Network traffic monitoring tool iftop

iftop Network card traffic monitoring command

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All the result network cards go out , Or come in , adopt iftop Can monitor , This is real-time .

iftop Is a free network card real-time traffic monitoring tool , Be similar to Linux below top command .iftop It can monitor the real-time traffic of the specified network card 、 Port connection information 、 Reverse DNS IP etc. , It can also accurately display the local network traffic and the traffic set of each host in the network communicating with the local computer , It is very suitable for monitoring the network traffic of proxy server or router . perform “iftop -P -i em1” command , Get... As shown in the figure below iftop A typical output interface of .（ Generally, I will filter , For example, display the traffic of a network card , Is to specify a specific network card , In this way, you can know the specific traffic of a network card , If you do the binding of dual network cards , So it's using bond0）

 - P It can display the relationship between host and port , This has a lot to do with checking network performance -n In order to ip To display .

 iftop Network card traffic monitoring command iftop The output of can be divided into three parts as a whole ：

The first part . yes iftop The top line in the output , This line information is the flow scale , Used to display network card bandwidth traffic .

The second part . yes iftop The largest part of the output , This part is divided into left 、 in 、 Three columns on the right , What are recorded in the left and middle columns IP Or the host is connecting to the local network .（ The left side shows the ip, Then the random port communicates with a host , It's the middle column .）

=> Send data on behalf of , conversely <= Is to accept data . Through these two columns, we can clearly see , This machine and the corresponding host , What is the status of sending and receiving data .

For example, a host frantically sends packets to another host , We don't know which host it is going to send , adopt iftop You can clearly see what data they send and receive through this network card and a designated host .

The rightmost one shows the outside ip Connect to native ,2s Inside ,10s Inside ,40s An average flow value in , Display the flow values in different time periods .

The third part is located in iftop The bottom of the output , It can be divided into three lines , among ,“TX” Means send data ,“RX” Indicates receiving data ,“TOTAL” It means sending and receiving all traffic .

cum： From run iftop Send a traffic that accepts total data to the front .

peak： Peak flow

rate： In the past two seconds ,10s,40s, Average flow value .

iftop Application scenarios

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Server bandwidth is severely exhausted , But the business volume is not large , No available bandwidth makes the business system unable to operate normally , It's urgent to know what's going on .（ With which machine on the Internet , Crazy contract awarding ）

Online business systems often consume a lot of bandwidth , But the source of bandwidth consumption cannot be found . Want to know the bandwidth occupation of online business system