# 注释 ：-I
# 在 windows 下则为 -CI
-n 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.
# 注释 ：-n 显示以 ip 方式显示地址，而不是主机名
-P protocol Show statistics about protocol, which is eithe
r 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.
# 注释 ：-p
# 具体查看 /etc/protocols 文件
# 注释 ：如果输出为空，则表示没有有用的信息可供输出
# 如果协议名称不正确，snmpnetstat 会报错
-s Show per-protocol statistics. When used with the -r option, show routing statistics instead.
# 注释 ：-s 选项显示每个协议的统计信息。
# 包括 ip、icmp、tcp、udp
# windwos 下为 -Cs
-r Show the routing tables. When -s is also present, show per-protocol routing statistics instead of the routing tables.
# 注释 ：-r 显示路由信息
# 当存在 -s 时，显示每个路由的统计信息
# windows 下为 -Cr
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.
# 注释 ：当指定 interval 时，snmpnetstat 定时输出接口的统计信息
# 单位是秒，windows 版下是 -Cw
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 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 numerically, according to the address family. For more information regarding the Internet ``dot format,'' refer to (3N). Unspecified, or ``wildcard'', addresses and ports appear as ``*''.
# 注释 ：默认的 -a （-Ca）显示活跃的 sockets ，本地和远程地址，协议，协议的内部状态
# 地址的格式是 “host.port" 或者 "network.port" 。
# 默认情况下会显示主机名，除非使用 -n 或者主机名不可知
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.
# 注释 ：-i 或者 -Ci 显示接口的累计统计信息，包括 MTU、IP/mask 、接收/发送的 packet、错误的packet、冲突的 packet
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.
# 注释 ：-r 或者 -Cr 显示路由表。
# Flags 字段可以是 U（UP）、D（Dynamatic）、G（Gateway）、M（Redirect）、H（Host 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 -I 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.
# 注释 ：当指定 interval 时，snmpnetstat 会持续显示所有接口的统计信息，并以 interval 作为间隔
#
第一行输出是自从系统上次重启后的数据，此后的每一行都是上一行的差值
The Active Sockets Display for a Single Protocol
When a protocol is specified with the -P option, the information displayed is similar to that in the default display for active sockets, except the display is limited to the given protocol.
# 注释 ：当使用 -P 时，snmpnetstat 只显示指定协议的统计信息，而不是 -s 的全部协议的统计信息
% snmpnetstat -v 2c -c public -a 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 -i 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 -P 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
