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netstat command is a very useful tool to monitor a TCP / IP network, and displaying the status of the routing table, the actual network connections, and each network interface device information.
Syntax Options
netstat [options]
-a or --all: all wiring in the Socket;
-A <network type> or - <network type>: connection type are listed in the network for an address;
-c or --continuous: maintains a list of network status;
Or -C --cache: displaying information routers cache configuration;
-e or --extend: Displays network other relevant information;
-F or --fib: displaying the FIB;
-g or --groups: display multiple broadcast function group members list;
-h or --help: online help;
-i or --interfaces: displaying information form the network interface;
or -l --listening: displaying the Socket server monitoring;
-M or --masquerade: cloaked network connection;
-n or --numeric: ip address directly, without passing through the domain name server;
Or -N --netlink or --symbolic: display symbols hardware peripherals connected to the network name;
-o or --timers: timer display;
-p or --programs: display program identifier and the program name being used Socket;
-r or --route: display Routing Table;
-s or --statistice: display networking information tables;
-t or --tcp: display the connection status of the TCP transport protocol;
-u or --udp: display the connection status of the UDP transport protocol;
-v or --verbose: display instruction execution;
-V or --version: show the version information;
-w or --raw: connection status display RAW transmission protocol;
-x or --unix: effect of this parameter is specified and "-A unix" the same parameters;
--ip or --inet: effect of this parameter is specified and "-A inet" the same parameters.
Netstat command for displaying various information networks, such as network connection, routing tables, interface (Interface Statistics), masquerade connections, multicast membership (Multicast Memberships) etc.
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 2 210.34.6.89:telnet 210.34.6.96:2873 ESTABLISHED
tcp 296 0 210.34.6.89:1165 210.34.6.84:netbios-ssn ESTABLISHED
tcp 0 0 localhost.localdom:9001 localhost.localdom:1162 ESTABLISHED
tcp 0 0 localhost.localdom:1162 localhost.localdom:9001 ESTABLISHED
tcp 0 80 210.34.6.89:1161 210.34.6.10:netbios-ssn CLOSE
Active UNIX domain sockets (w/o servers)
Proto RefCnt Flags Type State I-Node Path
unix 1 [ ] STREAM CONNECTED 16178 @000000dd
unix 1 [ ] STREAM CONNECTED 16176 @000000dc
unix 9 [ ] DGRAM 5292 /dev/log
unix 1 [ ] STREAM CONNECTED 16182 @000000df
Overall, netstat output can be divided into two parts:
A is Active Internet connections, called an active TCP connection, where "Recv-Q" and "Send-Q" refers to% 0A the transmit queue and receive queue. These numbers are generally should be zero. If not, it means the package is in the queue accumulation. This situation can only be seen in very few cases.
Another is the Active UNIX domain sockets, called active Unix domain sockets (socket and the same network, but only for the native communication, the performance can be doubled).
Proto display protocol used by the connection, RefCnt represents the number of connections to the process of the present socket, Types display socket type, State displays the current state of the socket, Path represents a path name to connect to other process uses socket.
If your computer sometimes received data packets result in an error or malfunction, you should not be surprised, TCP / IP can allow these types of errors, and automatically retransmit packets. But the IP datagram if the number of error conditions received a total accounted for a substantial percentage, or its number is increasing rapidly, then you should use the netstat check out why there is such a situation.
1. Format:
netstat [-acCeFghilMnNoprstuvVwx] [- A <network type>] [- ip]
2. Function:
netstat for displaying IP, TCP UDP and ICMP statistics related generally to network connection of each port of the unit test.
3. Command parameters:
-a or -all displays all connections in the Socket.
-A <network type> or - <network type> list the type of network connection for an address.